Dyeing an action figure is a great way to give a clean base of color to a piece. It also allows you to have joints whose paint will not rub off with movement and the passage of time. However, it also comes with it's fair share of challenges.
Color - You can't always achieve the color you want because the dye color mixes with the color of the plastic and the paint on the plastic giving you a hybrid color. It is much easier to get the desired color if you start with a white or very light colored piece. Black is usually a safe bet and with enough time, it will work on just about any color plastic.
Rub Off - Dyed parts tend to rub off onto anything they come in contact with, even after rinsing them multiple times. To combat this, after I dye a figure or part, I seal it with a matte clearcoat sealer. You can find cans of this stuff from various companies at just about any hobby store. I personally use the Games Workshop Purity Seal. It's pricey but I like the result.
With those challenges in mind, this is what I use to dye my parts...
It's a small crock pot and a strainer with the handle bent for ease of use and Rit liquid dye.
I add the dye and some water to the pot and then turn it on high to warm up. After fifteen minutes or so, I turn it down to low and add place the parts into the strainer and set them in the dye. I let them sit in the dye for an hour or so, checking on them every ten minutes or so, rotating them to give them an even color and to make sure no air bubles keep dye off the piece. Sometimes more stubborn parts require more time and more heat but for the most part the process happens quickly.
When they've achieved the desired color, I remove the pieces and rinse them with cool water. !WARNING! I always wear gloves and let them dry on several layers of newspaper and paper towels as they will bleed and dye is very hard to remove from anything.
Here is an example of a figure whose body I dyed black.
(More about Cobra De Aco in a future post.)