DESC:FIELD OF INVENTION
[0001] The present disclosure relates to the field of determining the hair damage. In particular, the present disclosure provides a method to evaluate hair and scalp care products based on evaluation of hair damage, especially by determining change in hair properties on weathering and provide hair damage protection metric to evaluate hair care products.

BACKGROUND OF THE INVENTION
[0002] Hair is a unique bio-composite given the complexity in terms of structure, morphology, composition and physical properties. Besides protecting head from external factors, hair plays an important role in one’s beauty and appearance and social acceptability. Though the hair emerges from the scalp, in case of subjects with longer hair, it actually spends nearly 12-18 months exposed to external environment. Over time, it undergoes various damages due to many extraneous factors such as washing, shampooing, combing, coloring, environmental exposure such as pollution, humidity etc., and physical treatments.
[0003] Hair damage is a universal problem faced by people of all age and race. Many factors cause hair damage and evaluating hair damage to understand the cause, or take corrective measures at personal level is a continuous pursuit. Desire for healthy and beautiful looking hair drives people to try and adopt various grooming products and do styling. Many of the hair care products like shampoos, conditioners, gels, and hair colours contain very harsh chemicals damaging hair. Hair straightening or curling done using various chemical agents and straightening or curling irons, is carried out on a huge scale, such chemical or physical treatments result in changes to hair structures and chemistry causing hair damage. Though the haircare or hair grooming products and equipment provide the desired look superficially for a short duration but on a longer run cause damage to hair shaft making it prone to fracture or breakage and thus lead to hair loss. In addition to exposing hair to chemical and physical treatments, medication, exposure to sun and pollution also cause undesirable changes to the hair characteristics. These factors compromise the health of the hair to a varying degree which manifests itself as weak, dull, rigid, rough and unmanageable hair.
[0004] Assessing hair damage is a challenge at an individual level as it is difficult to differentiate between the routine hair fall and hair damage and ultimately hair loss. Hair Fibre has varying diameter across the length of strand which can be attributed to hair weathering over the course of time since its emergence from scalp. The various experimentation studies with natural, irregular fibres have established that fracture is the result of crack propagation from a flaw or from regions with high localized stress.
[0005] Determining acquired hair shaft fragility and breakage are a large problem and of paramount importance to the dermatologist for recommending and for consumers to choose appropriate products. Dermatologists recommend tests like checking level of hormones like DHEA, testosterone, androstenedione, prolactin, follicular stimulating hormone, and luteinizing hormone; possible deficiency of serum iron, serum ferritin, and total iron binding capacity (TIBC); thyroid levels (T3, T4, TSH); a screening test for syphilis like VDRL; complete blood count (CBC); etc. Other methods include scalp biopsy, wherein a small section of scalp is removed and examined under a microscope to help determine the cause of hair loss. Such methods are however clinical in nature and need to be specifically prescribed by the dermatologist or cosmetologist considering individual’s problem of hair loss and other conditions and are always not necessary. In many situations, dermatologists or cosmetologists use techniques like spectroscopic imaging and fluorescence spectrophotometry as tools to assess the biochemical state of the hair fiber as a result of hair shape modification regimens. Some of the approaches propose monitoring structural integrity of the hair fiber with the help of dynamic scanning calorimetry and traditional mechanical testing of the tensile properties of hair.
[0006] However, very complex clinical and biochemical testing methods used by dermatologists and cosmetologists are not practical or required to be used at an enterprise level for companies manufacturing hair and scalp care products. Those developing hair and scalp care products require to determine or predict the effect of hair care or grooming products, individual components, or equipment which can be suitable for a larger number of consumers and not necessarily dependent on specific individual patient’s hormone or biochemical levels. Companies engaged in carrying out research and development of hair care products also like to evaluate the good or bad impact of the product on hair, in particular if the hair shaft is getting weaker, brittle, fragile, and prone to fracture or breakage, or is getting extracted from the scalp and thereby causing hair damage and hair loss. Similarly, consumers are interested in knowing the hair protection ability of the various hair or scalp care products or equipment. Hair breakage is considered a commonly used parameter to evaluate or describe the ability of the product to provide protection to hair. Indicator of Hair protection accorded by hair care product or regime is needed to help equip users with better personalized choices.
[0007] There are some studies reported which quantifies the broken hair by breakage or hair bulb extraction of a single hair. However, these approaches merely provide a comparative estimation of different treatments or mode of application but do not suggest manner of evaluation to assess consumer hair breakage.
[0008] The existing methods and proposed approaches are not satisfactory due to perception of hair breakage and actual consumer grooming behavior. Methods like fatigue experiments on single fiber does not take into account the high degree of forces experienced during detangling knots of multiple hair, tensile extension method for strength measurement suffers from shortcoming of hair getting extracted and plucked out from scalp before reaching the break force, automated grooming method cannot be correlated to manual continuous hair combing, instead it suffers from the drawback of excessive number of combing cycles required which leads to unreasonable time frame to normal grooming habits of consumer, flexabrasion method adds abrasion to extension force and still fails to provide direct correlation with consumer-perceived hair breakage.
[0009] Hence, there does exists an unmet need to provide a method and techniques to evaluate hair and scalp care products based on evaluation of hair damage, especially by determining change in hair properties on weathering or propensity to fracture of the hair shaft and provide hair damage protection metric to evaluate hair care products that can be reliable on a large scale such as at enterprise level while developing the hair care or hair grooming product, components or tools and assessment of such products or tools by consumers enable them to choose product capable of protecting hair.

