Plexiglass is a polymer that is available in sheets and rods. Plexiglass finds uses as a construction material for applications that require transparency. Other trade names for it are Lucite and acrylic. When using this material to form complex items, the attachment of multiple pieces is required. There are many adhesives used with Plexiglass, but the strongest form of attaching two or more pieces is solvent welding. Solvent welding utilizes a chemical that Plexiglass is not inert to. One solvent commonly used is acetone. To seal two pieces of Plexiglass is simple if you follow proper procedures.
Sand and polish the edges of the Plexiglass pieces that you desire to join. Surface roughness will produce a less than satisfactory seal and may cause the joint to leak when placed in contact with water.
Assemble supports to hold the joint together while the solvent evaporates from the weld. The curing time for a solvent weld is approximately three hours.
Pour acetone into the two troughs. Make the level of the acetone between 3 and 5 mm. This will allow the bottom of the two pieces to soak.
Allow the Plexiglass to soak for between 60 and 90 seconds. To determine the exact timing of the soak, perform this procedure using two scrap pieces of Plexiglass prior to welding the actual pieces of interest.
Remove the pieces from the acetone and press them together in the position desired. Wiggle them slightly back and forth and while pressing them together to ensure good contact. Place them in the supports.
Allow them to remain untouched for at least three hours. This gives the solvent time to move back to the surface and evaporate.
Check the piece for trapped air in the joint. Test the joint for leaks when submerged in water. Apply pressure to the joint to determine the strength of the seal.