Q: When you mix your hair color for a predisposition test for an aniline derivative product, do you add the peroxide first or the color?
A: Actually, it does not matter which is added to the mixing bowl first. It would simply depend on your personal preference. Most
stylists add the peroxide developer first because it is the product which must be measured usually. Most hair color formulas come
in 2-ounce bottles that contain enough for application to a single head of hair for all-over coverage. Peroxide developer typically
comes in bulk quantities since the same product could be used with multiple shades and brands of hair color.
The main concern in mixing your aniline derivative color formula for use is to make sure that you
use equal parts of color with developer. An improper color-to-developer ratio is often the key cause of problems with a hair color service.
When doing a predisposition test (also referred to as a skin/patch test) to determine sensitivity
to a color mixture, you should only use a small amount of color and developer, say perhaps a half-teaspoon (2.5 ml) of each. Measure
carefully, mix well, and allow it to sit for five minutes and then apply a small dab behind the ear or on the inside of the elbow and
allow it to sit for at least 30 minutes then wipe it away and wait 24-48 hours to see if there is any reaction of the skin at the test site.
ANY redness or other sign of irritation on a test location is cause to abort any planned chemical
service. Even a minor irritation could be magnified when the exposure covers the entire scalp. Safety is the reason for performing a
predisposition test, and a negative reaction is a sure STOP signal.