OBJECTS OF THE INVENTION
[00010] An object of the present disclosure is to provide a method to evaluate hair and scalp care products based on evaluation of hair damage, especially by determining change in hair properties on weathering or propensity to fracture of the hair shaft and provide hair damage protection metric.
[00011] One more object of the present disclosure is to provide a method or techniques for evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters.
[00012] One object of the present disclosure is to provide a method or techniques for evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters, which can be implemented at a large scale for example at an enterprise level while developing the hair care or hair grooming product or assessing already existing product.
[00013] These and other objects of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY
[00014] In an aspect the present disclosure provides a method to evaluate hair and scalp care products based on evaluation of hair damage, especially by determining change in hair properties on weathering the propensity to fracture of the hair shaft and provide hair damage protection metric.
[00015] In one aspect the present disclosure provides a method for evaluating hair damage by measuring propensity of hair shaft to fracture by determining the weakest link of hair fiber.
[00016] In one aspect the present disclosure provides a method to evaluate hair and scalp care products by determining change in hair properties on weathering the propensity to fracture of the hair shaft, in which method comprises:
a) sourcing hairs and keeping under controlled environmental conditions of temperature and humidity;
b) washing hairs with a hair damage inducing agent and rinsing with water;
c) subjecting hairs to one or more treatment with a hair or scalp care product;
d) incubating the treated hairs under defined condition of temperature and humidity for the predetermined period and rinsing the hairs;
e) determining a weakest link progression in terms of a variability in mean diameter of hair strand due to effect of the hair or scalp care product treatment comprising:
i) measuring variations in hair strand mean diameter across length of hair strand including root and tip regions before and after carrying out steps (b) to (d);
ii) determining breakage point location by subjecting the hair strand to extension before and after carrying out steps (b) to (d); and
f) evaluating hair and scalp care products by quantifying the control of the hair damage progression.
[00017] In one aspect the determination of a weakest link progression in terms of a variability in mean diameter of hair strand due to effect of the hair or scalp care product treatment further comprises a step of analyzing hair surface topography, average count of gaps and micro-cavities in a selected section of hair sample.
[00018] In an aspect the present disclosure provides an indicator metric that can enable a consumer to evaluate and choose product capable of hair protection.
[00019] In an aspect the present disclosure provides an indicator metric a Hair Protection Factor (HPF) based on the damage control power of a product determined in accordance with the method to evaluate hair and scalp care products.
[00020] Another aspect of the present disclosure is to provide a method for evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters.
[00021] In an aspect the present disclosure provides a method or techniques for evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters, which can be implemented at a large scale for example at an enterprise level while developing the hair care or hair grooming product or assessing already existing product.
[00022] In one aspect the present disclosure provides a method for evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters selected from weakest link of hair fiber, average count of gaps and micro-cavities in a selected section of hair sample, curvature of hair shaft, cross-section area of hair shaft, elastic modulus of hair shaft, work done, normalized work done, toughness of a hair shaft, break stress, smoothness force, initial detangling force, later detangling force, frizz, hair volume, hair density, and age of the subject.
[00023] In one aspect the present disclosure provides a method for evaluating hair damage by measuring propensity of hair shaft to fracture by determining one or multiple parameters selected from the weakest link of hair fiber, smoothness force, initial detangling force, later detangling force, and hair density.
[00024] In one aspect the present disclosure provides a method for evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters, wherein such method can be carried out in a controlled environment by implementing technological tools like micrometer, camera, a microscope camera, a camera coupled to an imaging sensor for imaging and image analysis of physical appearance of hair shaft, a comb coupled with sensor for detecting and measuring force encountered by hair shaft, hair tensile tester, laser scanning microscope; and carrying out procedures manually and/or in automated manner for a single or multiple parameter testing(s).
[00025] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

DETAILED DESCRIPTION OF THE INVENTION
[00026] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.
[00027] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[00028] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[00029] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[00030] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about”. Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The term “about” in certain embodiments represent +10%.
[00031] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[00032] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability.
[00033] All methods described herein can be performed in suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[00034] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[00035] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[00036] Various terms are used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[00037] The expression “hairs”, “hair fibers”, “hair strands” in plural form are used interchangeably and have the same meaning.
[00038] The expression “hair fiber”, “hair strand”, and “hair shaft” in singular or plural form are used interchangeably and have the same meaning.
[00039] The expression “hair and scalp care product” refers to and can include various products such as hair oil, hair crème, hair tonics, hair elixirs, hair lotion, hair shampoo, hair conditioner, anti-dandruff product, hair styling gels, hair colour, hair dye, hair serum, or like products as well hair styling tools and equipment like hair iron, hair curler, hair spa equipment, or any other hair grooming tools and accessories. The expression “hair and scalp care product” also includes various ingredients, constituents, components, agents, excipients that can be used in the hair and scalp care products and the effect of which needs to be evaluated for their ability to protect hair or cause damage.
[00040] The expression “smoothness force” refers to force required to compress hair fibres into the spaces between the teeth of comb and separation of the tress as the teeth of the comb move through the hair.
[00041] The present disclosure relates to a method or techniques for evaluating hair damage, by measuring propensity of hair shaft to fracture by one or multiple parameters.
[00042] In an embodiment the present disclosure provides a method to evaluate hair and scalp care products based on evaluation of hair damage, especially by determining change in hair properties on weathering the propensity to fracture of the hair shaft and provide hair damage protection metric.
