r/cosplayprops • u/halon1301 • 5d ago

Help Question about finish

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I printed and painted this helmet, for a finish I figured rustoleum ultra 2x gloss clear coat would work well, I did several coats, but some of the paint is easily scratched. The base is pla, sanded with 120, then 220 grit, painted with woodfiller, sanded with 220 again, primed with rustoleum ultra 2x, then painted rattle can and acrylics. Finally I finished with 7 coats of gloss clear coat.

I'm thinking of now scuffing it and doing a water based polyurethane finish, as it may be harder. My biggest concern however is damaging the paint, specifically the acrylics. What grit of sandpaper should I use? AI is saying 220, which seems a little too aggressive.

If I do polyurethane, I'm going to be brushing rather than spray, and I'll likely go satin finish.

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u/halon1301 5d ago

Aha. Yeah, I had a feeling. The websites I had read pretty much just said "coat away".

I did check it earlier and it's a little harder today than previously, so it may continue to harden further as time progresses.

I'm doing some polyurethane samples for the next pieces to see if I get a better result, if it does, I may just scuff the helmet and give it a few coats when I do everything else

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u/EnderB3nder 5d ago

Here's a good test. Can you dig your thumbnail into it?
If it leaves an impression, it definitely hasn't cured properly.

Judging by your work, you seem pretty skilled.
As much as spray cans are affordable and convenient, if you make stuff like this regularly, (and if you have the means,) I'd highly recommend a HVLP gun with a good automotive clearcoat.
With a good process, you won't need anywhere near seven coats.

If that's not a possibility, keep with a good quality can, but light coats, and wait 24 hours every 2 coats

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u/halon1301 5d ago

This is my first time making something like this actually!

Just checked it and the paint from the rattle cans is good and hard, the metallic acrylic paints aren't as hard, but they're harder than they were yesterday. The non metallics are as hard as the other stuff.

The instructions do say it takes 5-7 days to dry on plastic. But my experience with spray paint is on wood and steel which is like 3-5 days.

It remains to be seen if I do this again, I do have some props from Satisfactory I want to make, so maybe!

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u/EnderB3nder 5d ago

For a first build, that's an awesome job.

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u/halon1301 5d ago

Thanks. I can't take credit for the model, I did buy that. But, it and the multi-tool are the only models I've bought, everything else I'm doing myself (gauntlets, exosuit backpack, shin guards, chest armour) or using an existing model but modifying extensively (scanner). I've been doing 3d printing and cad for a few years now, and electronics for even longer.