This test method is utilised to evaluate the soothing and calming efficacy of a test product at different evaluation time intervals. Time intervals may include baseline (BL), one hour (T1Hr), 2 hours (T2Hrs) or 4 hours (T4Hrs) after application This type of testing focuses on a test product’s ability to reduce redness (erythema) and improve skin texture (smoothness).

The instrumental measurement is based upon absorption and reflection of two specific wavelengths and measurement of the two components primarily responsible for the colour of skin: namely melanin and haemoglobin (erythema). Measurements take place in a darkened room. As the quantity of emitted light is defined, the quantity of light absorbed by the skin can be calculated. Multiple readings are taken and the mean determined. Both irritating effects and soothing effects can be quantified.