[00043] The inventors of the present invention found that the mean diameter of human scalp hair is prone to a lot of variation; it was observed hair diameters in Indian population ranges from 30 to 140 µm. Generally, the hairs are classified as thick (>66 µm), medium (51-65 µm) and fine (<50 µm). The variation seen in hair mean diameter across a strand has been classified as a) constant, b) slight smooth variation, c) wide smooth variation and d) abrupt variation. However, neither the inter-strand mean diameter variation amongst scalp hairs of an individual nor the intra-strand mean diameter variation across length so far have been found to have a little correlation with a given individual. Heretofore, weakest link based on dimensional irregularities has not been known to assess the impact of ‘weakest link’ progression with hair treatment products as well as hair lifestyle practices.
[00044] In one embodiment there is provided a measure for hair surface irregularity to determine the state of weakest link in hair. Hair damage begins at the surface penetrating to interior causing flaws responsible for hair breakage due to repeated bending, and extension.
[00045] In one embodiment, evaluation of the weakest link of the hair strand comprises of: correlating dimensional parameters selected from average cross-sectional area and mean diameter of a hair strand with a point of breakage; determining the ‘weakest link’ progression in terms of intra-strand irregularities; quantifying the weakest link progression due to factors selected from but not limiting to differentiating root and tip region of hair strands and chemical treatments inducing hair damage; and quantify the weakest link progression for factors selected from but not limiting to damage vectors, treatment options and usage habits of subjects.
[00046] In one embodiment, the measure for evaluating the weakest link of the hair strand is provided in the form of a measure for determining the influence of the hair care product and treatment protocols on the weakest link progression and thus provides a manner of evaluating the hair and scalp care product.
[00047] In one embodiment the present disclosure provides a method to evaluate hair and scalp care products by determining change in hair properties on weathering the propensity to fracture of the hair shaft, in which method comprises:
a) sourcing hairs and keeping under controlled environmental conditions of temperature and humidity;
b) washing hairs with a hair damage inducing agent and rinsing with water;
c) subjecting hairs to one or more treatment with a hair or scalp care product;
d) incubating the treated hairs under defined condition of temperature and humidity for the predetermined period and rinsing the hairs;
e) determining a weakest link progression in terms of a variability in mean diameter of hair strand due to effect of the hair or scalp care product treatment comprising:
i) measuring variations in hair strand mean diameter across length of hair strand including root and tip regions before and after carrying out steps (b) to (d);
ii) determining breakage point location by subjecting the hair strand to extension before and after carrying out steps (b) to (d); and
f) evaluating hair and scalp care products by quantifying the control of the hair damage progression.
[00048] In one embodiment the determination of a weakest link progression in terms of a variability in mean diameter of hair strand due to effect of the hair or scalp care product treatment further comprises a step of analyzing hair surface topography, average count of gaps and micro-cavities in a selected section of hair sample.
[00049] In an embodiment, the sourcing hairs can be carried out of a subject of specific age group, preferably female subjects. Hair tresses of desired length can be sourced preferably from female subjects for example hair strands having length ranging from about 5 cm to about 50 cm, preferably having length of more than about 10 cm. Hair strands can be sourced from a group of subjects who have not undergone chemical or thermal treatment(s) to provide a hair sample of virgin category. Such subjects can be those who have not undergone any chemical treatment like bleaching, perming, colouring as well as not using any styling products like hair iron or other hair styling equipment, but using regular shampoo for cleansing. The other group can be those using a specific hair or scalp care product.
[00050] In one embodiment the sourcing of hair strands includes procuring hairs from saloon or beauty clinics or parlors or collecting hair tresses from a subject by cutting the strands from different sections of scalp and as close to the scalp as possible for example typically leaving distance of 1-2 cm from scalp. The collected hair strands can be marked to identify the root and tip section. The specific number of hair strands can be collected from each group for example ranging from about 500 hair strands to about 5000 hair strands, preferably from about 1000 hair strands to about 2000 hair strands. The collected hair strands are divided into multiple hair samples comprising hair swatches having defined weight, for example each hair swatch may weigh 1 gm to 25 gm, preferably, 2 gm to 10 gm.
[00051] In an alternate embodiment sourcing of hairs from a subject can be carried out by combing hair of the subject for fixed period of time for example, about 60 seconds to about 300 seconds and then collecting the fallen hair. In another alternate embodiment, the sourcing of hair can be carried out by running fingers through hair of the subject from scalp to end on both the right and the left sides of head, for fixed time, for example for about 60 seconds to about 150 seconds each side followed by combing hair for a fixed period of time for example for about 60 seconds to about 120 seconds and collecting the fallen hair.
[00052] In an embodiment prior to sourcing of the hairs the subject may be subjected to normalization by allowing the subject to a standardized condition of an ambient temperature for example about 25 degree centigrade, and a humidity of about 60% RH, for a predetermined period.
[00053] In an embodiment, the sourced hair strands individually or in the form of hair swatches can be stored under controlled environmental conditions for example of the temperature ranging from about 10 oC to 40 oC (+/- 5oC) and the humidity ranging from about 40% to about 75% (+/- 5%) relative humidity (RH) for a predetermined period for example for about 30 minutes to about 24 hours, preferably from about 2 hours to about 8 hours prior to subject the sourced hair fibers to the method of evaluation of the present disclosure.
[00054] In an embodiment for benchmarking the general grooming damage, hair wash cycles comprising application of the hair damage inducing agent, hand wringing, rinsing, drying and combing exposure can be used as the damage vector.
[00055] In an embodiment hair damage inducing agent can be a surfactant for example sodium lauryl sulfate (SLS) or a product like shampoo, or any other agent capable of causing damage to hair fibers.
