How Long Does A Skin Test Take For Hair Dye?

A skin test is usually done to see if you have any reaction o a product. It is worth doing in some cases especially if you have very damaged hair from using other dye products as a friend recently found to at a hair salon her hair fell out as the salon did not do a test.
She has now paid fro extensions but the salon should be rectifying their mistake as they should have done one to see how her hair reacted to it.
I have also used one product and burnt my head to the point my skin was peeling so yes do one even if it is in a very small spot or you haven't used the product before

Dono i'm a hair dresser but it can take up to 30 minutes to 24 hours to produce the     infection

A patch test should be done 24 hours in advance to having your hair colored.