Field of the invention
The present invention relates to a method for measuring rinsability. In particular, the
invention relates to a quantifiable method of measuring rinsability of a formulation
using instrumental method. More particularly the present invention relates to a
quantifiable method of measuring rinsability of a skin cleansing composition using
instrumental method for evaluation of rinsability.
Background of the invention
Rinsability of skin cleansing formulations is an important attribute of the product as it is
a measure of ease of removal of the ingredients in the formulation from the skin during
wash off. Rinsing off the dirt or remnants of cleansing formulation from skin surface is
essentially important in view that the remnants are sometimes harsh to the skin and pose
topical allergic reactions and various other skin problems. Moreover post wash feel or
rinsability of formulations has been established as an important criterion towards overall
product satisfaction derived by consumers. Optimum rinsability of rinse off
formulations leaves the consumers with moisturized and clean feel. Hence it is needed
to ensure that the surface of skin is rinsed properly without leaving any remnants of
cleansing formulation or dirt. One such method of measuring the rinsing ability of
personal wash formulations is by panel sensorial evaluations; where in the rinsing
ability of the formulation varies with the consumer perception. The method is well
known and used in the art and comprises:
1. Ensuring that the hand of the panelist is free from residues/ impurities by
washing with unperfumed soap or a 5% Sodium Laureth Sulfate (SLES) solution
and dry with tissue paper.
2. Dispensing about 1.5 ml of sample on panelist's hand.
3. Generating foam by rubbing and with addition of appropriate quantity of water.
4. Rinsing the hand under running tap water and dry with tissue paper.
5. Recording the score of individual panelists (1-10 scale) on Likeability of
Rinsability.
6. Analyzing the data statistically to rate the rinsability of the given sample.

In the rating scale the number 1 denotes poor rinsability and 10 denotes good rinsability.
The main disadvantages of the sensory evaluation method include:
1. The results of sensory evaluation vary with consumer perception on the attribute
(in this case it is rinsability), environment conditions and water quality.
2. It is seen that cleansing formulations are not always completely rinsed off from
hands of the panelists. Hence when a second sample is applied to the panelist's
hand for evaluation, the remnants of the first sample, affect evaluation scores of
the rinsability of second sample.
3. Sensory evaluations are essentially non-quantitative. The amount of time taken
to generate foam and thereafter to rinse hand may vary each time a sample is
evaluated and differ for each panelist and hence his evaluation of rinsability of
the sample may vary accordingly.
4. Many a times rinsabilty, as understood by a panelist, may be confused with
conditioning property of the sample. This too may affect the likeability score of
rinsability for a given sample.
5. Sensory evaluations are time consuming. Multiple samples may not be evaluated
correctly by panels at a given time. A gap between 5 consecutive evaluations is
required.
6. Non - Availability of Panel members for sensory evaluation For a given wash
formulation there could be different opinions from the consumers on the rinsing
ability, making the rinsing ability aspect more subjective and difficult to
quantify.
US7650766B2 relates to a washing machine that includes a tub, a sensor operatively
coupled to the tub and configured to sense/detect the conductivity of a fluid in the tub
and a controller operatively coupled to the sensor for controlling the amount of fluid in
the tub based on the conductivity of the fluid. The resistivity/ conductivity sensor senses
the change in conductivity between the wash liquid and the acceptable rinse
concentration. At a preset change limit, such as 99% from final wash to final rinse, the
rinse operation gets terminated with optimum amount of water. The acceptance limit
does not compare against an absolute conductivity measurement, but rather against the
change in conductivity levels, in view that factors such as water purity, contaminants