[00056] In an embodiment the step of washing hairs with a hair damage inducing agent comprises:
- applying desired quantity of a damage inducing agent;
- rubbing hairs in regulated manner by subjecting hairs with defined number of strokes in each side of the swatch in a back and forth motion;
- rinsing hairs with water by rubbing hairs multiple times on each side in back and forth motions for a defined period with water; and
- drying hair swatches under ambient temperature and humidity.
[00057] In an embodiment the subjecting of the hairs to treatment with hair or scalp care product comprises pouring the hair treatment product in a defined concentration over hairs, covering hairs uniformly with the hair treatment product for example by rubbing hairs with the hair treatment product multiple times on each side in back and forth motion.
[00058] In an embodiment incubating of the treated hairs under defined condition of temperature and humidity for the predetermined period can be carried out in a chamber with controlled conditions of temperature and humidity for example, the temperature may range from about 10 oC to 40 oC (+/- 5oC) and the humidity may range from 40% to 75% (+/- 5%) of relative humidity (RH), for a predetermined period for example ranging from about 0.5 minute to about 24 hours or more depending upon the type of the hair or scalp care product. For example, the duration of incubation for hair oil type of product can range from about 2 hours to 24 hours, the duration of crème oil type of product can be about 10 minutes to about 60 minutes, the duration of shampoo or conditioner can be for about 0.1 minutes to about 10 minutes.
[00059] In an embodiment the hair strand collected from the subject before and after subjecting the hair strands to the damage inducing agent and treatment with the hair or scalp care product is measured for the mean diameter across the length from the root. Hair morphology being elliptical the cross-section has been approximated by a mean circular diameter for analysis. The variability in the mean diameter of the hair strand serves as a measure for defining the hair damage caused leading to the weakest link progression.
[00060] In an embodiment, variations in diameter at different points across the length of the hair strand is determined to assess the hair strength and propensity to breakage of hair strand which can be due to the effect of one or more causative factors. Weakest link in hair as per the inventors of the present invention is found to be embodied by presence of internal defects, which is preceded by surface irregularities. For evaluating the weakest link in hair fiber, surface irregularities and internal defects are determined across the length of hair strand from root to the tip. Based on the extensive experiments carried out by the inventors of the present invention, the irregularity in hair strands in terms of the Root Mean Square Variability is found to be proportional to the weakest link in hair strand. Accordingly, an increase in Root Mean Square Variability corresponds to the hair strand breakage.
[00061] In an embodiment, for measuring the diameter the hair strands are crimped. Diameter of hair strand is measured before and after treatment using a suitable equipment, for example a Laser Scan Micrometer by taking number of scans across the length at uniform spacing. Since, the human hair strand is largely elliptical in cross-section the mean diameter and average cross-sectional area are measured. The readings are computed for specific sections across the crimped length. Data is tabulated and minimum, maximum and average of mean diameter, cross-sectional area, and minimum and maximum change in mean diameter sections of the hair strand is computed. Root Mean Square Deviation is quantified for every strand from the mean diameter of different sections and the average mean diameter.
[00062] In an embodiment quantification of the ‘weakest link progression’ can be determined in terms of Root Mean Square Variability (Rq)

Where, = Average of Mean Diameter of Hair Strand
= Mean diameter of Section ‘k’ of the Hair Strand
N = number of diameter scans across a single hair strand
[00063] In certain embodiments, determination of one or more of weakest link progression as a function of time; weakest link progression by in-vivo usage study; and weakest link progression for simulated ex-vivo scenarios can be carried out.
[00064] In one embodiment, the method of the present disclosure includes assessing the impact of a hair care product or a hair treatment format by determining of the weakest link progression due to the effect of the specific hair care product or the hair treatment format.
[00065] In an embodiment the weakest link progression in different groups of subjects including those not using any hair care product is determined by collecting hair samples and evaluating average cross-section and mean diameter of various location of hair strand and determining location of breakage point on hair extension. Based on such evaluation, breakage point and hair mean diameter is correlated as function of length. Data obtained from such evaluation is extrapolated to evaluate the quality of hair samples in another group of subjects using the hair care product or various hair treatments.
[00066] In an embodiment the hair care product is evaluated by quantifying the control of the hair damage progression in terms of the Hair Protection Factor (HPF) established in accordance with the present invention.
[00067] The Hair Protection Factor (HPF) in accordance with the present disclosure is a measure of the weakest link of the hair strand determined based on the variability of hair mean diameter Rq. The HGF can be determined as:

[00068] In accordance with the present disclosure, a 15 point scale is used to calibrate the HGF with the baseline including:
HPF 1 ? Untreated Hair undergone 20 cycles of SLES wash
HPF 15 ? Virgin Hair (Untreated Hair)
[00069] The present invention thus provides a novel metric to quantify damage control power of hair and scalp care products in terms of Hair Protection Factor (HPF). Such novel metric based on Root Mean Square Deviation can also help compare different hair and scalp care products or hair care treatments to control hair damage.
[00070] In one embodiment the present disclosure the method to evaluate hair and scalp care products optionally comprises determining change in hair properties on weathering the propensity to fracture of the hair shaft by additional parameter(s) selected from curvature of hair shaft, cross-section area of hair shaft, elastic modulus of hair shaft, work done, normalized work done, toughness of a hair shaft, break stress, frizz, hair volume, smoothness force, initial detangling force, later detangling force, hair density, and age of the subject.
