Field of the Invention:
The present invention relates to measuring rinsability and cleansing. More particularly the
present invention relates to kits measuring rinsability parameter and end point of cleansing of
any wash off product.
Background of the Invention:
Optimum rinsability is an important parameter that is considered by the end consumers, while
buying a rinse off formulation. It is the unique desirable feature which hinges on the balance
between cleanliness and post wash smooth feel (obtained due to deposition of actives from the
formulation). Whereas on substrates other than human skin, rinsability may be equivalent to a
mere removal of surfactants, soaps or dirt, on the human skin surface, rinsability relates to that
desirable feel wherein skin is perceived to be clean yet not dry. "Perception" is a very difficult to
be quantified. That is essentially because perception varies from person to person and from time
to time. In personal care business, it is very essential to correctly judge the post wash clean feel
offered by a product as it directly relates to the choice of selection of the end product in market.
The function of a cleansing formulation is primarily to cleanse, condition, moisturize and if
possible deliver some benefit agents/actives to the skin. Cleansing composition basically
comprises of surfactant, thickeners, benefit agent/actives and other suitable components. During
use of cleansing product consumers mainly expect that the product should cleanse, moisturize
foam and finally rinse off easily from the skin surface.
Rinsability is an important parameter with respect to wash off products. Methods to evaluate
rinsability of wash off product present in the state of the art mostly involve customer/panelist
evaluation. Such methods are subjected to various limitations like biasness, person to person
variation, and statistical errors during data evaluation.
Mitchell S. et.al, Soap and detergent bar rinsability; j. Soc. Cosmet. Chem., (1986) 37, 89-
97., relates to studies on the role of cleansing bars in skin irritancy based on their pH and
composition. This prior art teaches that rinsability factor is ignored by chamber style tests but
seems to be significant in usage experience and attempts to understand the differences seen in
chamber and use testing, by analyzing 18 common soap, combats, and syndet bars for their
rinsing characteristics, which were compared to their irritancy potential. The relative rinsabilities
of the products were determined photographically and spectrophotometrically using soap
solutions spiked with fluorescein dye. The test involves application of dye-containing soap
solutions to the forearms of volunteers, worked into lather, and rinsed uniformly. The residues
were then either photographed or extracted from the skin and quantified spectrophotometrically.
The results of this study demonstrated that there are significant differences in rinsabilities among

the products tested. Deodorant bars, regardless of composition, rinsed poorly. Facial bars and
"mild bars" tend to have superior rinsabilities.
K. P. ANANTHAPADMANABHAN, K. K. CHAN, X. LEI, and M. P. ARONSON, on the
use of fluorescein as a probe to monitor anionic surfactant rinsability from skin. J.
Cosmest.c i., 49, 69-88 (March/April 1998) teaches the use of fluorescence for measuring
rinsability that will give misleading results because solubility of fluorescents dye (fluorescein)
used in this article depends on surfactant type. So a product having different surfactant type will
have different rinsability in comparison to others. It discloses that fluorescein does not track the
binding of surfactants to the skin and, thus, cannot measure intrinsic interactions between a
cleansing composition and skin. Since fluorescein does not break down into micelles, it also
cannot track down the location of the surfactants.
Although evaluation methods which helps in evaluating rinsability with respect to detergents and
bar soaps used for utensil cleaning were reported in the prior art, these evaluation formats cannot
be applied to wash off products used for skin cleansing, as the surface of skin varies from person
to person. All the methods that are available so far are based on evaluating sensory factors such
as cleansing, foaming and rinsability involving customer feedback. There is no standard method
in the state of the art that can provide a quantitative measure of rinsability and cleansing property
for any wash off formulation.
Therefore there is a need to develop an improved method that can address the problem of prior
art and can evaluate rinsability and cleansing in a quantitative manner. The present invention
provides a quantifiable method of evaluating rinsability of a given formulation and also helps in
establishing the correlation between the actual cleansing action and panelist feedback and will
help to determine consumer mind when cleansing and rinsability is involved.
Object of the Invention
It is an object of the present invention to overcome the drawbacks of the prior art.
Another object of the present invention is to provide a quantitative method for measuring
rinsability and cleaning of any wash-off products.
Yet another object of the present invention is to provide a method that can simultaneously
measure the rinsability and cleansing of any wash-off products.
Another object of the present invention to provide a kit that can measure simultaneously the
rinsability and cleansing parameter of any wash off product.
Yet another object of the present invention to establish a one-to-one correlation between
consumer feedback and actual measurement of the rinsability and cleansing parameter of wash
off products

