Introduction

The incredible, shrinking material! This amazing shrinking plastic is made with specially formulated coatings for use in all color ink-jet printers. Simply print your computer image on the sheet, bake and the sheet will shrink to one-fourth its original size and become nine times thicker!

Materials

Safety Precautions

Wear an oven mitt or insulated gloves when removing the baking pan from the oven. Protect a metal pan or cookie sheet with a piece of aluminum foil to prevent shrink plastic from sticking to the metal. Do not put shrink plastic material on a hot plate or in a microwave oven. Round all corners before shrinking to avoid sharp corners after shrinking. Shrink material is HOT when removed from the oven. Allow to cool before touching. Follow all normal laboratory safety guidelines.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Shrink plastic material may be placed in the regular trash according to Flinn Suggested Disposal Method #26a.

Procedure

Printing

1. Obtain a sheet of printable shrinking material. Print the desired image on the sheet using an ink-jet printer. (Note: Be sure to read all of the tips provided below about printing.) As a control (for later comparison), print a duplicate of the image on a sheet of paper.
2. Use scissors to carefully cut around the printed images, if desired. Round all corners to avoid sharp edges after shrinking and to prevent them from curling and sticking to the sheet.

Baking

3. Preheat oven (or toaster oven) to 350 °F.
4. Use a clean, Teflon-coated baking sheet. Note: A metal pan lined with aluminum foil may be used.
5. Place the shrinking material on the baking sheet and place it in the oven. If the oven has a window and a light, watch as the plastic material shrinks. Describe the behavior of the shrink plastic as it shrinks.
6. Bake for approximately two minutes. Carefully watch the baking process. Once in the oven, within one to two minutes, the shrink plastic material will begin to curl. It will shrink in size and then begin to flatten. Once the plastic is flat, immediately remove the baking sheet from the oven using an oven mitt or insulated gloves. Note: Do not over-bake! Over-baking will dull the colors and cause the edges to become irregular.
7. Allow the material to cool up to five minutes before removing it from the baking sheet and before shrinking another batch.

Analysis

8. Compare the shrink plastic after heating to the control. Did the plastic shrink uniformly in all directions?
9. Compare the reduced shrink plastic to a piece of unused shrink plastic. What differences do you observe?
10. (Optional) Place shrunken shrink plastic on the tray in the oven. Heat at 325 °F for three to five minutes and remove. Wearing insulated gloves, pick up the hot shrink plastic and stretch it. Can you stretch it easily? If the restretched shrink plastic is placed in the oven, does it shrink back to its previous size?

Teacher Tips

• Store shrink plastic sheets in a cool, dry place until use.

• Follow your printer manufacturer’s recommendations to ensure the correct print settings:

  Set “Media” to Coated, Photo Paper or Transparency
  Set “Quality” to Presentation Quality, High Quality or Best
  Set “Mode” to Color Graphics
  Set “Source” to Manual Feed
  Set “Paper Thickness” to the setting used for printing envelopes

• Print one sheet at a time. Do not stack sheets; load one sheet at a time. Refer to the printing instructions for specific loading instructions.
• Your design can be printed on either side of the shrink plastic sheet.
• Print light colors. Colors tend to darken when images shrink.
• Begin by printing small images (¼ of a page or smaller). Print multiple images on each sheet.
• Once you have printed your image, remove the sheet from the printer as printing is completed.
• Do not touch the printed image surface.
• After printing images on shrink plastic material, allow the ink to set for at least 5–10 minutes.
• Once the ink has set, hold the material near the edge to avoid smudges and fingerprints. If desired, carefully cut around the
  printed images.
• Leave a small amount of unprinted material between the printed image and the edge of the shrink plastic material.
• Do not use a microwave oven! For best results, use an electric oven or a toaster oven. A gas oven may not provide even heat and may cause uneven results.
• The printable shrink plastic can also be written on with colored markers.

Discussion

Shrink plastic is made of a bi-axial oriented polystyrene material. Bi-axial means that it shrinks evenly in both directions when heated. This bi-axial oriented polystyrene film has been extruded, or stretched, under stress. Upon heating to 300 °F, the film exhibits what is called a “memory effect,” softening and shrinking to its original pre-stressed size. The material will shrink to one-fourth (¼) its size and will become about nine (9) times thicker, with all dimensions in the same ratio as the unshrunk piece.

Printable shrink plastic is different from traditional shrink plastic in that a special coating is placed on the material so it can first be printed on with a color ink-jet printer and then heated. Without the special coating, bubbles will form on the surface during the heating process and the ink will never dry, making a huge mess. The challenge in developing this product came when trying to apply the special coating without the use of heat (so as to avoid shrinkage), a process called “cold coating.” There was an additional challenge of preventing “delaminating,” or the peeling off of the coating. These problems were solved in 1997 when printable shrink plastic came into existence.