present, soap brands used, clothing, etc. all have a bearing on the absolute conductivity
level of the wash/rinse solution.
Hamid Mollah, "Cleaning Validation for Biopharmaceutical Manufacturing at
Genentech. Inc. Part 2" : BioPharm International ;2008:21(3)
The non patent literature relates to a cleaning process employed in biopharmaceutical
manufacturing, able to remove materials such as media, buffers, storage solutions, cell
culture fluids, cell debris, non-active pharmaceutical ingredient, and formulations and
concentrations of active pharmaceutical ingredients effectively. Cleaning validation
refers to establishing documented evidence providing a high degree of assurance that a
specific cleaning process will produce consistent and reproducible cleaning results that
meet a predetermined level. This prior art further discloses that visual inspection and
surface Fourier transform infrared spectroscopy (FTIR) are sometimes called "real"
direct surface sampling while rinsate sample testing for pH, conductivity, total organic
carbon (TOC), bio burden, and endotoxin are indirect testing methods. Both direct and
indirect sampling methods should be used to measure residues in cleaning validation.
Detergent residue testing guidelines from ALCONOX (available online at
www, alconox. com)
The non-patent literature relates to a manual describing test procedure that is suitable
for detecting detergent residues resulting from improper rinsing and can be used to meet
laboratory accreditation guideline. Alconox discloses a standardized methodology to be
followed for detecting detergent residues using a pH Meter, pH indicator, or test Kit.
This prior art also discloses a procedure to use conductivity meter and deionized water,
sensitive to ionic detergent residue present in rinse water that has passed through a
pipette. The method involves the measurement or recording of conductivity with
calibrated conductivity meter that reads in the range of at least 0.1 µS/cm to 100 µS/cm
at 25° C. An increase of 0.5µS/cm or less is indicative of no significant detergent
residue.
DRAG AN M.et.al„ Chemical Industry & Chemical Eneineerine: 2011:17 (1) 39-44

The non-patent literature discloses that cleaning agents often consist of a mixture of
various surfactants which are in a highly diluted state after the water rinsing procedure
has been completed. This makes it difficult to find appropriate analytical methods that
are sensitive enough to detect the cleaning agents. In addition, it is advantageous for the
analytical methods to be simple to perform and to give results quickly. Accordingly the
study focuses on comparative analyses of three different non-specific analytical
methods: visual detection of foam, pH and conductivity measurements for detecting the
cleaning agent residues after cleaning. The analyses were performed on different
dilutions of the cleaning agents Bactericidal Hydroclean and Tickopur R33 and the
results demonstrated that the conductivity measurement is the most appropriate method
which enables to detect concentrations of cleaning agents down to 10 µg/ml. This prior
art also describes that although semi quantitative, visual method for foam detection is
more sensitive, as it is easy to perform and gives a quick result without any requirement
of expensive instrumentation.
Prior art reported many direct evaluation methods such as visual inspection method,
surface Fourier transform infrared spectroscopy (FTIR), sometimes called "real" direct
surface sampling method and some indirect evaluation methods such as testing pH,
conductivity, total organic carbon (TOC), bio burden, and endotoxin levels of rinsate
samples. However none of the above methods quantitatively determines the correlation
of sensory evaluation method with that of instrumental evaluation method involving the
conductivity measurements of the rinse fluid samples.
Generally, it is very difficult to obtain a workable correlation between sensory studies
and instrumental methods essentially because sensorials are person specific. Further
unlike the rinsability of formulations from other substrates, rinsability from human skin
is even more specific. This is because of various factors such as nature of skin (skin
differs from person to person), formulation ingredients, likeability and variation in
rinsed-off feel (Different people may perceive rinsability differently). Preference of
rinsability differs with people. Hence it is even more difficult to correlate an
instrumental method with a sensorial method.

