It is recommended to perform a sensitivity test at least 48 hours before colouring your hair, each time the product is used.
BioKap Sensitivity Test Tutorial
The skin sensitivity test uses only a small amount of the product, and is recommended to be done at least 48 hours before actual hair dye application. Once the bottles have been opened, if the cream and peroxide are not mixed together, and the two bottles are closed and stored well, they can be used for up to one month after first opening.
