I’ve been using grey resin for a while now, and quite like the resilience I get when the parts are still green. I realise, though, that they will slowly cure with the UV in normal light. I’m guessing that painting the parts will prevent, or at least slow, the curing. Has anyone any thought on what could be the best coatings that will prevent the UV curing? And would it be possible to do a partial cure so that some parts of a model were fully cured and others were left green?
Without the outside cured, I don’t think that any type of coating would adhere.
I would make sure the outside surface is absolutely clean before coating. I think you have a lot of options in terms of UV protective coatings. As for which one would be best probably depends a lot on exactly what you are doing with your part. Is it going to be outside? Inside? Is it going to be actively used (experiencing friction and surface contact regularly)?
I’m not sure what kind of luck you could expect from partial curing. You could try masking off an area while you cure. With a standard resin I’m not sure I’d bother - they should do just fine without post cure.
Why ? When properly cleaned, the surface of standard resin parts is quite clean and I don’t see why a coating would adhere less than on a cured part.
@billb : there are quite a lot of acrylic based clear coating that are UV resistant :
Even if it’s not indicated on the bottle, acrylic has a high absorption in the ~400nm range and will work well at preventing or slowing the curing of the part.
I don’t know for sure if it would work, but I would expect that coatings would have trouble drying properly on a surface like that.
Also, over time it could start leaking resin
I think you misunderstand what I am trying to do. Imaging two parallel plates joined together by a rod. I want the plates to be able to twist relative to each other so that the rod acts as a torsion bar. For this simple example I could print the whole part and then mask the rod with, say aluminium foil, before curing the part under UV. This would make the two plates fully cured, and hard, and the rod would still be green, and relatively soft, allowing it to act as a torsion bar.\
Except what I’m actually making is a whole lot more complicated:-
I maintain that acrylic spray paint will have absolutely no issue adhering to green resin. Out of the printer the polymerisation isn’t 100% complete but the part is already “solid” and there will not be any liquid resin “leaking” even after a while, that is if the parts have been properly cleaned with IPA. Formlabs even recommends to not post-cure standard resins for certain applications.
UV resistant coatings are made for exactly that : preventing UV exposure on sensitive surfaces. You might even already have some as when painting scenery and characters you may use a clear protective coating to protect the paint… odds are this is an acrylic paint.