Summary of the present invention
An aspect of the present invention provides a quantitative evaluation and measuring of rinsability
comprising steps of
a. preparing a dilute solution of surfactant or formulation in a beaker containing distilled
water;
b. Taking sets of beakers containing distilled water in each;
c. washing of hands and recording the feedback of a group of panelists regarding the residue
or slippery feeling;
d. applying two different diluted surfactant or formulation solution in hands and recording
the feedback of a group of panelists regarding the residue or slippery feeling
e. washing of hands in separate beakers and repeating the step till the hands are completely
clean;
f. measuring surface tension of water collected from step "c" to step "e";
g. measuring the weight of the fixed number of water drops of all liquids obtain form step
"c" to step "e";
wherein surface tension value of rinsed water is approximately 50 mN/m.
Brief Description of Accompanying Figures
Figure 1 illustrates rinsability plot with number of washes in the X axis and surface tension of
the samples in the Y axis.
Figure 2 illustrates the method/procedure of carrying out the present invention.
Figure 3 shows the measurement of the weight/volume of fixed number of drops of water using a
burette as obtained from solutions from step 1 to step 3 (as described in Figure 2) of carrying out
the present invention.
Figure 4 describes the different kits of the present invention.
Figure 5 describes Kit 1 in detail.
Figure 6 describes Kit 2 in detail.
Figure 7 describes Kit 3 in detail.
Figure 8 describes Kit 4 in detail.

Figure 9 describes the rinsability profiles of various surfactants.
Figure 10 describes the graphical representation of rinsability profiles of various Face wash
products
Figure 11 describes the rinsability of a face wash formulation from drop volume/weight
measurements.
Figure 12 describes the graphical representation of rinsability analysis of various face wash
products measured by drop volume/weight measurement
Figure 13 illustrates an instrument for measuring surface tension using drop weight/volume
method
Figure 14 illustrates rinsability plot
Detailed description of the invention:
The present invention provides methods and kits to measure rinsability parameter of any wash
off product. The process provided in the present invention measures rinsability accurately,
quantitatively and is free from any personal variation or biasness. End point of the cleaning or
rinsability is detected by the consumer and the same is measured by the instrument and thus one
to one correlation of consumer feedback and actual measurement can be established.
Rinsability is the measure of number of washes required for washing off of any cleansing
product post application on a substrate such as the human skin. The end point is determined by
the customer feedback, when they feel their hand/skin is completely cleaned and rinsed. A
typical rinsability plot is plotted in Figure 1 with number of washes in the X axis and surface
tension of the samples in the Y axis. It is evident from the graph of Figure 1 that when the
consumer feels that their hands are completely clean and rinsed, then the surface tension of the
rinse off water is near the surface tension of the pure water. The end point is determined by the
surface tension of the wash off water.
The present invention is carried out in accordance with Figure 2 and Figure 3 and is explained in
the following four steps.
Step 1: Wetting hand in known volume of water taken in a container (Pre-wash with water). The
volume of water varies from 1-2 litres.
Step 2: Dipping the wet hand in known volume of diluted wash-off products taken in a container
and keeping it dipped for some time with constant rubbing of fingers against each other. The

