Plexiglass glue is the substance you need for joining two pieces of plexiglass. Although you can see through it, plexiglass isn’t glass at all, but a plastic polymer, or acrylic. Using plexiglass glue is a delicate business as it’s all to easy to end up with glue smeared on the plexiglass itself.
1 - Sanding
You need to make sure you sand the areas of the plexiglass where you’ll be using plexiglass glue. By coarsening the surface this way you allow the glue to bond better. Be very careful when sanding, as you only want to sand the glue areas and not leave scratches anywhere else. You will also need to sand the edges if you’re applying glue there.
Use a fine grit of sandpaper. That will allow you to roughen the surface without scratching too much. Be sure to clear all the grit from the plexiglass after sanding. Use a tack cloth or wash the plexiglass, allowing it to dry completely before using the glue.
2 - Clamps
It’s important to position the plexiglass properly before applying plexiglass glue. When joining at the edges, stand the two pieces and 90 degrees to each other. Use C clamps and metal strips to have the plexiglass in position, making sure there’s a gap between them. This makes it easier for you to apply the glue without worrying about the plexiglass moving out of position.
3 - Applying the Glue
The real trick comes with the application of glue. You have to be extremely careful to only use a thin bead so it doesn’t go elsewhere on the plexiglass. You only need to apply the glue to one of the surfaces to be joined. Use silicone glue for the best results. The bead of glue should only be about half as wide as the area to be joined. This will minimize the glue that oozes out as you join the pieces.
4 - Removing Glue
It’s almost inevitable that some of the glue will ooze out from the join. Use a rubber trowel to remove as much as you can, being careful not to smear it. After the glue has dried you can remove any excess by dipping a paper towel in acetone and rubbing it over the area until the plexiglass glue has gone.
5 - Drying
To ensure a good join, after you’ve applied the plexiglass glue you should loosen the clamps and push the two pieces together. Once they’ve been securely joined, tighten the clamps again to keep the pieces properly in place. You’ll need to leave the clamps in place for 12 hours to give ample time for the glue to dry.
6 - Type Of Glue
It’s important to select the right kind of plexiglass glue. Avoid anything with solvents as this will simply melt the plexiglass. The glue also needs to look transparent after the join has dried. There are several products on the market that will do this. Shop around, paying attention to the ingredients. If you’re not sure which is the best product, ask the hardware store; they’ll be able to give you good advice.