Therefore there is a need to develop an quantitative method for measuring rinsing
ability of wash formulations which not only establishes correlation between sensory
evaluation and instrumental evaluation methods but also enables to screen larger set of
partial/full formulations during development and significantly reduces the overall time
required for product development cycle, such that the dependency on conventional
sensory evaluation method can be completely reduced.
There is also a need for a simple instrumental method to evaluate the rinsability of
formulations that is readily applicable to industry and which provides results that are in
correlation with the consumer panel sensory evaluations.
Object of invention
An object of the present invention is to overcome the drawbacks of the prior art.
Another object of the present invention to provide a quantitative instrumental method
for evaluating the rinsing ability of formulation.
Yet another object of the present invention is to provide a quantitative instrumental
method of evaluating rinsability of a cleansing formulation.
Still another object of the present invention is to provide a quantitative instrumental
method of evaluating rinsability of a wash formulation.
Brief Description of the Accompanying Drawings
Figure 1 illustrates comparative post wash conductivity value tested for three products
Figure 2 illustrates panel sensory evaluation (scores in 1 - 10 scale) for rinsability
Figure 3 illustrates comparative results of the conductivity method and consumer
sensorial evaluation

Detailed description of the invention
The present invention provides a quantifiable method for measuring rinsability of
formulations.
The term "Sensory evaluation of rinsability" as used herein refers to any scientific way
of measuring and analyzing the wash-off behavior of the personal care cleansing
products as they are perceived by the consumers.
The term "consumer panel sensory evaluation" as used herein refers to a systematic way
of measuring and analyzing the sensory attributes of cleansing products and or wash
products as they are perceived by section of the people for whom the product is
intended in the market.
The invention provides a method for measuring rinsability of formulations that is based
on instrumental method. A method of measuring rinsability of a formulation
comprising:
a) Applying 0.1 to 1.0 g, preferably 0.5g of the formulation on a
predetermined skin area of panel member;
b) Rinsing the skin area of step a) with 100 to 500 ml, preferably 200ml of
demineralised water;
c) Rinsing the washed skin area of step b) with 25 to 200 ml, preferably 100
ml of demineralised water (Post wash water) and collecting water; and
d) Measuring conductivity value of post wash water collected in step c) and
comparing it with standard conductivity score card to obtain the
rinsability rating of the formulation.
The conductivity value of the collected water samples are to be compared against the
standard conductivity score card given in table 1 for ranking them on rinsability.



It has been found out by the inventors that - on following the above stated procedure -
an obtained conductivity value of above 70 uScm-1 relates to poor rinsabilty as per the
sensory method; a conductivity value of 50-70 uScm-1 relates to satisfactory rinsability
rating as per the sensory; and a conductivity value of below 50 uScm-1 relates to a good
rinsability rating as per the sensory ratings. The method of the present invention is
readily applicable to industry and provides results that are in correlation with the
consumer panel sensory evaluation.
In one of the embodiments of the invention the predetermined area is rectangular in
shape and ranges from 6X5 to 4X3 cms. Preferably the area is 5X4 cms. As may be
understood by a person skilled in the art, the predetermined area is non limiting and may
be altered suitably without affecting the scope of the invention.
In another embodiment of the invention, the skin area is the forearm of the panel
member. Again the area is non-restrictive to the scope of the invention and may be
suitably altered without changing the sum and substance of the invention.
An embodiment of the present invention provides a simple instrumental method to
evaluate the rinsability of cleansing formulations by measuring the conductivity values
of post wash solutions. Cleansing formulations are products used to remove dirt, oils or
pollutants from the skin. They are generally combinations of fatty acid soaps and / or
surfactants with the optional presence of conditioners, moisturizers, skin benefit agents
etc.
The process steps for evaluating rinsability of cleansing formulation comprise:
1. Applying 0.1 to 1.0 g, preferably 0.5g of sample (cleansing formulation) on a
rectangular area on the forearm of panel member. The rectangular area ranges
from 6 X 5 to 4 X 3, particularly of 5 X 4cm.
2. The rectangular area of step 1 was rinsed with 100 to 500 ml preferably 200ml
of Demineralised water and the rinsed water is discarded.