amount of diluted wash-off products in which wet hand is dipped ranges from 1-2 litres. Wet
hands may be dipped in water for around 1-2 minutes.
Step 3: Serially washing hand in known volume, 1-2 liters of pure de-ionized water taken in
different container until one feels hand is clean; step 3 is repeated till one feels the hand is clean
(Post-wash).
Step 4: Measuring the surface tension of the washed liquids as obtained in step 3 or alternatively
measuring the weight/volume of fixed number of drops of water using a burette.
The method of measuring the rinsability and cleaning comprises steps of:
Step 1: Preparing a dilute solution of surfactant or formulation (2% solution) in a 1000ml beaker
containing 500 ml distilled water.
Step 2: Taking five to six sets 1000 ml beakers containing 500 ml distilled water in each.
Step 3 (Pre-rinsing): Asking the panelist to mimic washing of hands by immersing their left and
right hands and rubbing the fingers against each other in first set of water filled in glass beakers
(refer step 2) for about 1 minute and recording their feedback regarding the residue or slippery
feeling.
Step 4 (Product application): Asking the panelist to immerse their hands in two different diluted
surfactant or formulation solution (2% solution) and asking them to rub their fingers against each
other for one minute (mimicking product application) and recording their feedback regarding any
residue or slippery feeling.
Step 5 (Post-rinsing): Asking the panelist to immerse their hands into 500ml distilled water (refer
step 2) in separate beakers and asking them to rub their fingers against each other (mimic
rinsing) for one minute recording their feedback whether they perceives any residue/slippery
feeling on fingers. Continuing the step 5 until panelists do not perceive any residue or slippery
feeling in their hands.
Step 6: Measuring the surface tension of water collected from step 3 to step 5. (Pre-rinsing,
Product application, Post-rinsing).
Step 7: Alternatively measuring the weight of the fixed number of water drops (100) of all
liquids obtain form step 3 to step 5.
Measurement surface tension:

The surface tension of liquid can be experimentally measured by several methods, such as,
Capillary Rise, Drop Volume or Drop Weight, Axiosymmetric Drop Shape Analysis, Wilhelmy
plate/Du Nouy ring method, Captive Bubble, Maximum Bubble Pressure, etc. The current
invention uses two independent surface tension measurement methods (i) Drop Weight/Volume
and (ii) Wilhelmy method.
Experimental procedure for measuring surface tension using drop weight/volume method:
1. A Clean and dry stalagmometer is mounted on the vertical stand.
2. The weight of the empty bottle (mo) is taken/recorded.
3. The beakers filled with distilled water, tubing with rubber bulb is mounted at the top end of
stalagmometer. the bottom end of stalagmometer is immersed into water and is filled up in such
a way that the water level is above the wide part of stalagmometer.
4. Rubber bulb is removed and 20 water drops is collected into the weighing bottle.
5. the mass of the weighing bottle with water is measured to determine the mass of 20 drops.
6. the weighing bottle and stalagmometer is emptied, and are dried for the next measurement.
7. steps 2-6 are repeated for liquids with the unknown surface tension.
8. using the temperature in laboratory, the water surface tension using values from the above
experiments are determined
Experimental procedure for measuring surface tension using Wilhelmy Plate method:
The measurement can be done using any conventional tensiometer manufactured by Kruss,
Dataphysics, Attension (Sigma), Kibron etc. The present invention uses dynamic contact angle
meter and tensiometer (DCAT) from Dataphysics
In this method, a thin plate (usually made of platinum and iridium) is used. It is dipped into the
liquid, whose surface tension is to be measured, the vessel containing the liquid is gradually
lowered and the force measured by the balance at the point of detachment is noted. The force is
coveted to surface tension.
Rinsability is indicated when the surface tension value of rinsed water is approximately 50
mN/m. The value disclosed is derived by the inventors. The details of the formula used for
calculation is detailed in figure 14. Figure 14 shows the representative rinsability plot. The X
axis scales the no of washes and the Y axis scales the surface tension value. Out of the typical
rinsability plot two straight lines i.e. line 1 and line 2 can be drawn from the data point as

depicted in figure. The intersection of the two lines defines a point having Y coordinate ΓR . The
value of ΓR can be calculated using the equation.

