So I bought this beautiful flightsuit and jetpack harness from Man Of War. 100% cotton. When I got it, it was snow white.
From research here on the board, it seemed RIT Pearl Gray dye was the way to go. Unfortunately, Pearl gray is much darker than needed, so I did some testing on scrap swatches of white cotton and came up with a recipe.
In 2 cups of very hot water, I dissolved 1 tablespoon of dye powder per gallon of water that I intended to use. I was dying this in a big plastic tub, so I used 4 gallons of water. (4 tbs of dye is less than one package of the dye powder.)
Then I added 1 teaspoon of Speedball Super Black India ink per gallon of water.
I filled the tub with gallons of very cold water. (I DID NOT use hot water. This is cotton. It would shrink.) I tossed in the dye liquid, and added about a cup of salt. Mixed well.
I threw in the flightsuit and stirred constantly for about 10 minutes. Then I hung everything to dry overnight.
When it dried, I ended up with this:
Next, I had to weather it. This was by far the scariest part of this entire process because throughout the weathering, I couldn't tell what the final flightsuit would look like when it was dry. Just had to have faith and use my imagination.
I filled an empty spray bottle with water and about 2 teaspoons of RIT Dark Brown dye powder, and just a pinch of RIT Golden yellow dye powder. Mixed well.
I discovered that the trick to this whole thing was that the flightsuit had to be DAMP so the brown dye would spread out through the fibers and didn't just sit there like paint. The result was supposed to look like old stains that have been washed over and over, but never came out.
I hung the pieces from the ceiling in my garage, and started spraying on the dark brown dye using movie photos as reference. I alternated between the spray bottle and dabbing with a sponge dipped in the dye solution.
I knew that the flightsuit looks much darker when it was wet from the original dye process, so I had to estimate how much weathering to put down. I figured I'd go just a little bit overboard because it would get lighter.
I let everything dry, and it turned out I was right. It got a lot lighter. I went back and added two more layers -- adding additional pinches of dark brown RIT powder to my spray bottle each time to get a darker and darker solution. I repeated the process until I had multiple tones of grime. Some a little more yellow. Some a little more brown.
The final result is this:
And here it is with the white jetpack harness. You can see the contrast.
Here are some close-ups:
Over all, I'm pretty happy with it!