3. The washed rectangular area of step 2 was rinsed with 25 to 200 ml, preferably
100 ml of Demineralised water (Post wash water) and water was collected.
4. Conductivity values of post wash water collected in step 3 is measured and
compared with standard conductivity score card to obtain the rinsability rating of
sample.
The conductivity value of the collected water samples are to be compared against the
standard conductivity score card given in table 1 for ranking them on rinsability.
As one of its embodiments the invention provides a method that is more advantageous
over sensory assessment method as it is a simple and time efficient method minimizing
the dependency on time consuming sensory evaluation method and evaluates large
number of samples in short duration. For instance the panel sensory evaluation (10
panels) of five set of products on rinsability requires two days for completion of
analysis whereas conductivity method according to the present invention takes a
maximum of 4 hours for completion of evaluations.
Another embodiment of the present invention provides a process for evaluating the
rinsability of wash formulations. The wash formulations may be defined as consumer
care products used to remove dirt, oils or pollutants from the skin, hair, keratinous or
fibrous products. Different types of wash formulations available are hard surface
cleansers, laundry products, kitchen care products and the like. The wash formulations
are generally combinations of fatty acid soaps and/or surfactants with the optional
presence of conditioners, moisturizers, skin benefit agents etc. The process for
evaluating the rinsability of wash formulations comprises the following steps.
1. In the first step sample is applied on the skin surface of panelist. The amount of
sample applied ranges from O.10gms to 1.0 gms.
2. In the next step, the sample which was applied in the skin surface panelist is
washed with de-mineralized water. The amount of de-mineralized water used in

the second step ranges from 100 ml to 500 ml; preferably 200 ml of water may
be used.
3. The previous step is again repeated with a lesser quantity of de-mineralised
water. This water is then collected in a beaker. The amount of de-mineralized
water used in the third step ranges from 25ml to 200 ml; preferably 100 ml de-
mineralized water may be used.
4. The conductivity of the post wash water is measured and is compared with the
standard conductivity score card to obtain the rinsability rating of sample.
The conductivity value of the collected water samples are to be compared against the
standard conductivity score card given in Table 1 for ranking them on rinsability.
In one of the embodiments of the present invention, cconductivity is measured using
digital conductivity meter. The process is conventional method and may be defined as
follows:
a. Take around 20 ml of a sample solution, for which conductivity needs to be
measured, in a beaker.
b. Immerse electrode of the conductivity meter in the sample solution.
c. Note down the value of conductivity displayed in the conductivity meter
The digital conductivity meter may be suitably replaced with any other instrument or
method for checking the conductivity value of the post wash water collected. Such
methods and instrument may therefore without limitation fall within the scope of the
present invention. Here it may be noted that the inventive merit of the present invention
does not lie in the use of conductivity meter rather it lies in evaluating rinsability of a
given personal wash formulation using conductivity meter or any other instrument that
can test conductivity. Measuring rinsability using digital conductivity meter is only one
of the embodiments of the present invention.

It may also be stated that merely by checking the conductivity of a personal wash
formulation, it may not be possible to interpret rinsability of a given formulation. The
inventors have found a unique method and correlation whereby a working correlation
has been achieved between an instrumental method and sensory study for evaluating
rinsability.
Here the amount of personal wash formulation taken for conducting the test, the area of
skin whereon it is applied, volume of rinsing water, stage at which the rinsed water be
collected to conduct conductivity studies are all important to the correct evaluation of
rinsability.
It has been found by the inventors that on following the method of the present
invention - an obtained conductivity value of above 70 uScm-1 relates to poor
rinsabilty as per the sensory method; value of 50-70 uScm-1 relates to satisfactory
rinsability rating as per the sensory ;and a value of below 50 fiScm-1 relates to a good
rinsability rating as per the sensory ratings. This correlation works across formulations,
irrespective of the different ingredients that any given formulation may comprise.
Non limiting examples of samples that can be evaluated using the method of the present
invention include but are not limited to Soap, Shower Gel, Body Wash, Face Wash,
Hand Wash, hair cleansing formulations, Shampoo, hair care-rinse off compositions,
skin cleansing formulations, rinse-off skin care formulations, laundry detergents, hard
surface cleansers, dish washing agents etc.
The present invention is now illustrated by way of non-limiting examples.
Example 1: Working example showing the merit and need of the present invention
Market Sample A was evaluated for rinsability based upon
a. Sensory evaluation of rinsability as done conventionally in the art; and
b. Instrumental method of the present invention.
Process followed is as follows:
Sensory process:

