ISO 18861 discusses cosmetics and sun protection test methods with a focus on the percentage of water resistance. ISO 18861 provides a principle that is to compare the sun protection factor (SPF) for a sunscreen product after a period of immersion in water with the static SPF without immersion in water.
ISO 18861 specifies a procedure for evaluating the water resistance retention percentage, by comparing the sun protection factor (SPF) before water immersion (hereafter referred to as the “static” SPF) and after a fixed period of water immersion (hereafter referred to as the “wet” SPF).
ISO 18861 on sun protection test methods is useful for:
The protection that cosmetic products containing organic or inorganic sunscreens provide against sunburn is neither absolute nor permanent. One of the many factors that can have an effect on the level of protection given by these products is water contact. UV absorbers in the formulation can leach out or be physically removed by the washing action in the sea or swimming pool.
ISO 18861 describes the procedure for water resistant percentage calculation, based on the water immersion procedure described in ISO 16217, which is the ratio between before and after bath SPF. discusses test method, calculations, and data handling, test report, simulated swim test device design, test procedure and chronology, and standard reference sunscreen.
EN ISO 18861:2021
ISO 18861:2020