[00071] In one embodiment the method to evaluate hair and scalp care products in accordance with the present disclosure by evaluating hair damage as a measure of propensity of hair shaft to fracture by one or multiple parameters can be carried out in a controlled environment by implementing technological tools like micrometer, camera, a microscope camera, a camera coupled to an imaging sensor for imaging and image analysis of physical appearance of hair shaft, a comb coupled to a sensor for detecting and measuring force encountered by hair shaft, hair tensile tester, laser scanning microscope; and carrying out procedures manually and/or in automated manner for a single or multiple parameter testing(s).
[00072] In one embodiment the present disclosure provides the method to evaluate hair and scalp care products method by evaluating hair damage by measuring propensity of hair shaft to fracture by one or multiple parameters optionally comprising of:
i) carrying out an evaluation of a single hair shaft by measuring:
one or more parameters selected from a weakest link of hair fiber, curvature of hair shaft, a cross-section area of hair shaft, an elastic modulus, toughness of single hair shaft, work done at 25%, and breaking stress of hair shaft; or
ii) carrying out an evaluation of hair mass by measuring:
one or more parameters selected from a frizz, a hair volume, a smoothness force, an initial detangling force, and a later detangling force; or
iii) carrying out evaluation based on:
one or more of a hair density, and age of the subject; or
combination of (i), (ii) or (iii).
[00073] In one aspect the present disclosure provides a method for evaluating hair damage by measuring propensity of hair shaft to fracture by determining one or multiple parameters selected from the weakest link of hair strand, smoothness force, initial detangling force, later detangling force, and hair density.
[00074] In an embodiment, evaluation of the frizz of hair is carried out with the help of a photographic image(s) of the posterior side of the head of the subject showing full breadth and length of hair. The Frizz is determined based on the area outermost to the contour of the complete length and breadth of hair, and end portion of single hair strands protruding out in such outermost defined area. The number of single hair strands in such defined area reflects the fly away frizz. The photographic image of the posterior side of the subject’s head with full length and breadth is captured against a bright and light coloured or white background and the subject wearing the same light coloured or white cloths, coat or apron and hair of the subject facing the camera. The scale and threshold of the photographic image is adjusted such that the number of hair strands protruding out in the defined outermost area can be determined.
[00075] In one embodiment, such frizz evaluation is carried out with the help of a system including a non-transitory storage device coupled to one or more image receiving component(s), one or more image processing component(s), one or more image based feature extraction component(s), in which one of the feature extraction component being specific to the feature with respect to the protruding out single hair strands, and computing component operable to receive one or more images captured by the camera, receive and execute commands for defining the area outermost to the contour of hair comprising single hair stands protruding out in said defined area, executing the command to adjust the scale and threshold of the photographic image, processing the defined area of the image and determining the frizz by for extracting and detecting the feature in respect of the protruding single hair strands, and computing the number of protruding single hair strands in the defined area.
[00076] In an embodiment, evaluation of the hair volume is carried out with the help of multiple photographic images comprising left side image, right side image and the posterior side of the head of the subject showing full breadth and length of hair. The hair volume is estimated taking into account the volume of hair in each of the images. The photographic images of the left side, right side, and posterior side of the subject’s head with full length and breadth are captured against a bright and light coloured or white background and the subject wearing the same light coloured or white cloths, coat or apron and each side of hair of the subject facing the camera.
[00077] In one embodiment, estimation of the hair volume is carried out with the help of a system including a non-transitory storage device coupled to an image receiving component, one or more of an image processing component(s) capable of processing multiple images and converting them to three dimensional image, and computing component operable to receive one or more images captured by the camera, receive and execute commands for defining the area of hair in each image, executing the command to adjust the scale and threshold and converting the multiple photographic images including the left side, right side and posterior side images of hair into three dimensional image and determining the volume of hair mass.
[00078] In one embodiment, the smoothness force, the initial detangling force, and the later detangling force is determined with the help of a comb coupled to a sensor for detecting and measuring force encountered by hair shaft.
[00079] In one embodiment, the comb for determining the smoothness force, the initial detangling force, and the later detangling force is coupled to a sensor for detecting and measuring force encountered by hair shaft, as well as coupled to a non-transitory storage device, and one or more processors coupled to the non-transitory storage device and a computing device. Such comb when operated while combing is capable of detecting a force encountered by hair shaft, capturing and analyzing the force encountered by hair, receiving and retrieving information specific to a subject under the study by processing the said encountered force and reporting value corresponding to the force encountered. Such comb is further provided with an accessory like a clasp or a clip for securing the specific quantity of hair to uniformly determine the force encountered.
[00080] In one embodiment, to determine the smoothness force, after detangling larger knots and securing hair with a clip, the comb coupled to a sensor is passed through hair until half the length of hair for multiple times, at least for three time, information about the subject is fed in the device, the force encountered by the hair shaft is measured with the help of computation device and the smoothness force is inferred by plotting the graph.
[00081] In one embodiment, to determine the detangling force, the comb coupled to a sensor is passed through hair secured with clip from half the length of hair until the end of the hair shaft for multiple times, at least for three time, the force encountered by the hair shaft is measured with the help of computation device and the detangling force is inferred by plotting the graph.
[00082] In one embodiment, the curvature of a single hair shaft is measured by selecting the long hair strands collected post combing or running fingers followed by combing, cutting the long hair strand into fragments of uniform defined length from the hair root tip, placing the cut hair strand on the center of the STAM curvature chart and discovering the corresponding curvature line on the STAM curvature chart and the type of the curvature is determined. The curvature diameter of the hair stand is determined with the help of the curvature diameter chart.
