No, I do not usually do a strand test, but here are situations where I would:
- I do not know what is on my clients hair, and for various reasons (length, condition, previous color) I need to know how my decolorizer will work as far as even lift I will apply a strand test. I may also question which lightner will work best in this situation, so I may do 2 or 3 strand test. (No, not all lightners are created equal or work the same).
- I would like to know which of 2 or more shades will be appropriate for my desired end result. Example: I have a highly sensitized hair that needs to be lowlighted, which formula will look the best. I might strand test while my color processes at the root to save some time.
This is the I want to change my clients color from color treated black to a much lighter shade and she has and inch of her own Level 5 haircolor, and colortreated Level 3 and wants to be a Level 6 haircolor with little warmth. Here is how to proceed:
- Take a very fine slice of hair in an inconspcious area of the clients head (perhaps nape, but of course assuring that whereever this strand is taken from is a represenation of the what is going on all over the head.
- Mix a small amount of your lightner, color, various colors etc. and apply from roots to end. Allow to process for 20 minutes or so. Wipe strands off very well, and dry. You should have a fairly good represenation of how the lowlight, color, lightner etc is going to work. Now here is where the strand test really comes in handy, when trying to decolorize. In the example above, you want to look at the lightening action that has occured along that strand. If after 20 minutes or so your colortreated level 3 haircolor has not budged, or produced any warmth, or underlying pigement, you SHOULD NOT PROCEED. You are not going to get this hair anywhere near a a level 6 undertones of Orange/yellow.