Those were the materials I used. I already had oil paints and OMS (Gamsol specifically) on hand, and I bought some GE silicone 1 from the hardware store and got to painting.
I have some more elaborate painting schemes in mind for future characters, but I thought I would start out with something simple. Like nipples!
First you need to clean the area you want to paint on thoroughly with soap and water. After doing that you might want to wipe some acetone or solvent on the spot in order to remove any lingering grease or dust. Depending on how much silicone you use in your painting mixture, the result will probably end up a little shiny. I worked around this by having my final layer of paint use a little more oil than silicone, so it decreased the shininess somewhat. Once I added baby powder to the figure everything seemed to blend together in terms of glossiness. The particular brand of silicone I used dries very quickly- you only have a few minutes to paint an area of the figure before it starts becoming tacky, which would make painting a large area of the figure rather difficult. If you mess up and area you can just wipe the paint off with solvent.
Since there isn't really any way for me to post the images here and still be able to see the actual work, you'll have to click on the links below.
This is a darker skinned body that I had dyed earlier. I'm still working on making matching hands/feet and painting a custom head.
I originally was looking into silicone paints because I wanted to know whether or not it would be an effective method of painting an entire phicen figure a darker color. While that's probably possible, my little experiment here leads me to think that would be really difficult to do without an airbrush to lay down the color, even then it would be hard to paint since you'd have to spray evenly on all of the various contours and crevices of the body. I think this method of painting is good for smaller details- I'm thinking about making a freckled body at some point in the future.
I would describe the silicone paint, once it has dried, to be "functionally" permanent. It doesn't come off with soap and water, and doesn't stain other fabrics. I say functionally because if you rub or scratch the material pretty hard, it will start to peel off, and if you take a cloth and soak it with solvent you'll weaken and dissolve the silicone. But otherwise, regular handling shouldn't remove the paint from the surface. I actually prefer this over being completely permanent because I can change things at a later date if I want to, which isn't uncommon for me because I like to nitpick things. Also, the permanency of color of the paint will depend on how much silicone you use in your mixture relative to the oil paint. If you use mostly oil paint and a little silicone, soap and water will make the color fade somewhat. So basically don't rub or scratch the area really hard.
I've never used actual artist's grade silicone paint before, so I can't say what the difference is between this method and using ready-made silicone paints. I imagine the professional paints lay down on the figure more evenly, and probably don't dry quite as quickly. Once they do dry they're probably more permanent as well. But if you aren't interested in spending money on professional silicone paints, or just want to paint something simple, this seems to be an effective method.