I have the Home Depot egg-crate panels on top of my refugium and some for the top of the tanks. I want to paint the ones for the top of my tanks black. They'll be under metal halides and will definitely be getting saltwater on them.
What's the safest paint, or black color, I can use for this purpose?
I hesitate to say that paint would stick to them but if you want to try I would go with krylon fusion as it is supposed to bond with plastic an a molecular level.
I would be worried about that and the fact that black is going to absorb more heat so they may disform or even melt. I would use the fusion but keep extra crate handy and keep a close eye on it "Just incase".
Good point. One last question...is there some kind of protective high-heat coating I can put on afterwards- sort of like the high heat paint for brake calipers, only a protective coat for plastic?
The only problem is that the heat is comeing from the outside and not the inside. The caliper paint is made to act as hind of a heatsink. to pull heat from it's source and direct it elsewhere, which in your case would be the egg-crate. What lighting are you going to have over this??? Unless you are running high wattage MH I wouldn't be too worried but just keep an eye on things.
I doubt any paint is going to stick for long since egg crate flexes when moved. The flexing will crack the paint and it will begin to flake off. The lighting won't help either. You will likely end up with a mess on your hands. I think I remember there being chromed egg crating available. Check a specialty lighting store or wholesale supplier of light fixtures. You may have to source it from a comercial supplier. The chrome effect might create some interesting lighting effects :idea: Oh yeah, you might want to ask for a chrome or silver gridded light defuser. Most people don't understand the term egg crate and quite frankly I don't get where that term came from either.