Hi all, I have a question I looked for the answer, but found nothing here(probably searched wrong). Anyway, my wife has a project that requires clear epoxy to cover some art, and what she has is super thick. I have heard you can thin epoxy with acetone to make it flow out, but have no idea what kind of ratios to look at. can anyone provide any insight? Thanks in advance.

Pat

I think acetone will work, but denatured alcohol, or low-water content isopropyl alcohol (90% or 99% isopropyl).

You only want to do this if the epoxy is going to be in a thin layer, like paint.  If she wants to encase something in epoxy, she wants to get the stuff that's made for that.  If the layer of epoxy is not thin enough, then solvent is left in the mix and gets trapped, weakening the epoxy.

Note that over time, epoxy glue will yellow in sunlight.  If this is going to be the outer coat, and if the colors are important, then she wants to get something that's specifically meant to be a top coat.

Mr. Maset:

As you can see, we're trying to guess what your wife intends, and giving you advise based on supposition.  Can you say, in detail what her plans are, so that we can give you some useful suggestions?

... My experience is that thinned epoxy comes out gummy and never fully cures correctly....

That is interestingly contrary to my experiences at least when I've used the epoxy as paint, and made sure the film is thin enough to flash off the solvents before the epoxy cures.  But it's absolutely routine for the epoxy left in the paint-pot, that has to try to cure when there's still solvent present.

That is interestingly contrary to my experiences at least when I've used the epoxy as paint, and made sure the film is thin enough to flash off the solvents before the epoxy cures.  But it's absolutely routine for the epoxy left in the paint-pot, that has to try to cure when there's still solvent present.

Thin films behave differently than casting and bonding applications. I wouldn't use an epoxy formulated for painting for bonding nor an epoxy formulated for bonding for casting. Each application has different requirements. Thin films such as painting have a thin enough layer as to allow the solvents to precipitate out of solution. Not so much with a heavy bond or cast scenario and the solvent stays trapped with the mixed resin inhibiting its ability to cure correctly. The manufacturer uses various dopants in the epoxy to facilitate the thickness and quality of the epoxy. Some of these dopants are paraffins which allow the hardening agent and resin molecules to move around in order to properly cure. Think of localized pockets of cured resin separating from the hardening agent. The paraffins help prevent this from occurring and eventually migrate to the surface of the cured epoxy which is why we need a peal ply or to sand the surface of the epoxy before painting.  For making cast parts such as propellers the EPON resins work well while bonding and fiberglass applications West systems works well and of course the two part paint systems and our general purpose epoxies like Bob Smith and Devcon. 

For the application here, there are casting resins specifically made for the shiny table top look which is what the OP is looking for. I'm not specifically familiar with these resins and I'd simply look for a one with a good reputation. The cost of a gallon unit is around $100 and would be enough to do tons of 4" tiles or a large mosaic. What I wouldn't use is West Systems or other epoxy we commonly use for model building. EPON could be used but it would be prohibitively expensive.

How about just apply and use a heat gun to thin it to flow?