wherein,
M1 is the slope of line 1
M2 is the slope of line 2
C1 is the intercept of line 1
C2 is the intercept of line 2
The value of ΓR represents the end point. Rinsability is considered to be achieved, when the value
of ΓR is > 50 mN/m (but this value should not exceed the surface tension of water i.e. 72.8
mN/m at 25 °C)
Advantages of the present invention:
1. This method helps in establishing a link between consumer perception and scientific
measurements.
2. Present method is employed to measure rinsability and cleansing of wash off product
simultaneously.
3. The instruments/kits as per the present invention are easy to operate and can be handled/
operated by a person with minimum skills.
Another embodiment of the present invention provides various kits that can help in evaluation of
rinsability and cleansing of wash of product. The kits are very simple and easy to operate and can
be handled by a person with minimal skill. The four different kits are shown in Figure 4 where
A, B, C and D represent Kit 1, Kit 2, Kit 3 and Kit 4 respectively.
The rinsability measuring kits (Kits 1 to 4) disclosed in the present invention determine the end
point of rinsability. By knowing the end point, one can know the time, when rinsability is fully
achieved which serves as an evaluation parameter for the formulation development and uses. It
can also give a feedback to the machine to stop the flow of water, which in turn reduces water
wastage.

Figure 5 describes Kit 1 in detail. As described in Figure 5, Kit 1 consists of a wash basin (A1), a
graduated "sand clock" type glass measuring cylinder (A2) and a capillary (A3). The glass
measuring cylinder has an arrangement of capillary connecting both cones.
Method of using the Kit 1:
Step 1: Wetting hand in known volume of water (1-2 liters) taken in a wash basin.
Step 2: Dipping wet hand in known volume diluted wash-off products (1-2 liters) taken in
another wash basin and keeping it dipped for 1-2 minutes with constant rubbing of fingers
against each other.
Step 3: Serially washing hand in known volume (1-2 liters) of pure de-ionized water taken in
different wash basins until feeling in the hand is clean; step 3 is repeated till one feels that hand
is perfectly clean.
Step 4: Volume of fixed number of drops of solutions obtained in different wash basins are
measured through graduated "sand clock" type glass measuring cylinder (A2).
Figure 6 describes Kit 2 in detail. Kit 2 consists of a wash basin (B1), a glass funnel (B2), a sleek
internal diameter glass measuring cylinder (B3) and a weighing balance (B4).
Method of using the Kit 2:
Step 1: Wetting hand in known volume of water (1-2 liters) taken in a wash basin.
Step 2: Dipping wet hand in known volume diluted wash-off products (1-2 liters) taken in
another wash basin and keeping it dipped for 1-2 minutes with constant rubbing of fingers
against each other.
Step 3: Serially washing hand in known volume (1-2 liters) of pure de-ionized water taken in
different wash basins until feeling in the hand is clean; step 3 is repeated till one feels that hand
is perfectly clean.
Step 4: Volume of fixed number of drops of solutions obtained in different wash basins are
measured with the help of sleek internal diameter glass measuring cylinder (B3) and weight of
fixed number of drops are measured through weighing balance (B4).

Figure 7 describes Kit 3 in detail. Kit 3 consists of a wash basin (C1), a glass container with an
opening slit at bottom (C2), a height adjustable stand (C3), a drop shape capturing lens
connected to drop shape analyzer C7 (C4), a time counter (C5), a sleek internal diameter glass
measuring cylinder (C6), a drop shape display (C7) and a weighing balance (C8).
Method of using the Kit 3:
Step 1: Wetting hand in known volume of water (1-2 liters) taken in a wash basin.
Step 2: Dipping wet hand in known volume diluted wash-off products (1-2 liters) taken in
another wash basin and keeping it dipped for 1-2 minutes with constant rubbing of fingers
against each other.
Step 3: Serially washing hand in known volume (1-2 liters) of pure deionized water taken in
different wash basins until feeling in the hand is clean; step 3 is repeated till one feels that hand
is perfectly clean.
Step 4: Volume of fixed number of drops of solutions obtained in different wash basins are
measured with the help of sleek internal diameter glass measuring cylinder (C6) and weight of
fixed number of drops are measured through weighing balance (C8). Shape of the drops are
analyzed with the use of drop shape capturing lens connected (C4) to drop shape analyzer (C7).
Time taken for the flow of fixed number of drops is analyzed through time counter (C5).
Figure 8 describes Kit 4 in detail. Kit 4 consists of a wash basin (D1), a glass container enclosing
graduated glass container D3 with capillary D4 at the bottom and measuring glass cylinder with
movable volume indicator (floating ball/mercury, etc) (D2), a graduated glass container (D3), a
capillary with slit opening at the bottom of the measuring glass container D3 (D4) and a sleek
internal diameter glass measuring cylinder (D5).
Method of using the Kit 4:
Step 1: Wetting hand in known volume of water (1-2 liters) taken in a wash basin.
Step 2: Dipping wet hand in known volume diluted wash-off products (1-2 liters) taken in
another wash basin and keeping it dipped for 1-2 minutes with constant rubbing of fingers
against each other.
Step 3: Serially washing hand in known volume (1-2 liters) of pure de-ionized water taken in
different wash basins until feel hand is clean; step 3 is repeated till one feels that hand is
perfectly clean.