1. Ensure that the hand of the panelist were free from residues/ impurities by
washing with unperfumed soap or a 5% SLES solution and dried with tissue
paper.
2. Dispense about 1.5 ml of sample A on panelist's hand.
3. Generate foam by rubbing & with addition of appropriate quantity of water.
4. Rinse the hand under running tap water and dried with tissue paper.
5. Recorded the scores of 12 individual panelists (on a 1 - 10 scale) on Likeability
of Rinsability.
In the rating scale the number 1 denotes poor rinsability and 10 denotes good rinsability.
The rinsability scores obtained from the 12 individual panelists are provided in table 2.
Instrumental method:
1. 0.5g of sample A was rubbed on rectangular area of 5 X 4cm on the forearm of
panel member.
2. The rectangular area of step 1 was rinsed with 200ml of Demineralised water
and the rinsed water is discarded.
3. The washed rectangular area of step 2 was rinsed with 100 ml of Demineralised
water (Post wash water) and water was collected.
4. Conductivity values of post wash water collected in step 3 was noted as 115.
This was compared with standard conductivity score card to obtain the
rinsability rating of sample as "Poor rinsability".
The rinsability scores obtained from the 12 individual panelists are provided in table 2
given as below.



It is observed that the likability score (on a scale of 1-10) on sensory evaluation vary
with each panelist from a value of 4 to 8. Whereas the conductivity value from the
Instrumental Method of the present invention provides a clear indication that the
rinsability of the given sample is not acceptable and hence needs to be improved. The
experiment shows that there is need for an instrumental method more so because panel
scores at all times may not be uniform and may not be clearly indicative of correct
rinsability value.
Example 2: Negative example
Evaluation of rinsability as per the instrument method of the present invention was
carried out by altering the method and by rinsing the predetermined skin area with
higher amount of water.
1. 0.5 g of sample SLES 20% was rubbed on rectangular area of 5 X 4cm on the
forearm of panel member.
2. The rectangular area of step 1 was rinsed with 600 ml of Demineralised water
and the rinsed water is discarded.
3. The washed rectangular area of step 2 was rinsed with 300 ml of Demineralised
water (Post wash water) and water was collected.
4. Conductivity values of post wash water collected in step 3 as measured was 42

5. Conductivity value of 42 relates to good rinsability as per the standard
conductivity score card of the present invention.
Sensory process:
1. Ensured that the hand of the panelist were free from residues/ impurities by
washing with unperfumed soap or a 5% SLES solution and dried with tissue
paper.
2. Dispensed about 1.5 ml of SLES 20% on panelist's hand.
3. Generated foam by rubbing & with addition of appropriate quantity of water.
4. Rinsed the hand under running tap water and dried with tissue paper.
5. Recorded the score of 12 individual panelists (1 - 10 scale. ) on Likeability of
Rinsability. The average score as obtained was 5.43 which is not a good
rinsability score as per sensory evaluation.
In the rating scale the number 1 denotes poor rinsability and 10 denotes good rinsability.
It was noted that when the conditions critical to the instrumental method of evaluation
i.e. the amount of water taken for rinsing the designated area (in step 2 and 3) was not
met, rinsability score as obtained from the instrumental method did not correlate to
sensory Iikability score.
Example 3: process for evaluating the rinsability of wash formulations
The process of evaluating the rinsability of wash formulations comprises:
1. Applying 0.5g of wash formulation at an area of 5 X 4cm on the skin surface
of panelist;
2. Rinsing the wash formulation applied skin surface of panelist of step 1, with
200ml of de-mineralized water; and
3. Re-rinsing the rinsed surface of step 2 with 100 ml of de mineralized water
(Post wash water) and collecting the water in a beaker; and
4. Measuring the conductivity values of post wash water and comparing the
same with standard conductivity score card to assess rinsability rating of
wash formulation.

