About 30 years ago I made my own with a mixture or rubber cement, rubber cement thinner and oil paint. I mixed it thin enough to pass through an airbrush. You can also use it as a thin wash or stain to bring out fine details. A roughly torn sponge dipped in this mixture can be used as a stipple, similar to make-up stippling.
It's flammable and you probably should find a better alternative. If you do try it, wear a respirator and use it out doors.
I use fw inks, they are water proof and thin with alcohol.Daler-Rowney FW Acrylic Water-Resistant Artists Ink - BLICK art materials
Not to vear too far off the subject, but can anyone tell me (and others) what they use to clean or just to protect a new rubber (dark knight) mask?