Uh, yeah… this is probably a stupid question, but if I iron a surface covered in acrylic paint, will it melt? Which kinds of paint won’t smear, smudge, melt, or otherwise become “wet” if high heat is applied?
You really need to be more specific about how much heat. Most paints will not become wet but they may soften, burn or peel. Without any othe rinfo I suggest trying enamel paint made for automotive header pipes but it all depends on what you are painting.
Applying an iron on its hottest setting to a wooden plank with spray-on acrylic paint. Would that melt it?
Don’t know, but I’d give big odds it would.
Test: fingernail polish is mostly acrylic these days, and you could use some to test–easy, since it dries in minutes.
I’d put a paper towel between the acrylic and the hot iron, though, and be prepared to scrub at the iron with more towel.
Hottest setting on my iron is for linen, next cooler cotton, next cooler wool, next is rayon & polyester, next is nylon & silk, and last and coolest is acetate &, guess what, acrylic.
There are fabric paints that are set with heat. Scroll way down to “Heat-Setting.” I believe they call for lower heat settings – more along the acrylic (go figure) setting than the linen setting.
I seem to remember that tossing clothing that had artists’ acrylics on it in the dryer made it impossible to remove the paint. I don’t know if it’s because the paint melted, but it definitely didn’t come off.
What are you thinking of ironing?
Basic story is that I’m trying to put computer art onto canvases, wood, etc… The surfaces I’m trying to put them on are painted. I read recently that you can iron laser printed pages onto surfaces to transfer them. I’m not sure if this is true; I tried it once, and part of the image indeed transferred, but most of it didn’t.
Summary: I have no idea what I’m doing.
Why not just do a test before trying the actual transfer?
If your laser prints don’t work think about getting some of the commercially available tee shirt transfer sheets that you can print images from your computer. The ones I’ve used worked great. They were for ink-jet, however.
I think paints differ regarding whether there is any kind of crosslinking that happens during or after drying. If there is a polymer in solution to provide a base for the paint, they can add agents that crosslink the long polymer molecules - meaning that various points on one chain will form chemical bonds with neighboring chains. This makes the paint more durable in ways, including no longer being soluble in whatever used to dissolve it, and including not melting (but rather decomposing into smoke and ash at some higher temperature).
They can make this happen by including all the ingredients for crosslinking in the paint, then adding a component that inhibits the crosslinking process. This component would evaporate or otherwise get disarmed once the paint is applied.
I am going to guess that you can test whether the paint will melt by testing whether a solvent like acetone dissolves it. Bear in mind that the crosslinking may take several times longer than the drying does, or maybe even days.
First “Stupid Question” Try it and see for yourself.
Most paints wil smoke, scorch, and char.
Second ?: Flue or smoke pipe paint, stove polish and similar products are made to withstand high temperatures.
Some aluminum based paint/coatings also withstand high temperatures.
polymer chemist checking in: 
[Nit pick] most acrylic polymers do not have a true melting point. They have a “softening point” or Tg (which needs to be above room temperature otherwise they will feel sticky). But for the layman, most acrylics will get very soft on heating, and “appear” to melt. Only highly ordered systems (e.g. crystals) actually melt.
So if your paint is water based acrylic it should work, though heat can damage or change the coloured dyes or pigments, especially in cheaper paints
Oil based paints on the other hands need much higher temperatures to soften as they are highly cross-linked, and so need much higher temperatures (and fierce looking heat guns if you are a repainter) to soften.