I've had difficulty painting my FUD models... the issue usually was that the paint wouldn't cure.
Parts were thoroughly cleaned in a variety of ways, using brushing/scrubbing with solvents as strong as lacquer thinner, and/or ultrasonics with strong aqueous cleaners. I'm confident that the parts were free of process wax, oil, water, etc. Yet any solvent based hobby paints and primers would stay gummy on the parts, and just wipe off.
Then I found that water based acrylic hobby paints worked just fine- they dried quickly and hard. Yet sometimes, especially with flat paints, I'd notice a staining of the paint, as if something was leaching out of the plastic into the paint.
But elsewhere I've read that ANY paint, including solvent based enamel, would work on FUD plastic.
So this makes me think- Does FUD need a post-cure under sunlight or a UV lamp? This is standard practice with UV cured SLA parts.. why wouldn't Multi-jet parts also need a post-cure?
So my latest batch of parts spent an hour under a florescent 15W flourescent UV lamp, as well as receiving a thorough cleaning. Just hit a sample part with spray can enamel primer... seems to have dried nicely and quickly, so I'll see how it looks after an overnight drying.
Anyone else having similar issues, and/or trying DIY post cure?