Well, I found this....
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One of the most popular ways to darken hair is with walnut dye. Be warned, walnut dye will stain flesh quickly, and severely. It is next to impossible to get rid of walnut dye. When dying your hair, if you get the dye on your forehead, face, or neck, you will have to walk around with that for many days before it starts to fade.
With that said, here's a method to naturally darken your hair with walnuts.
Step 1: Obtain some walnuts.
Black walnuts, green walnuts, 'normal' snack walnuts: each has a slightly different shade. Most people say to use black walnuts, but I had an interesting
experience with normal, bought-in-a-bag walnuts. They were shelled, and ready to be eaten. I threw some in a cup of
water and let it sit for 4 days. At the end of the 4 days, the water had turned black with the dye. This is the dye I use. However, for quicker dye, buy a few black walnuts, crack each, and place the entire walnut into some boiling water. Boil for approx. 15 - 25 minutes.
Step 2: Once the water is dark, strain it several times to remove the pieces of walnuts and shells in the water. Be very careful not to spill this water! It will absolute stain every single object it touches, including skin. It cannot be removed from clothing, etc. It will take several days to fade from the skin.
Step 3: Remove as much clothing as you can, or put on old clothing you do not care about. Cover your work area in towels; work over a hard wood/tile/linoleum floor, not over carpet.
If the walnut dye gets on your skin, it will stain. Because nobody wants to walk around with a darkened forehead/face, it is important to avoid getting the dye on your flesh. This is next to impossible. Because of this, I suggest placing masking/paper tape over your forehead. Once you
have placed the tape on your forehead, rub the top of the tape with a liberal amount of
petroleum jelly. This
should cause any dye to hit the tape and roll off, instead of soaking into the tape and staining the skin.
Wear latex gloves. Cover any exposed flesh in a very liberal amount of petroleum jelly. This will cause any way-ward dye to roll off, instead of staining the flesh.
Step 4: Apply dye evenly to the hair. You can either use your fingers to spread it through your hair, or you can use a brush, such as the ones that come with a commercial hair coloring kit.
Step 5: Place a hair cap over hair, and let it rest for about 30 minutes. Longer if necessary, but don't let the hair dry with the dye on it. Be sure to monitor the hair so that it doesn't become too dark.
Step 6: Once the dye has sat for an extended period of time, remove the
shower cap, bend over so that the hair is hanging downwards, and spray/rinse off. Do not just hop into the
shower. The dye will run out of the hair and onto your flesh, staining your skin a darker shade.
Once the dye is rinsed, wash hair with shampoo and blow dry. Once it is dry, you will be able to see the final coloring. If it is not dark enough, repeat above process as often as necessary.
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And I would add..... Have someone assist you

This sounds precarious - LOL
~Jami