Thermoform

To create thermoform images a sheet of plastic (often Brailon) is heated until it is soft, and sucked down over a 3D collage master (a sort of reverse mould) to produce a positive 3D image. Thermoform graphics are also known as Vacuum forming and current brands include C.R.Clarke, Brailon

How to Make Thermoform Tactile Graphics

The key to a good thermoform tactile graphic is a good master. The base of a thermoform graphic master is made from a thin porous card the same size as your Brailon sheet.

By marking out the lines and areas of your design onto the base you are then able to build up your master using common materials such as thin iron wire or string for lines, and balsa wood and card for larger, higher areas. Some designers use ceramic tile cement, which although brittle when set, is easy to shape into detailed forms.

Techniques

There are four variables to consider when thermoforming:

1. The weight (thickness) of the plastic
2. The temperature of the heating element
3. The length of time the diagram is held under the heat
4. The time the vacuum pump is on

The balance between these variables is critical, and settings vary between machines. Refer to the manufacturer's guidelines and experiment with different settings for your set-up. Start with a medium temperature and short times and increase or decrease as necessary.

Brailon plastic sheets are designed to be thermoformed with the smooth side touching the master, and the slightly bobbled side up.

If a master has a thick base, or is built up over many levels, you may need to drill small holes through to allow the vacuum to be developed around the master.

Masters can start to degrade when used to produce many copies in one go. Allowing the master to cool a little after 10-15 copies can help to prolong its life.

Advantages

• Good height and texture variations are possible
• It is easy to produce multiple copies from one master
• Pages are durable and wipe-clean
• Braille text is easy to make
• Copies are cheap to make

Disadvantages

• Making masters is labour-intensive and requires craft skills
• Masters are fragile and have storage and repair issues
• Vacuum forming machines are expensive, costing several thousand pounds
• The size of pages is limited to 11" x 11.5" (21.5cm x 28cm) on non-industrial machines
• The speed of reproduction is slow
• The images are single colour and can be difficult to see

Top Tip

• Do not use rubber-based glue or any item likely to melt from the heat of thermoforming.

Where to buy materials and equipment

Vacuum forming machines:

• C.R.Clarke

Brailon plastic sheets:

• RNIB
• American Thermoform Corporation