My mom and my aunt used to dye their eyebrows with hair dye. Pretty funny to watch two old ladies temporarily turn themselves into Groucho Marx. Mom always complained that she had to buy a whole box of hair color each time they wanted to dye their brows. Thinking about this recently, I started wondering why hair color doesn’t just come pre-mixed in a bottle. In case you’ve never colored your hair…a hair color kit invariably contains a bottle of hair color and a tube of developer you mix with the color. Instructions always tell you to use the mixture within a short time, like an hour.
Clothing dye comes ready to go, and if you wanted to, you could use a little clothing dye now and save the rest for later. Why doesn’t hair dye work this way?
The direct dyes normally sold premixed are (a) not as good as other dyes, and (b) not at all substantive to hair. They often require more heat than people can tolerate. Hair coloring begins with chemicals than lighten the hair and open the hair shaft*, and the dyes are carefully selected to respond in this environment. They are usually reduced by the presence of a base (ammonia or a derivative), and penetrate the hair shaft in this form, and subsequent oxidation will cause dyes to “set” – the hair shaft closing up at the end, as well.
Thanks, Nametag. So all this can only happen if the ammonia is combined with the hair color just before use? There’s no way to combine them at the factory and no way to stabilize them?
Well, there is, but then you’d have to heat your hair (and presumably your attached head) to 140 degrees or more, for 10 minutes at least. I’m not sure there’s much of a market for that.
Clothing dyes are designed to be applied to fabrics and then set by heat - hair dye has to rely on chemical reactions to accomplish the same task. There’s a limit to how long those chemical reactions will last, which is why the mixing is necessary. It’s like asking why they can’t make Coke that will stay fizzy for weeks after it’s been opened. Chemical reactions don’t work that way.
If you really don’t want to waste a whole box of dye, if you look at the included directions (that paper that the gloves are wrapped in ) you’ll see a paragraph about doing an allergy test - that set of directions tells you what proportions to mix a smaller amount of dye to test on your skin. I can’t tell you that you can use that amount on your eyebrows, because it might get into your eyes, but I can say that the amount is about right if someone were to consider it.
Now the real question should be, “Why aren’t there smaller boxes of dye marketed for eyebrows and … um… other places, so that all of the drapery matches.”
Short answer to that question: No reputable hair-dye company can market ammonia dyes which are intended for use on the eyebrows, because as soon as one person gets it in their eyes, the lawsuit would cripple the company.
As for the other dyes, there’s actually a company that markets them now - it’s supposedly formulated specifically for the coarser and darker hair down there. If you Google the search phrase I’m sure you’re thinking of, it’ll be one of the first results.
Mom always complained that she had to buy a whole box of hair color each time they wanted to dye their brows. Thinking about this recently, I started wondering why hair color doesn’t just come pre-mixed in a bottle. In case you’ve never colored your hair…a hair color kit invariably contains a bottle of hair color and a tube of developer you mix with the color. Instructions always tell you to use the mixture within a short time, like an hour.
) you’ll see a paragraph about doing an allergy test - that set of directions tells you what proportions to mix a smaller amount of dye to test on your skin. I can’t tell you that you can use that amount on your eyebrows, because it might get into your eyes, but I can say that the amount is about right if someone were to consider it. 
