Strand and Patch Testing
It's a good idea to do a strand and a patch test before you color your hair, even with natural dyes. A patch test is to make sure you don’t have any allergies to the mix with a small exposure before going all out. A strand test is to check on the color before you commit in a big way.
Due to differences in water, hair care products, individual body chemistry and other variables, the results of a natural dye mix are going to be different from one person to the next. It's highly recommend to do a strand test before coloring your hair to ensure you get the results you expect.
The first step is to harvest hairs from your brush or last trim. Then you need to mix a tiny batch of the recipe you plan to use, exactly the way you intend to do it for the real thing, just small. The key here is to keep the ratio of the powders the same. For example, if you plan to use an Ancient Sunrise ™ Henna for Hair Kit: Dark Brunette, you’ll notice that it comes with 100 g henna and 200 g indigo. That’s a 1:2 ratio. Your strand test mix should be the same. You could use 1 teaspoon of henna and 2 teaspoons of indigo. You don’t have to buy extra dyes for this. The tiny amount that is needed won’t be missed if you just scoop it right out of the powders that you plan to use for your full treatment. If you don’t want to buy a lot of supplies before you’ve done your strand tests, you can get $1 samples from Mehandi.com that are just the right size for strand and patch tests.
You’ll want to use exactly the same procedure that you plan to use for your full head of hair. That means you should use the same liquid for your henna, let it stand for the same time, and at about the same temperature. When the mix is prepared, put it in a sandwich bag or a bit of plastic wrap and wait the same amount of time you plan to use when you do the real thing. Let it stand in a warm place to simulate body heat (a pocket works well for this, or under a desk lamp). After you rinse your test hair, let it stand for a few days to let the new color oxidize a bit so you can see the final result. If you like the color you’re ready, if not tweak the recipe and strand test again.
Even though plant dyes are much nicer to your body than bottled dyes, it's a good idea, especially for those with sensitive skin, to do a patch test to check for allergies first. The most efficient way to do a patch test is to put a small dollop of the paste you use for your strand test on your skin for several hours and watch it for about two days. The inside of the elbow or wrist is a good place to patch test. This is an area where skin is most sensitive and an area where you can see the results easily. If it becomes itchy, bumpy or discolored (keeping in mind that good henna should color your skin orange and such a result is not an indicator of allergy) then you may be allergic to something in the mix. It would be a good idea then to patch test each ingredient individually to see which is causing you the problem. Remember that the liquid that you use for your mix could be the culprit too! Many people are sensitive to citrus and will get red, itchy or welted from prolonged contact. If you see this kind of reaction try mixing some henna with tea and see if you get the same result.
Once you’ve gotten results you like from a strand test, and you’ve done a patch test with no discomfort, then you’re ready to color your hair!