Step 4: Volume of fixed number of drops of solutions obtained in different wash basins are
measured with the help of sleek internal diameter glass measuring cylinder (D5).
The present inventors have found that the kits disclosed in the present invention are not just
restricted to rinsability of soap but can be used for any formulation using surfactant. The kits can
also be used in food industry to evaluate complete removal of protein or lipid molecules. In a
manufacturing process rinsability is a primary requirement. This instrument is a valuable kit for
the same. The present invention might be one of the valuable instruments which can find its
application in food, cosmetics, health care and drug industry. Beside this the automated kits can
also be used with attachment for household instrument to ensure end point for cleaning or rinsing
for fabric, dish cleaning, hand washing, body gels is achieved. This can be used as an accessory
for washing process which ensures the minimum requirement of water for the wash-ability.
Quantification of any evaluation parameter with minimum error is always desired as it leads to
better understanding with respect to the performance of product which becomes important during
product designing and also serves as an evaluation standard for already established products.
Rinsability is an important evaluation parameter with respect to wash off formulation employed
in food, cosmetic health care and drug industry. Evaluations of rinsability of wash off
formulation are associated with various drawbacks as it deals with qualitative assessment only
which vary from person to person. Present methods quantify the rinsability parameter so that it
can provide accurate values, which are very significant during product designing and also during
evaluating product against established standards.
The measurement method and the kits disclosed in the present invention can be used for standard
protocol for determining cleansing and rinsing. It has found its applications in the following
industry
Food Industry:
• Complete cleaning and removal of surface active agents (surfactants) of manufacturing
equipment to avoid contamination in finished goods
• Determine the end point of cleansing and rinsing
• Minimize water consumption
Health Care Industry:
• Cleaning and rinsing are the major activities in the health care centers for maintaining
hygienic conditions. Surfactants based cleansers are widely used for the same.
• Determine the end point of cleansing and rinsing
• Minimize water consumption

Pharmaceutical Industry:
• Complete cleaning and removal of surface active agents (surfactants) of manufacturing
equipment to avoid contamination in finished goods
• Determine the end point of cleansing and rinsing
• Minimize water consumption
Cosmetics Industry:
• Complete cleaning and removal of surface active agents (surfactants) of manufacturing
equipment to avoid contamination in finished goods
• Design cleansing/wash-off products having consumer acceptable cleansing and rinsability
• Determine the end point of cleansing and rinsing
• Minimize water consumption
The present invention is now illustrated by way of non-limiting examples.
Example 1:Evaluation of rinsability Parameters for various surfactants
The graphical representation of rinsabilities of two different surfactants, Decyl Glucoside and
Sodium Laureth Sulphate, is shown in Figure 9.
Figure 9 represents rinsability of surfactants DG=Decyl Glucoside; SMCT = Sodium Methyl
Cocoyl Taurate; SLES 1EO = Sodium Lauryl Ether Sulphate (1EO); SLS = Sodium Lauryl
Sulphate; Cetearyl Polyglucoside
Result and observation: The end point was achieved, when the ΓR for all the above case reached
50 mN/m.
Example 2:Evaluation of rinsability for face wash products
The graphical representation of rinsabilities of two different face wash products is shown in
figure 10.
Figure 10 provide rinsability of FW1 = face wash 1; FW2 = face wash 2; FW3 = face wash 3;
FW4 = face wash 4
Inference: The figure shows formulation to formulation variation of rinsability profile.
Result and observation: The end point was achieved when the ΓR for all the above case reached
50 mN/m.
Example 3: Evaluation of rinsability for face wash 5 by drop volume/weight measurements.
Figure 11 shows the rinsability of a face wash 5 formulation from drop volume/weight
measurements.