[00083] In one embodiment, the cross-sectional area of the hair strands is measured using a laser scanning micrometer. Hair strands collected post combing or running fingers followed by combing, are selected based on the length suitable to be fixed in a laser scan micrometer, the cross section is measured at a room temperature and a suitable relative humidity for example at about 65% RH to about 75% RH, and, by taking specific number of slices, at offset distance of about 5 mm to about 10 mm, at 100% motor power and taking a scan or number of scans to be able to measure the cross section of a hair shaft.
[00084] In one embodiment, tensile properties of single hair shaft including elastic modulus, toughness of a single hair strand, work done at 25%, and breaking stress are determined using a tensile tester. Hair strands collected post combing or running fingers followed by combing, are selected based on the length suitable to be crimped. Hair strand was crimped using the crimping block supplied with the tensile tester instrument by applying gauge force of 1 gmf to 2000 gmf at the speed of 20 mm per minute allowing 100% extension and break threshold of 10. The test data is analyzed using the tensile tester instrument.
[00085] In one embodiment, the hair density is measured using a microscope camera coupled to one or more image processor and computation device, calibrated with a fixed dimension and fixed resolution. For measuring the hair density, the camera is held onto the scalp at desired places, and number of images are captured with the same resolution as that of the microscope camera, analyzing the captured images by cropping the each captured image in the form of a fixed circle and the dimension, counting the number of hair shafts in proximity to the follicle region present in the cropped circular region and determining the hair density per square centimeter.
[00086] In an embodiment, to evaluate hair and scalp care products to determine the effect of a desired product on the hair damage, each of the evaluations including the evaluation of hair mass by measuring one or more parameters selected from a weakest link of hair fiber, frizz, a hair volume, a smoothness force, an initial detangling force, and a later detangling force; as well as evaluation of a single hair shaft by measuring one or more parameters selected from a curvature of hair shaft, a cross-section area of hair shaft, an elastic modulus, toughness of single hair shaft, work done at 25%, and breaking stress of hair shaft and; is carried out before and after applying the product. Such determination of the effect of the product can be carried out either immediately post application, after certain duration of application, periodically at a regular interval.
[00087] The present disclosure provides a method for evaluating hair damage, especially by measuring fracture or propensity to fracture of the hair shaft by minimum number of parameters in simple and reliable manner.
[00088] Overall, the present disclosure provides a simple and reliable method to evaluate hair and scalp care products by evaluating the hair damage in terms of fracture or propensity to fracture of the hair shaft.
[00089] One or more of the evaluations and outcome of the same help assess the effect of various hair care products and tools and thereby help design product to either prevent or recover the damage caused to the hair fiber either by correction and/or management of hair damages.
[00090] The present disclosure satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
[00091] From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein merely for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention and should not be construed so as to limit the scope of the invention or the appended claims in any way.
Example 1
Evaluation of hair care products by determining Hair Protection Factor (HPF) to control the weakest link
[00092] The method comprised of following steps:
A. Sourcing hairs
(a). Sample collection for in-vivo study
[00093] Samples of hairs were collected from female subjects of age ranging from 25 to 35 years and having hair length exceeding 35 cm. The subjects were regular shampoo users without having any history of use of any chemical treatment for example coloring, curling or styling. Two groups of the subjects were created:
i) Non-Oil Users: Subjects not using any hair care product like hair and
ii) Users of Coconut Oil: Subjects using coconut oil once or twice as their hair care regime.
[00094] 20 hair strands were collected from each of the subject by cutting the strands 1-2 cm gap from scalp from different sections of scalp. The hair strands were individually marked to identify the root and tip section. A total of 1200 hair strands per group (20 hair strands x 2 sections x 30 subjects) were analyzed for the in-vivo study.
(b). Sample collection for in-vitro studies
[00095] Samples of 20 cm long tresses of Indian subjects were sourced from a local supplier. The virgin hair samples supplied were obtained from users which did not undergo chemical or thermal treatment(s). Samples procured were divided into number of swatches each weighing 5gm.
[00096] The hair samples collected were stored under controlled environmental conditions of temperature of 25oC (+/- 1oC) and humidity at about 60% relative humidity (RH) (+/- 2%) for a minimum of 3 hours prior to different analysis.
B. Measurement of Hair Strand Mean Diameter Variations’
[00097] Different conditioned hair samples were used for this study. 30 mm long hair strands were crimped. Diameters of hair strands were measured before and after treatment using Laser Scan Micrometer (Model LSM-6200). The instrument so programmed collected 10 scans across the length at uniform spacing. The instrument provided data for Mean diameter and Average Cross-sectional area since the human hair strand is largely elliptical in cross-section. The readings were computed for 10 sections across the crimped length of 30 mm. The data was tabulated in MS Excel® and the observations were computed including minimum, maximum and average of mean diameter as well as cross-sectional area, sections of the hair strand with minimum and maximum change in mean diameter. The Root Mean Square Deviation was quantified for every strand from the mean diameter of different sections and the average mean diameter.
C. Hair Strand Extension to determine Breakage Point Location
[00098] The hair strands crimped as mentioned above were subjected to tensile extension using a Dia-Stron Mini Tensile Tester MTT175. The hair strands were subjected to a uniform extension at strain rate until strand fractured. The breakage point location was estimated by measuring the two sections of broken hair with a measuring scale (+/- 0.5 mm) and normalizing for the extended length. The breakage location was defined as one of the 10 sections in which hair was segmented using the LSM.
D. Washing hair swatch with a hair damage inducing agent
[00099] For inducing hair damage, the hairs were washed with 15% sodium lauryl ethoxy sulphate (SLES) under controlled conditions as follows:
- 15% SLES Solution (10% of weight of hair tress) was applied to hairs;
- hairs were rubbed in regulated manner by subjecting the hairs with 5 strokes in each side of the hairs in a back and forth motion;
- hairs were rinsed with water by rubbing hairs 10 times on each side in back and forth motions for 1 minute with water; and
- hairs were air dried under 25 ±1 °C and 60±1% RH.
