Wednesday, August 19, 2009

Thermofax Basics

The thermofax machine is a relatively simple machine. It features an opening approximately 10" wide (this varies by machine type) into which the thermofax film is inserted. The film is layered face to face with a photocopied design. The photocopy must be created using a carbon toner system. The film/photocopy combination passes through the machine in less than 30 seconds and is exposed to a very hot, bright light inside the machine, which melts the plastic coating of the film onto the carbon toner. When the paper/film sandwich exits the machine and the paper is pulled off, the image transfers to the film and is ready to use. No other method of generating a screen is so immediate.

Believe it or not, thermofax machines are still discovered in the storage warehouses of schools and businesses, because they were discarded when photocopiers were introduced. Older machines are also available through Internet auction houses on a regular basis. New machines can be purchased from Welsh Products and from Guenther Panenka in Munich, Germany. Supplies for the machines are available from Welsh and also from Dick Blick, and for anyone who isn’t interested in purchasing a machine, numerous services exist to generate Thermofax screens from individual designs. (see the sidebar on this blog)

Here’s How it Works:

1. Photocopy original artwork — clip art, black and white drawings, etc. — onto a carbon toner copy. Most commercial copiers use carbon toner systems. Inkjet and other types of computer printers are not carbon toner systems.
Tip: If the copy is NOT a carbon toner copy it will be evident immediately: the copy won’t bond to the Thermofax film when the combination is inserted into the machine.

2. Cut Thermofax film large enough to accommodate the photocopy image and large enough to cover the opening on the plastic frame. The film must extend onto the plastic frame around the opening so it can be properly taped.
Tip: Reduce the photocopy image slightly if it extends too close to the edge
of the opening on the frame. Otherwise, when the film is taped to the plastic frame the outside edges of the design will be lost. It’s a good idea to leave 1" of space around the design so there is room for tape later.

3. Align the plastic film, shiny side facing the photocopy. It seems to work best to put the film on top as the sandwich is run through the machine. The toner design MUST face the shiny side of the Thermofax film. Put the film/copy sandwich inside an acetate carrier or use an 11” x 14” piece of paper as a guide. Fold one end of the paper over about 2” and secure the sandwich at the edge of the paper prior to inserting it into the machine. The carrier keeps the two layers together, and properly aligned.

4. Insert the carrier into the opening in the Thermofax machine. The machine’s roller helps pull the carrier into the machine. The light inside flashes on, and then the carrier exits through a slot at the base of the machine.

5. Open the carrier and remove the copy/ film sandwich. The carbon should be bonded to the plastic surface of the film. Separate the film and photocopy by peeling them apart. Separating the copy from the film pulls the plastic off and opens the design to make printing possible.

6. Tape the Thermofax film to a plastic frame. Use duct tape for permanency. Cut a piece of duct tape the length of one side of the film. Tape the film over the inside opening of the plastic frame. Position the tape so that it passes onto the mesh along the frame edge, which helps keep the squeegee from cutting the film accidentally during printing.

7. Tape all four sides of the film to the plastic frame using the same method. Extend tape over the inner edge of the frame and onto the film about ½" to protect the film during printing. When the screen is taped and the tape cures (approximately 24 hours) the screen is ready to use.

8. After printing wash it gently with a sponge and cool water and the screen should last for hundreds of printings.

A thermofax screen doesn’t have a right or wrong side. The side with plastic film is more fragile than the polyester mesh side, so it might be a good idea to print with the plastic side against the cloth most of the time, but if you need a right and a left version of the design you can clean the screen after printing one side, allow it to dry, and then flip it to print the other side. Just be careful when rinsing, and use a soft sponge instead of a scrub brush.

Film gets old and begins to degrade. On the roll this is indicated if the unused film turns color or gets brittle. On a screen degrading is indicated if the film begins to separate from the mesh before, during or after printing. Degrading can’t be stopped. Cut your losses and make a new screen. Share a roll if you are purchasing a new one. Two people (or four) usually go through a roll of mesh much faster than one person can do.

Carbon toner copies aren’t the only way to make a Thermofax. Carbon pencils and pens work too. Experiment with tools you have on hand, or check an art supply catalogue for carbon based tools.

One of the biggest complaints about Thermofaxes is paint drying in the mesh and ruining the screen. This is frequently operator failure more than it is the paint. Screening goes smoothly if paint is always replenished as the printing proceeds. If the paint being pulled across the screen is fresh from the bottle it will always retain enough moisture to keep the screen open. Too many passes of paint that’s drying out is the main reason screens fail and require re-screening. You can always put paint back, so use slightly more than you think you need. Exception to the rule: dry climates. Add a retarder to the paint to keep it from drying so quickly. (Available from textile paint suppliers.)


    Thermofax Machines, lamps/bulbs and belts.

  2. We also offer custom screen imaging:

    and have reconditioned thermofaxes on our website:

  3. Does anyone have a Panenka machine? I want to buy one for the textiles program at the college where I teach. I am unsure whether I should get a new Panenka or a reconditioned 3M. Any advice would be greatly appreciated.
    Shanna Robinson