Spray primer finally bit me this time. I lost about five 3D-printed miniatures to the primer, which refused to cure past the “sticky” phase, even after waiting about two weeks. Only after putting them outdoors in the Florida heat did they make any progress, but by then it was too late. Thankfully all I lost was time since they were printed minis and not retail.
This happened because last week I decided to 3D print a One Page Rules Dwarf Guilds squad to proxy Votann for Kill Team. I have a Kasrkin team and I decided I wanted to make this second squad so I could try to play a few test games against myself before I went to the store and tried some PUGs. Then, also, if I needed it it’d be there for me to use in case my opposition was running Kasrkin and I needed something else until I can afford a Votann box of my own.
So I used my Flat Gray Rustoleum and put some on about five of the 10 minis and let them sit. And sit. And sit.
I already primed my GW Kasrkin models with Flat Black Rustoleum and had glorious results with it. But for some reason I bought black resin this time, and when I go to prime miniatures in black I have to use a lighter-colored primer so I can ensure I don’t go over spots that are already done more than once. So I used my Flat Gray Rustoleum and put some on about five of the 10 minis and let them sit. And sit. And sit.
And they never went past the curing phase.
This phase is pretty crap because it means that the miniature will be sticky to the touch while the paint cures to the miniature, making it feel like your put your hands on a spoon with maple syrup or something on it. You can’t really paint it when it’s like this, because if it does dry all your acrylic layers will crackle and fall off eventually.
I discarded most of the miniatures out of frustration and re-printed new ones. But I realized that most miniatures are more precious than this and can’t be so easily replaced, so I opted to teach myself how to fix this. So after digging the minis back out of the garbage, I’ve come up with two solutions.
Option 1: Heat
The first is to let it sit in the heat, as I mentioned, where local outdoor temperatures were about 90 F/33 C. (You can apparently just use a hair dryer to achieve a similar result.) After about a day outside the paint finally stopped being sticky, but much of it fell cracked and fell off, too. I think it never really took properly and thus the never-completed curing phase.
I think I could’ve just re-primed the miniatures if I wanted to here. The new layer of paint should have mixed well with the old and prevented issues. But they had been damaged because I had thrown them away twice already and so I opted to just move on.
Option 2: High-percentage isopropyl alcohol
I’ve done this before. You soak the miniature in the rubbing alcohol for a few hours and then scrub it with detergent and a toothbrush. This will get off most of the primer and give you room to re-prime again.
Risks here are isopropyl can eat plastic kinda bad, particularly polystyrene. Polystyrene is the plastic that a lot of miniatures are made out of (generally stuff from sprues). I find this fairly restrictive, though if you want to just remove the primer it may be the only way to go. I’ve found that the really determined will use this when stripping models they bought second hand to ensure they have greater control over it.
DO NOT USE THIS FOR VERY LONG. Because your miniature will melt a little, this can remove your details (the FACE, logos, edges, etc.) and eventually melt your mini entirely. So one or two hours at a time is best according to what I’ve read online.
Option 3: Standard citric-acid-based cleaners (Simple Green, LA’s Totally Awesome)
Why not use common solutions like Simple Green and LA’s Totally Awesome, which are citric-acid based cleaners and will strip acrylic paint like water once given enough time and not eat through most kinds of plastic? Hardware rattlecan primers, like Rustoleum and Krylon, are oil-based and use etching chemicals like acetone to dig into the plastic. Once cured they essentially become immune to these chemicals completely.
You can try, but it’s unlikely you’ll get enough of it off to genuinely say they’re resolved. But at that point you might have enough of the un-cured primer off the model and maybe you can prime in other ways. Since this isn’t a real result, I don’t consider this a true option for this problem.
Summing Up
Ultimately the best result is just to try heat. If after a day your minis still haven’t cured, set them in the summer sun or hold a hot hair dryer next to them for a little bit. This should either cause the uncured paint to dry or, if nothing else, fall off so you can scrub it and re-prime it.
If you want to just start over, you either may be out of luck or need to risk the isopropyl alcohol stage. But if you do, only use it for a few hours. After that you’re going to really risk melting your miniature and turning it into a blog of goo, or a featureless mess. (This risk goes out the window on other types of plastic, obviously.)
I would say that, barring huge batch primes, if you have another option to go for it. A successful hardware primer is going to be wonderful, but a failure is pretty catastrophic. The difference you get between a hardware primer vs. a miniature primer or airbrush primer is so small that it isn’t really worth taking the chance.
I will note I’ve never been failed by black hardware primer. I think this has to do with the way lighter colored primers (particularly white) have to be formulated to get them to work in a rattlecan. So I’m less wary of this option than the others. That said, I’m done taking chances and I have the luxury to use something else.
And with local weather getting extra humid, rattlecan is becoming riskier by the day. As such, I think I’ll just keep airbrushing, even for my batch primes. Once things start drying out again I’ll take another look at my old friend, the hardware rattlecan primer.
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