E. Treatment with Hair care product
[000100] Different hair care products were pored over hairs (10% of weight of hair tress for leave-in oil or crème lotions or shampoo and 2% for Rinse-off-Conditioner (RoC)) using pipette. Subsequent to pouring of product, hairs were gently rubbed 5 times on each side in back and forth motions to cover the hair strands evenly with the product. Hairs treated with hair care products were incubated based on the type of the product they were treated within chamber under controlled condition of temperature of about 25oC and the humidity of about 60% RH and
- The incubation time for hair oil was ~15 hours
- The incubation time for Crème Oil was 30 minutes
- The incubation time for Shampoo and RoC was 2 minutes
[000101] Hairs treated with hair oil were washed with SLES or Shampoo as described above.
[000102] Further, hairs from same sample were subjected to 20 cycles of different hair treatments as follows:
- Shampoo Cycles: Shampoo wash followed by drying and combing for alignment of hairs
- RoC Cycles: SLES wash cycles with Rinse-Off Conditioner post SLES wash followed by rinsing
- Shampoo and RoC Cycles: Shampoo followed by RoC application and drying-combing of hairs
- Crème Oil Cycles: Pre-Wash Crème Oil application followed by Shampoo wash
F. Measurement of Hair Strand Mean Diameter Variations’:
[000103] The Mean Diameter Variations’ were measured of the hair strands after the treatment as per the method described in step B.
G. Analysis of Hair Surface Topography:
[000104] The surface topography of the treated hair samples was characterized using Scanning electron microscopy (SEM). Each hair strand was cut from root and tip side to provide two specimens of 3 cm each and was analyzed pre and post treatment. Surface cavities and imperfections observations were made as qualitative measures to validate the quantitative measurements of same hair samples carried out separately. An average count of gaps and micro-cavities were determined in a section of 50×50 µm hair specimens by Image analysis techniques.
H. Weakest Link Determination
[000105] Sample of 300 crimped hair sections from Non-Oil Users were analyzed to understand the correlation between sections where fracture was observed with strand sections with minimum mean diameter and maximum delta change from average mean diameter.
I. Determination of Hair Protection Factor (HPF)
[000106] HPF as a numerical Indicator of Protection accorded by Hair Care Product or treatment Regime was determined based on the Rq.
[000107] The calculation of HPF for product treatment for instance, Hair Swatch treated with 20 Shampoo Cycles is illustrated below:

[000108] In an embodiment the HPF was determined for various product treatments as listed in Table 1:
Table 1: Hair Protection Factor (HPF) for various Hair Care Products used in the study
Rq (µm) HPF
Virgin (untreated hair) 2.10 15.0
SLES-5x 2.46 9.2
SLES-20x 2.98 1.0
RCNO- 20x 2.20 13.4
LLP- 20x 2.61 6.8
Shampoo-20x 2.73 5.0
Rinse of Conditioner (RoC)-20x 2.69 5.6
Shampoo + RoC - 20x 2.61 6.8
Crème Oil + Shampoo - 20x 2.31 11.6

[000109] In the above Table, SLES represents 15% sodium lauryl ethoxy sulphate of cosmetic grade; LLP represents Light liquid paraffin also cosmetic grade; RCNO represents refined coconut oil; and X represents number of cycles or treatment.
[000110] In accordance with the present disclosure the Hair Protection Factor (HPF) can serve as a tool to differentiate various hair care products to control the weakest link progression in hair strands and hence, an indicator for product benefit towards hair strength. The treatment with hair oil (RCNO) showed least variation in mean diameter as evident from minimum Rq value. Consequently, hair oil exhibited the maximum control over the weakest link progression as compared to other products as corroborated from the highest HGF value. Thus, HPF serves as a novel matric indicator of protection accorded by hair care product or treatment regime.

ADVANTAGES OF THE PRESENT INVENTION
[000111] The present disclosure provides a simple and reliable method to evaluate hair and scalp care products by evaluating the hair damage in terms of fracture or propensity to fracture of the hair shaft.
[000112] The present disclosure provides a method for evaluating hair damage, especially by measuring fracture or propensity to fracture of the hair shaft by minimum number of parameters in simple and reliable manner.
[000113] One or more of the evaluations and outcome of the same in accordance with the present disclosure provides a simple and reliable method to assess the effect of various hair care products and tools and thereby help design product to either prevent or recover the damage caused to the hair fiber either by correction and/or management of hair damages. Thus, helping consumers to choose the appropriate product with the desired outcome of hair protection.
[000114] The method for evaluating hair damage, especially by measuring fracture or propensity to fracture of the hair shaft with minimum number of parameters to be determined in accordance with the present disclosure is reliable to be able to determine or predict the hair damage in terms of breakage of hair shaft.
[000115] The method for evaluating hair damage, especially by measuring the weakest link of hair fiber, fracture or propensity to fracture of the hair shaft can be easily implemented at an enterprise level the to predict the effect of a hair care or hair grooming product on hair damage while developing such product or evaluating already existing product.
[000116] The present disclosure provides a new matric HPF that serves as a novel indicator of protection accorded by hair care product or treatment regime.