Result and observation: The end point was achieved when the γR for all the above case reached
50 mN/m.
Example 4: Evaluation of rinsability for various face wash products by drop
volume/weight measurements.
The graphical representation of rinsabilities measured of two different face wash products using
drop volume/weight measurements is shown in figure 12.
Figure 12 provide rinsability FW1 =face wash 1 ; FW2 = face wash 2; FW3 = face wash 3
Inference: The figure shows formulation to formulation variation of rinsability profile.
Result and observation: The end point was achieved when the ΓR for all the above case reached
50 mN/m.
Example 5: Process for evaluation of rinsability profiles for fabric, dish cleaning, hand
washing and body gel products.
Fabric:
Step 1: Preparing a solution of detergent (2% solution) in a bucket containing 5 liters distilled
water.
Step 2: Taking five to six sets bucket containing 5 liters distilled water in each.
Step 3 (Pre-wash): Fabric material is dipped in the bucket containing 5 liters of water by
mimicking washing of fabric for fixed period of time (about 1 to 2 minutes) and recording their
feedback regarding the residue or slippery feeling.
Step 4 (Product application): Immerse the fabric in detergent solution in 5 liters of bucket and
washing the fabric for fixed period of time (about 1 to 2 minutes) recording their feedback
regarding any residue or slippery feeling.
Step 5 (Post-rinsing): Immerse the fabric in bucket containing 5 liters of distilled water (refer
step 2) in separate bucket and asking them to mimic rinsing of fabric for one minute recording
their feedback whether they perceives any residue/slippery feeling on fingers. Continuing the
step 5 until panelists do not perceive any residue, foam or slippery feeling in the fabric.
Step 6: Measuring the surface tension of water collected from step 3 to step 5. (Pre-wash,
Product application, Post-rinsing).
Step 7: Alternatively measuring the weight of the fixed number of water drops (100) of all
liquids obtain form step 3 to step 5.
Dish Cleaning:

Step 1: Taking five to six sets bowl containing 2 liters distilled water in each.
Step 2 (Pre-wash): dish is dipped in the bowl containing 2 liters of water by mimicking washing
of dish for about fixed period of time (about 1 to 2 minutes) and recording their feedback
regarding the residue or slippery feeling.
Step 3: Cleaning the dish with known quantity of dish cleaner.
Step 4 (Product application): Immerse the dish cleaned in step 3 in 2 liters of water containing
bowl and washing the dish for fixed period of time (about 1 to 2 minutes) recording their
feedback regarding any residue or slippery feeling and foam.
Step 5 (Post-rinsing): Immerse the dish in bowl containing 2 liters of distilled water (refer step 4)
in separate bowl and asking them to mimic rinsing of dish for fixed period of time (about 1 to 2
minutes) recording their feedback whether they perceives any residue/slippery feeling or foam.
Continuing the step 5 until panelists do not perceive any residue or slippery feeling or foam in
the bowl.
Step 6: Measuring the surface tension of water collected from step 3 to step 5. (Pre-wash,
Product application, Post-rinsing).
Step 7: Alternatively measuring the weight of the fixed number of water drops (100) of all
liquids obtain form step 3 to step 5.
Hand Wash and Body Wash/Gel:
Step 1: Preparing a dilute solution of formulation (2% solution) in a 1000 ml beaker containing
500 ml distilled water.
Step 2: Taking five to six sets 1000 ml beakers containing 500 ml distilled water in each.
Step 3 (Pre-rinsing): Asking the panelist to mimic washing of hands by immersing their left and
right hands and rubbing the fingers against each other in first set of water filled in glass beakers
(refer step 2) for about fixed period of time (about 1 to 2 minutes) and recording their feedback
regarding the residue or slippery feeling.
Step 4 (Product application): Asking the panelist to immerse their hands in two different diluted
surfactant or formulation solution (2% solution) and asking them to rub their fingers against each
other for fixed period of time (about 1 to 2 minutes) mimicking product application and
recording their feedback regarding any residue or slippery feeling.
Step 5 (Post-rinsing): Asking the panelist to immerse their hands into 500ml distilled water (refer
step 2) in separate beakers and asking them to rub their fingers against each other (mimic
rinsing) for fixed period of time (about 1 to 2 minutes) recording their feedback whether they

