How is the performance of hair care products tested?

Anti-dandruff performance testing

Dandruff sensory tests are used to determine the effectiveness of anti-dandruff products, and it may be a bit more involved than you first thought! At least 90 participants are recruited with varying degrees of dandruff. They are split into three groups of thirty: one group tests your company’s anti-dandruff product; one group tests a leading anti-dandruff product; and the final group uses a placebo product with no anti-dandruff action. 

Prior to starting the test, trained evaluators section each participants’ head into 9 areas: 3 sections across the front; 3 sections across the middle; and 3 sections across the back. Evaluators then rate the severity of the dandruff using the following scale:

A total score is given out of 45, based on the severity of dandruff. Participants are then given a ‘control’ product with no anti-dandruff action to use twice a week for 3 weeks; this acts as a ‘wash out’ period so that previously used product can’t impact the results. After this wash out period, participants are again rated, allocated to one of the 3 groups, and given product marked A, B, or C. They are then told use that product twice a week for 6 weeks, before attending a final evaluation just prior to their next wash. 

Each participants final results are then plotted in a graph to monitor effectiveness of the test product against the control and competitors’ brand. Statistical significance is evaluated using a ‘one-way analysis of variance’ to test for significance; and this then enables the performance of your brands anti-dandruff product to be compared to a brand leader as well as placebo, and to also provide claims of improvement over a 6 week period. 

Watch how to make anti-dandruff shampoo here.
Watch how to make a natural anti-dandruff scalp serum here. 
 

Half-head performance testing

Half head tests are used to compare various performance characteristics of two products, such as: 

• how clean each shampoo gets the hair: for example, may use numerical scales, rating level of cleaning from 0 – 5; or may ask evaluators to pick which works best
• how soft each conditioner makes the hair feel: for example, may use graphical or verbal scales ranging from not soft to very soft; or may ask evaluators to pick which works best
• how easily each spray-in conditioner detangles the hair: for example, may use verbal scales to rate ease of combing; or may ask evaluators to pick which works best

Half-head performance tests require 20-30 participants, and should involve careful selection to make sure participants all have similar condition and hair types prior to starting (for example, dry, chemically treated hair; or oily hair, as well as type 1, 2, 3 or 4. Read more about hair types differ here).

One product is applied to one half of the head (e.g. left hand side) while the other product is applied to the other (e.g. right hand side). Trained hairdressers are typically used to ensure product is applied equally without bias. 
 
Trained evaluators are then used to rate the performance of each product using a particular rating scale. Once evaluation is complete, results for each product are totalled and the difference between results calculated. 

Alternatively, evaluators or participants may be asked to select which product works best, and give comments about performance and preference. Photos may also be used to show how performance differs between each side of the head, particularly where the results are easily visible; for example, colour protection performance, styling hold or anti-frizz solutions. 

Watch how to make anti-frizz serum here. 
Watch how to make hair colour protection oil here.
 

Curl retention tests

The styling and curl holding power of hair care products is usually tested using curl retention tests. Curl retention tests use at least 12 matching hair tresses, split into two groups of six. The tresses are shampooed, conditioned, rinsed and dried in exactly the same manner and their dried length measured.

One product is applied to six tresses, while another product is applied to the other six tresses. Skilled hairdressers are usually involved to make sure the application method is consistent, and the environment must be controlled for quantity, temperature and humidity. 

The tresses are then placed in an apparatus called a curl former and left to set for the same period of time. The tresses are then removed from the curl former and measured for curl length; they are then placed in a controlled environment cabinet, set at a pre-determined temperature and relative humidity e.g. room temperature and 75% RH. 

After a set time (for example, 6 or 8 hours), the tresses are removed from the humidity chamber and measured. The length of the tresses is then calculated as a percentage of their original length, and the mean calculated for each group of six. A ‘t-test’ is used to obtain statistical results and the % curl retention may also be used to support claims of how well the styling product holds the style in place. 

Watch how to make curly hair crème here.
Watch how to make natural hair spray and gel here. 

So, there you have it, that’s how hair care products are performance tested to support claims and provide the required evidence. Now it’s over to you to get creating these amazing hair styling and performance products, then get testing to boost the claims made by your brand. 

Happy formulating!