Two minutes at the desk, a day before. We get asked to skip it every week and the answer is always no.
A patch test is a dot of the colour we are going to use, put behind your ear or inside your elbow, left alone for a day. If nothing happens, we colour your hair. If the skin goes red, itches or swells, we do not, and you have found that out on a coin sized patch instead of on your scalp.
We get asked to skip it most weeks, almost always by somebody who has coloured their hair for years. That is exactly the person it is for. A reaction to hair colour can arrive suddenly in somebody who has had none before, and it is not something a stylist can predict by looking at your hair.
It costs nothing and takes two minutes at the desk. Come in when you are passing, or come the afternoon before. If you are booking colour through the form, the confirmation email tells you to come in for it and we will ring if you have not.
One salon down the road offers to do it at the same appointment, which is the same as not doing it at all. If somebody offers you that, they have told you something useful about the rest of their work.