Example 4: Study comparing the conductivity value and rinsability rating
obtained from instrumental method of the present invention with the rinsabiIiry
likeability score as per panel sensory evaluation method for three products
Four samples - 1TCSG1, MarketSGl, MarketSG2, and SLES 20% were taken. The
samples were compared in post wash conductivity evaluation for rinsability and the
results are shown in Figure-1. The process followed for the analysis is as follows.
1. Applying 0.5g of sample ITCSG1 at an area of 5 X 4cm on the skin surface of
panelist;
2. Rinsing the sample applied skin surface of panelist of step 1, with 200ml of de-
mineralized water; and
3. Re-rinsing the rinsed surface of step 2 with 100 ml of de mineralized water (Post
wash water) and collecting the water in a beaker;
4. Measuring the conductivity values of post wash water and comparing the same
with set standard to assess rinsability of sample.
5. Repeat the same procedure for recording the conductivity of the MarketSGl,
MarketSG2, and SLES 20%.
The conductivity value of 70 u Scm-1 and above denotes poor rinsability, 50 - 70
|iScm-l denotes satisfactory rinsability and 50 |iScm-l and below denotes good
rinsability.
Panel sensory evaluation (scores in 1 - 10 scale) for rinsability (2)
The experimental process carried out comprises the following steps
1. Ensure that the hand of the panelist is free from residues/ impurities by washing
with ITCSG1 solution and dry with tissue paper.
2. Dispense about 1.5 ml of ITCSG1 on panelist's hand.
3. Generate foam by rubbing & with addition of appropriate quantity of water.
4. Rinse the hand under running tap water and dry with tissue paper.
5. Record the score of individual panelists (1-10 scale) on Likeability of
Rinsability.

6. Repeat the same procedure with 10 panelist members for all the products viz.
MarketSGl, MarketSG2 and SLES20%.
7. Analyze the data statistically to rate the rinsability of the given sample.
In the rating scale the number 1 denotes poor rinsability and 10 denotes good rinsability.
The results of the analysis demonstrated that the sample ITCSG1 shows a conductivity
of 40 uScm-1 which is a good rating for rinsability as per the instrumental method of the
current invention. The same is confirmed by sensory evaluation where a score of 6.7
refers to good rating. Similarly the samples Market SGI and Market SG2 gives a
conductivity value below 50 uScm-1 which is also confirmed as a good rating as per
sensory evaluations. SLES 20% gives a conductivity value above 70 uScm-1, a poor
rating for rinsability as per the instrumental method, which is also confirmed as a poor
rating as per sensory evaluations also. Thus whereas a conductivity value of 50 uScm-1
and below relates to a good rinse off behavior, values above 70 uScm-1 conductivity
relate to poor rinsabiltiy (Values between 50 to 70 uScm-1 can be considered as
Satisfactory). As may be noted, a clear correlation is seen between the conductivity
method and the consumer sensorials. Hence the instrumental method of the present
invention provides a simple and time efficient method of evaluating the rinsability of
rinse-off product formulations without undergoing person specific sensory evaluations
at all times.
Example 6: Comparative results of the conductivity method and consumer
sensorial evaluation
Two sets of evaluations were done covering range of products from market and ITCs
products under development. Sensory evaluation on each of the products was carried
out as follows:
1. Ensured that the hand of the panelist were free from residues/ impurities by
washing with unperfumed soap or a 5% SLES solution and dried with tissue
paper.
2. Dispensed about 1.5 ml of sample (ITCSG1) on panelist's hand.
3. Generated foam by rubbing & with addition of appropriate quantity of water.