perceives any residue/slippery feeling on fingers. Continuing the step 5 until panelists do not
perceive any residue or slippery feeling in their hands.
Step 6: Measuring the surface tension of water collected from step 3 to step 5. (Pre-rinsing,
Product application, Post-rinsing).
Step 7: Alternatively measuring the weight of the fixed number of water drops (100) of all
liquids obtain from step 3 to step 5.
Example 6: Comparative analysis for consumer evaluation (prior art) Versus Instrumental
evaluation (Present invention) methods of rinsiability.
Table 1. Consumer evaluation of rinsability

Five panelists evaluated the face wash 1 and face wash 2 with respect to the rinsability
parameters. The values indicate the number of washes which is required when the panelist feel
that face wash is completely rinsed off.
Table 2. Evaluation of risibility of face washes using the method of present invention


The samples of five panelists from the above the rinsability value were evaluated using the
surface tension method of the present invention. The values indicate the number of washes
required for face wash to be completely rinsed off.
From the above results, it is evident that consumer evaluation (prior art) provide different
rinsability value for the same product. Whereas the current method provide same rinsibility
values irrespective of panelists involved in the evaluation.

We claim
1. A quantitative evaluation and measuring of rinsability comprising steps of
a) preparing a dilute solution of surfactant or formulation in a container/ beaker
containing distilled water;
b) Taking sets of container/beakers containing distilled water in each;
c) washing of hands and recording the feedback of a group of panelists regarding the
residue or slippery feeling;
d) applying two different diluted surfactant or formulation solution in hands and
recording the feedback of a group of panelists regarding the residue or slippery feeling;
e) washing of hands in separate container/beakers and repeating the step till the
hands are completely clean;
f) measuring surface tension of water collected from step "c" to step "e";
g) measuring the weight of the fixed number of water drops of all liquids obtain
form step "c" to step "e";
wherein surface tension value of rinsed water is approximately 50 raN/m.
2. The quantitative evaluation and measuring of rinsability as claimed in claim 1, wherein
said diluted solution is 2% dilution.
3. The quantitative evaluation and measuring of rinsability as claimed in claim 1, wherein
said beaker contains 500 ml distilled water.
4. The quantitative evaluation and measuring of rinsability as claimed in claim 1 is done
with kit 1 comprising a wash basin, a graduated "sand clock" type glass measuring
cylinder and a capillary.
5. The quantitative evaluation and measuring of rinsability as claimed in claim 1 is done
with kit 2 comprising a wash basin, a glass funnel, a sleek internal diameter glass
measuring cylinder and a weighing balance.
6. The quantitative evaluation and measuring of rinsability as claimed in claim 1 is done
with kit 3 comprising a wash basin, a glass container with an opening slit at bottom, a
height adjustable stand, a drop shape capturing lens connected to drop shape analyzer, a
time counter, a sleek internal diameter glass measuring cylinder, a drop shape display and
a weighing balance.
7. The quantitative evaluation and measuring of rinsability as claimed in claim 1 is done
with kit 4 comprising a wash basin, a glass container enclosing graduated glass container
with capillary at the bottom and measuring glass cylinder with movable volume indicator,

a graduated glass container, a capillary with slit opening at the bottom of the measuring
glass container and a sleek internal diameter glass measuring cylinder.
8. A method of using kit 1 as claimed in claim 4 comprising steps of
a) wetting hand in known volume of water taken in a wash basin;
b) dipping wet hand in known volume diluted wash-off products taken in another
wash basin and keeping it dipped for with constant rubbing of fingers against each other;
c) washing hand in pure de-ionized water taken in different wash basins until hand is
clean;
d) repeating step "c" till hand is clean;
e) measuring volume of fixed number of drops of solutions obtained from different
wash basins through said graduated "sand clock" type glass measuring cylinder;
f) calculating surface tension.