,CLAIMS:1. A method to evaluate hair and scalp care products by determining change in hair properties on weathering the propensity to fracture of the hair shaft, in which method comprises:
a) sourcing hairs and keeping under controlled environmental conditions of defined temperature and humidity;
b) washing hairs with a hair damage inducing agent and rinsing with water;
c) subjecting hairs to one or more treatment with a hair or scalp care product;
d) incubating the treated hairs under defined temperature and humidity for the predetermined period and rinsing the hair fibers;
e) determining a weakest link progression in terms of a variability in mean diameter of hair strand due to effect of the hair or scalp care product treatment comprising:
i) measuring variations in hair strand mean diameter across length of hair strand including root and tip regions before and after carrying out steps (b) to (d);
ii) determining breakage point location by subjecting the hair strand to extension before and after carrying out steps (b) to (d); and
f) evaluating hair and scalp care products by quantifying the control of the hair damage progression.
2. The method as claimed in claim 1, wherein the sourcing hairs is carried out of a subject not having undergone chemical or thermal treatment(s) to provide a hair sample of virgin category and the subject using a specific hair or scalp care product.
3. The method as claimed in claim 1, wherein the hair damage inducing agent is selected from a surfactant or a shampoo capable of causing damage to hair fiber.
4. The method as claimed in claim 1, wherein the defined temperature ranges from 10 oC to 40 oC (+/- 5oC) and the humidity ranges from 40% to 75% (+/- 5%) relative humidity (RH).
5. The method as claimed in claim 4, wherein the predetermined period ranges from 0.5 minute to 24 hrs.
6. The method as claimed in claim 1, wherein the determination of a weakest link progression includes a step of analyzing hair surface topography, average count of gaps and micro-cavities in a selected section of hair sample.
7. The method as claimed in claim 1, wherein the weakest link progression in terms of a variability in mean diameter of hair fiber is determined as Root Mean Square Variability proportional to the weakest link in hair fiber.
8. The method as claimed in claim 1, wherein the determination of one or more of weakest link progression as a function of time; weakest link progression by in-vivo usage study; and weakest link progression for simulated ex-vivo scenarios is carried out.
9. The method as claimed in claim 1, wherein the quantification of the control of the hair damage progression is determined in terms of the Hair Protection Factor (HPF).
10. The method as claimed in claim 1, wherein the method to evaluate hair and scalp care products by evaluating hair damage by measuring propensity of hair shaft to fracture optionally comprises of:
i) carrying out an evaluation of a single hair shaft by measuring:
one or more parameters selected from a curvature of hair shaft, a cross-section area of hair shaft, an elastic modulus, toughness of single hair shaft, work done at 25%, and breaking stress of hair shaft; or
ii) carrying out an evaluation of hair mass by measuring:
one or more parameters selected from a frizz, a hair volume, a smoothness force, an initial detangling force, and a later detangling force; or
iii) carrying out evaluation based on:
one or more of a hair density, and age of the subject; or
combination of (i), (ii), and (iii).
11. The method as claimed in claim 1, wherein the method to evaluate hair and scalp care products optionally comprises determining change in hair properties on weathering the propensity to fracture of the hair shaft by additional parameter(s) selected from smoothness force, initial detangling force, later detangling force, and hair density.
12. The method as claimed in any one of the claims 1-11, wherein the method to evaluate hair and scalp care products is carried out in a controlled environment by implementing technological tools selected from micrometer, camera, a microscope camera, a camera coupled to an imaging sensor for imaging and image analysis of physical appearance of hair shaft, a comb coupled to a sensor for detecting and measuring force encountered by hair shaft, hair tensile tester, laser scanning microscope; and carrying out procedures for a single or multiple parameter testing(s).
13. The method as claimed in claim 10, wherein the evaluation of the frizz of hair is carried out with the help of a photographic image(s) of the posterior side of the head of the subject showing full breadth and length of hair and determined based on the area outermost to the contour of the complete length and breadth of hair, and end portion of single hair strands protruding out in such outermost defined area.
14. The method as claimed in claim 10, wherein the evaluation of the frizz of hair is carried out with the help of a system including a non-transitory storage device coupled to one or more image receiving component(s), one or more image processing component(s), one or more image based feature extraction component(s), in which one of the feature extraction component being specific to the feature with respect to the protruding out single hair strands, and computing component operable to receive one or more images captured by the camera, receive and execute commands for defining the area outermost to the contour of hair comprising single hair stands protruding out in said defined area, executing the command to adjust the scale and threshold of the photographic image, processing the defined area of the image and determining the frizz by for extracting and detecting the feature in respect of the protruding single hair strands, and computing the number of protruding single hair strands in the defined area.
15. The method as claimed in claim 10, wherein the estimation of the hair volume is carried out with the help of a system including a non-transitory storage device coupled to an image receiving component, one or more of an image processing component(s) capable of processing multiple images and converting them to three dimensional image, and computing component operable to receive one or more images captured by the camera, receive and execute commands for defining the area of hair in each image, executing the command to adjust the scale and threshold and converting the multiple photographic images including the left side, right side and posterior side images of hair into three dimensional image and determining the volume of hair mass.
16. The method as claimed in claim 10, wherein the smoothness force, the initial detangling force, and the later detangling force is determined with the help of a comb coupled to a sensor for detecting and measuring force encountered by hair shaft.
17. The method as claimed in claim 16, wherein the comb for determining the smoothness force, the initial detangling force, and the later detangling force is coupled to a sensor for detecting and measuring force encountered by hair shaft, as well as coupled to a non-transitory storage device, and one or more processors coupled to the non-transitory storage device and a computing device, and the comb is optionally provided with an accessory like a clasp or a clip for securing the specific quantity of hair to uniformly determine the force encountered.