A proposal of a standardized protocol to evaluate waterproof effect of eyeliner and mascara

Eye make-up products must have waterproofing properties to make sure that their colours do not smudge or wash away easily and remain intact despite water or perspiration. Until now, most research has focused on composition and components of make-up products and not on the level of waterproof. This study aimed to find methods to assess the waterproof degree of eyeliners and mascaras and determine the suitability of these methods.

Twenty female subjects were selected to test the waterproof of eyeliners, whereas 20 sets of false eyelashes were used to evaluate the waterproof of mascaras. For evaluating water-resistant properties, after test sites where eyeliners and mascaras were applied were immersed in water and natural drying for over 20 min (not artificial drying by drier etc.), L* value of the eyeliners applied on the forearm before and after the immersions, and intensity analysis values of mascaras applied on the false eyelashes were used to calculate the mean percentage waterproof removal ratio (%WPR). A product was hypothesized to be water resistant if the value for the mean %WPR was ≤50%.

The non-waterproof eyeliners were not waterproof if their mean %WPR was >50%, whereas the waterproof eyeliners were waterproof if their mean %WPR was <50%. For mascaras, the mean %WPR was <50% after 1- to 2-h marks after immersion in water for both non-waterproof and waterproof products. After 3-4 h, the mean %WPR for the non-waterproof mascaras was >50%, rendering them not waterproof, whereas the mean %WPR for the waterproof mascaras was <50%, making them waterproof.

We have evaluated the waterproof properties by analysing photographed images of the test sites where eyeliners and mascaras were applied. Results of the comparison between non-waterproof and waterproof eyeliners and mascaras, and the methods used, in particular, will be found useful in evaluating waterproof of other make-up products.