9. The method of using kit 1 as claimed in claim 8, wherein said known volume of water is
1-2 litres.
10. The method of using kit 1 as claimed in claim 8, wherein said known volume of diluted
wash off product is 1-2 litres.
11. The method of using kit 1 as claimed in claim 8, wherein said washing of hands is carried
out for 1-2 minutes.
12. A method of using kit 2 as claimed in claim 5 comprising steps of

a) wetting hand in known volume of water taken in a wash basin;
b) dipping wet hand in known volume of diluted wash-off products taken in another
wash basin and keeping it dipped for with constant rubbing of fingers against each other;
c) washing hand in pure de-ionized water taken in different wash basins until hand is
clean;
d) repeating step "c" till hand is clean;
e) measuring volume of fixed number of drops of solutions obtained from different
wash basins through said sleek internal diameter glass measuring cylinder;
f) measuring weight of fixed number of drops through said weighing balance;
g) calculating surface tension.

13. The method of using kit 2 as claimed in claim 12, wherein said known volume of water is
1-2 litres.
14. The method of using kit 2 as claimed in claim 12, wherein said known volume of diluted
wash off product is 1-2 litres.
15. The method of using kit 2 as claimed in claim 12, wherein said washing of hands is
carried out for 1-2 minutes.
16. A method of using kit 3 as claimed in claim 6 comprising steps of

a) wetting hand in known volume of water taken in a wash basin;
b) dipping wet hand in known volume diluted wash-off products taken in another wash
basin and keeping it dipped for with constant rubbing of fingers against each other;
c) washing hand in pure de-ionized water taken in different wash basins until hand is
clean;
d) repeating step "c" till hand is clean;
e) obtaining and measuring the volume of fixed number of drops of solutions in
different wash basins with the help of said sleek internal diameter glass measuring
cylinder;
f) weighing fixed number of drops and measuring through said weighing balance;
g) analyzing the shape of the drops with the use of said drop shape capturing lens
connected to drop shape analyzer;
h) analyzing time taken for the flow of fixed number of drops through said time counter;
i) calculating surface tension.
17. The method of using kit 3 as claimed in claim 16, wherein said known volume of water is
1-2 litres.
18. The method of using kit 3 as claimed in claim 16, wherein said known volume of diluted
wash off product is 1-2 litres.

19. The method of using kit 3 as claimed in claim 16, wherein said washing of hands is
carried out for 1-2 minutes.
20. A method of using kit 4 as claimed in claim 7 comprising steps of

a) wetting hand in known volume of water taken in a wash basin;
b) dipping wet hand in known volume diluted wash-off products taken in another
wash basin and keeping it dipped for with constant rubbing of fingers against each other;
c) washing hand in pure de-ionized water taken in different wash basins until hand is
clean;
d) repeating step "c" till hand is clean;
e) measuring volume of fixed number of drops of solutions obtained from different
wash basins through said sleek internal diameter glass measuring cylinder;
f) measuring weight of fixed number of drops through said weighing balance;
g) calculating surface tension.

21. The method of using kit 4 as claimed in claim 20, wherein said known volume of water is
1-2 litres.
22. The method of using kit 4 as claimed in claim 20, wherein said known volume of diluted
wash off product is 1-2 litres.
23. The method of using kit 4 as claimed in claim 20, wherein said washing of hands is
carried out for 1 -2 minutes.

ABSTRACT

A quantitative evaluation and measuring of rinsability by measuring the surface tension of the
wash off product is provided in the present invention. Further there are four kits provided in the
present invention which helps in the evaluation and measurement of the risability an easy to
operate process. These kits can be handled/ operated by a person skilled in the art.