Working with perspex

By Emily Watkins

This was my first time making a large-scale work in perspex, so it was a massive learning curve for me.

Hermaphrodite
Hermaphrodite

I had previously made a small version of a perspex piece called Hermaphrodite, a few years ago but had always envisaged it being large. So here I am to tell the tale– welcome to LOOSEgroup’s crash guide to working with perspex.

First things first– drill bits! Plastic has a tendency to crack and shatter so selecting the right drill bit to cut a large hole in the perspex is essential. 

The drill bit choices I had were:

  • a hole cutter (suitable for plastic and metal)
  • a step drill (suitable for plastic and metal)
  • a large gauge wood drill bit.

Out of the three, the circle cutter was the most successful although it did leave some melted plastic around the edge of the hole. It also got a bit clogged up, but more on that later.

The step drill bit gave an uneven and sloped edge. Not good.

The large gauge wood drill bit fared the least well out of the three and caused cracking to the perspex.

The problems I had with the circle cutter (melted plastic around the edge and clogging) were easily solved. Melting of the plastic can be avoided by regular spraying with cold water and bicarbonate of soda. The drill bit can also be un-clogged with the aid of a Bradawl (which is like a spike with a handle).

The drill bits
The drill bits from left to right: circle cutter, step drill, large gauge drill bit

Also, another thing to note is that when drilling holes in perspex, it is important to clamp it to a bit of MDF. Clamping the perspex will stop it vibrating and prevent the sheet shattering.

Once I had finished drilling all of my holes, the next job was to stick my sheets together. To do this I needed:

  • vinyl or latex gloves
  • goggles (to protect my eyes)
  • masking tape to hold the edges in place
  • clamps (optional)
  • glue ( I recommend plastiweld)
  • a fine paintbrush

One of the first problems I ran up against was how to hold the first piece still, whilst glueing the second piece on. To solve this problem I made an L-shaped support in MDF and clamped the perspex sheet onto it using G-clamps.

The MDF L-shape support
The MDF L-shaped support

When I was ready, I peeled back some of the protective sheet and coated one edge of the perspex with plastiweld. This type of glue works by melting the edges of the plastic together, meaning that it will not stick to another surface such as wood or carpet.

I then pressed the next piece of perspex onto the glue and secured it with masking tape, allowing it to dry overnight. Once the first two pieces were together I removed the support and repeated the process using masking tape to hold the pieces together whilst they set.

The perspex clamped to the support
The perspex clamped to the support
Taping the sides together to hold it while the glue sets
Taping the sides together to hold it while the glue sets

Plastiweld takes 24 hours to fully set but it is firmly stuck within a few minutes– so you must work quickly. It helps to lay out everything you need before you start.

A word of warning: I discovered it is best to work vertically. If you lay the piece down horizontally, when you apply the glue it dribbles down on to the surface of the piece, making a mess!

Good luck with your perspex project.

A version of this feature first appeared on http://www.emilywatkinsartist.wordpress.com and is reproduced here with kind permission