How to Make Plates for Pad Printing

You can make plates for pad printing by exposing them with a homemade exposure unit and a few common supplies found at the hardware store. The pad printing plates most easily processed in-house are of the metal-backed photo-polymer type, available form pad printing suppliers. The plates, also called "clichés," can be handled in normal room light without exposure while being prepped for processing, and are relatively inexpensive. It helps to have a working knowledge of the plate-making and pad printing process, but the plates are inexpensive and forgiving enough to allow room for experimentation.

Things You'll Need

• Laser vellum or film positive
• Photo-polymer pad printing plate
• Clip board, 9 by 12 inches
• Glass pane, 9 x 12 inches
• 4 binder clips, spring type, medium size
• Photo flood lamp or UV florescent tube with fixture
• Digital kitchen timer
• Plastic bowl
• Water
• Paper towels
• Hair dryer

Instructions

1. Obtain a vellum or film positive of your design by printing it out on laser vellum paper (if you own a laser printer), or from a printer's film service bureau. Many screen printing shops have the capability of producing films, but regular printers may not. The vellum must be right reading, toner side down, which can be accomplished by printing the image in reverse. Film must be right reading, emulsion side down. The toner (or emulsion for film) must make positive contact with the plate to avoid light under-cutting.

2. Peel back the clear protective coating on the plate and place the vellum or film positive into position on the plate. Purchase plates that are pre-cut to fit your machine.

3. Place the plate and positive on a clip board (plate metal side down) and cover with a pane of glass. Secure the glass to the clip board with one binder clip on each side. This is your "exposure table."

4. Place the exposure table under the light bulb and fixture, and set the digital kitchen timer for approximately five minutes. The exposure time will vary greatly depending on the amount of UV rays emitted from the bulb.

5. Turn the light and timer on at the same time, shutting the light off when the timer runs out. A timer with an audible alarm will come in handy, and allow you do to other things while the exposure takes place.

6. Fill a plastic bowl with warm tap water, and submerge the plate after removing it from the disassembled exposure table. Don't forget to remove the film from the plate.

7. Rub the plate under water lightly with fingers or a paper towel until the image is visible and the plate no longer feels slippery. You should be able to feel the image engraving by rubbing your finger over the plate. The light hardens the polymer not blocked by the black image on the positive, and leaves the area underneath water soluble.

8. Dry the plate with a hair dryer for about five minutes until all traces of moisture are gone.

9. Place the plate under the exposure light again, without the positive, and post-expose for fifteen to twenty minutes. Post-exposure further hardens the polymer, including the soft areas under the image. The plate is now ready for installation and printing.

Tips & Warnings

• Purchase the best UV bulb you can afford, as it will directly affect exposure time and plate quality. There are a number of low-cost, no frills exposure units on the market which will do a fine job of exposing plates in a minute or two.

• Keep a log of exposure times for each plate, and note the results. Your plate exposure time will vary, and experimentation with longer and shorter times will be necessary.

• Some images may require a halftone screen exposure after the main exposure to increase quality, especially if very bold images and test are used. Halftone screen exposures generally require precise control with a proper exposure unit.

• Make sure that the plates you purchase are "water-rinse" polymer plates. Alcohol or chemical rinse plates will not work with this method.

• Avoid direct sunlight when handling plates and always store plates in a light-tight box or envelope. Sunlight will expose the plates and ruin them.

• Handle plates carefully, as the metal backing can be easily bent, ruining the plate.

• Keep children and pets away from used plate water and follow the plate's material data sheet for safe water disposal.

References

• Silver Clay Art: How to Make Photopolymer Plates
• Ink Cups Now: How to Make Plates
• Pad Print Machinery of Vermont: Selecting the Correct Cliché for Your Pad Printing Job

Resources

• ITW Transtech: Pad Printing 101
• Autotran: How Pad Printing Works