4. Rinsed the hand under running tap water and dried with tissue paper.
5. Recorded the score of individual panelists (1-10 scale) on Likeability of
Rinsability.
The process was repeated for MarketSGl, MarketSG2, SLES 20%, 1TCSG2, ITCSG3,
MarketSG3, ITCSG4, MarketSG4, MarketSG5, MarketSG6, ITCSG5, ITCSG6 and
ITCSG7.
Rinsability evaluation as per the instrumental method of the present invention was also
carried out for each of the samples as follows:
1. 0.5g of sample (ITCSG1) was rubbed on rectangular area of 5 X 4cm on the
forearm of panel member.
2. The rectangular area of step 1 was rinsed with 200ml of Demineralised water
and the rinsed water is discarded.
3. The washed rectangular area of step 2 was rinsed with 100 ml of Demineralised
water (Post wash water) and water was collected.
4. Conductivity values of post wash water collected in step 3 is measured and
compared with standard conductivity score card to obtain the rinsability rating of
sample.
5. The process was repeated for MarketSGl, MarketSG2, SLES 20%, ITCSG2,
ITCSG3, MarketSG3, ITCSG4, MarketSG4, MarketSG5, MarketSG6, ITCSG5,
ITCSG6 and ITCSG7.
The likeability score from sensory evaluation and rinsability rating from the
instrumental method obtained is mentioned in Table 3 given as under



Result: The comparative results of the conductivity method and consumer sensorial
evaluation results of all the three sets of evaluations results are shown in Figure 3.
Samples, SLES 20% and Market SG5 which exhibited highest post wash conductivity
are also one of the samples having lower scores in consumer sensorial. The data
confirms a clear correlation established between the conductivity method to the
consumer sensorial as seen from the graph. For example the sample MarketSG5 shows
correlative results in the above case.
Observation: MarketSG5 showed poor rinsability rating (as per conductivity method)
and poor rinsability as per consumer sensorial evaluation. The data received confirmed
a clear correlation established between the conductivity method to the consumer
sensorial.

WE CLAIM:
1. A method of measuring rinsability of a formulation comprising:
a) Applying 0.1 to 1.0 g, preferably 0.5g of the formulation on a
predetermined skin area of panel member;
b) Rinsing the skin area of step a) with 100 to 500 ml, preferably 200ml of
demineralised water;
c) Rinsing the washed skin area of step b) with 25 to 200 ml, preferably 100
ml of demineralised water (Post wash water) and collecting water; and
d) Measuring conductivity value of post wash water collected in step c) and
comparing it with standard conductivity score card to obtain the
rinsability rating of the formulation.

2. The method as claimed in claim 1, wherein amount of said formulation ranges
from 0.1 to 1.0 gms.
3. The method as claimed in claim 1, wherein amount of said de-mineralized water
ranges from 125 to 700 ml.
4. The method as claimed in claim 1, wherein predetermined skin area is
rectangular.
5. The method as claimed in claim 1, wherein predetermined skin area is on the
forearm of panel member.
6. The method as claimed in claim 1, wherein formulation is a formulation.
7. The method as claimed in claim 1, wherein formulation is a wash formulation.
8. The method as claimed in claim 6, where in the said formulation is selected
from soap, shower gel, body wash, face wash, hand wash, hair cleansing
formulations, shampoo, hair care-rinse off compositions, skin cleansing
formulations, rinse-off formulations.

9. The method as claimed in claim 1, which is adapted to significantly screen large
number of samples in a short duration with results that show better evaluation of
rinsability than with the results from consumer panel sensory evaluations.

ABSTRACT

A quantitative method of measuring rinsability of a formulation is provided by measuring the conductivity of the post wash water.