Make Your Own Plexi Welding Cement

Often while working in the shop I undertake some plexiglass (poly methyl methacrylate or PMMA) fabrication of one sort or another.  In many of those instances I need to glue pieces of plexi together.  Well, “glue” is probably not the right word as I found long ago that gluing plexi is a fool’s errand.  “Weld” would certainly be the more correct word, as it involves the melting of plexi on the gluing margins and allowing the liquid surfaces to fuse and form a nearly indestructible bond when it dries.

Plexi welding adhesive is available on the market to accomplish this task, but living in the hinterboonies I had none available for a recent project. Instead I made my own.

I started with a pile of clean plexi shavings from the drill press, then placed them into a glass jar and covered them with methyl ethyl ketone (MEK) a pretty standard hardware store solvent.  Pure dichloro methane (methyene chloride or MC) works even better, but the only MC-based paint remover I had on hand was laced with wax to retard the solvent drying, and in my case, interfere with the solvent action needed for the solvent welding to occur.  So MEK it was.

Next morning I had a nicely viscous solution of MEK solvent with PMMA solute.  I gave it a try on a couple pieces of scrap plexi and let them sit overnight.  The next morning they would not come apart, and when I hit the assemblage with a hammer to test it, it broke but not along the glue line.

There you have it, home made high performance plexi welding solution/adhesive for just a few pennies.