For shrink plastic pieces that are to be used in making jewelry, artists generally use a 1/8-inch punch, which results in a 1/16-inch hole. That’s perfect for most jump rings.

Notice, though, that the distance from the edge of the piece will also shrink proportionately. Be sure to punch any holes far enough from the edge to allow for wide enough margin after shrinking. The plastic is fairly strong, but it can break or tear on under stress if the margin between the hole and the edge is too narrow.

When shrinking plastic cups or other industrial (not artist-grade) shrink plastic, you may need to experiment to get holes that are the size and shape you want. As I mentioned in my last post, the plastic from the cups, especially, shrinks drastically in one direction but hardly at all in the other.

You may need to improvise. For example, you may have to punch long, narrow, lengthwise holes before shrinking in order to end up with more or less round holes after shrinking.

The same principles apply to assemblage, though you may want bigger holes.

Luckily hole punches are made in all kinds of sizes and shapes nowadays. We’ll talk more about those another time.

Someone accidentally shrinking the clear top of a delicatessen container is said to have led to the invention of shrink plastic as a toy. That led to the popular product, Shrinky Dinks. Shrink plastic as an art medium was later discovered by artists.

Artist-Quality Shrink Plastic

Artist-quality shrink plastic, such as that sold by Lucky Squirrel, is wonderful. it is easy to use and shrinks uniformly. Be sure to visit the Lucky Squirrel web site and view their gallery to see the many fabulous things you can make with true, artist-quality shrink plastic.

Artist-quality shrink plastic is far advanced from the children’s toy shrink-plastic kits many of us played with as children. I love using it to make jewelry and other projects.

However, artist-quality shrink plastic can be expensive, and it comes in a limited number of colors. Shrink plastic sheets come in practical, versatile colors such as black, brown, opaque white, clear, and frosted. Still they are limited colors, and it is fun to experiment with shrink plastic from other sources.

Shrink Plastic from Unusual Sources

For art fun cheap, we like to find, salvage, and experiment with the commercial shrink plastics that you can often get for free. The more you look around, the more you will find examples of heavy shrink plastic that is used commercially and then discarded. Often you can save the plastic, decorate it, and reshrink it.

You can find many products, sometimes for free, that are actually made of or packed in shrinkable plastic. Always check the recycle mark on plastic containers. (Remember the deli container lid that started it all.)

Check the plastic containers in your pantry and at the grocery store, especially picnic supplies. If the number in the center of the mark is a 6 (in the U.S., at least), you should be able to safely shrink it with a heat gun or in an oven.

The mark in the picture below is a 5. That means it is not shrink plastic, so don’t heat it!

How to Shrink Plastic

To safely and evenly shrink plastic, you can use your kitchen oven. Put the pieces on a cookie sheet lined with aluminum foil. The smoother the surface, the more evenly the plastic will shrink; so place the foil shiny side up.

Or you can use the kind of heat gun that rubberstampers and other hobbyists use to activate embossing powder. Those are just the right temperature. You can buy them in hobby stores such as Michael’s and Hobby Lobby, and sometimes other places. The price ranges from about $10 to $20 in the U.S.

Caution: Always be careful. Work in a well-ventilated area. Do not overheat. If you smell anything, if your eyes water, or if you notice anything odd, stop. Never try to shrink any plastic you can’t identify. Even fumes you can’t smell could cause long-term damage. Never heat Styrofoam!

Clear Shrink Plastic

As mentioned earlier, the tops of many deli containers are Type 6 plastic, which you can use as shrink plastic. So are some of the large, clear clamshell containers that deli sandwiches come in.

Most embossed features, like the recycle mark and any borders, will shrink out, so experiment and see what you can do. After all, it’s free.

Some clear drink cups sold in grocery stores are also shrinkable plastic. After a party or picnic, you can wash them and use them for shrink plastic.

However, because of the way they are stretched into cup shape, they will shrink drastically in the vertical direction and only a little horizontally. If you plan ahead, you can use that as a special effect, but don’t plan on using the cups as you would regular, flat shrink plastic.

Stained Glass Colors

Many stores sell Type 6 plastic cups in transparent colors: pink and blue all year ‘round, and red and green around Christmas.

It is worth figuring out how to deal with the uneven way the cups shrink, because their deep, rich, stained-glass-like colors make wonderful embellishments for paper arts or beads for jewelry-making. They can be used in assemblages or attached to canvas in acrylic paintings.

I recently found a package gorgeous purple shrinkable cups at a dollar store. They also had other colors, such as blue and green. Always check the Recycle mark, however, before shrinking.

Solid Colors

Solid color cups made of Type 6 (shrinkable) plastic are sold in many grocery, drug, and discount stores. I haven’t tried the solids yet, but they are basically painted opaque white shrink plastic, so they should work.

Preparing Cups for Shrinking

Here is how I prepare shrinkable plastic cups for shrinking into a flower shape:

1. Use kitchen shears or other strong scissors to cut the cups vertically from top to bottom.

2. Cut the ends into a rounded shape, cutting off the rolled edge. They should then look like this:

3. Be sure to trim off any splinters, such as the one shown in the picture below.

While soft and harmless when cut, they can be hard and sharp after shrinking. It is best to get rid of any sharp points before you shrink.

4. For some purposes, such as assemblage, you may want to punch one or more holes in the round center, which was the bottom of the cup, or in one or more of the “petals.” I recommend using a strong, cheap 1/4-inch metal hole punch. It will take some strength.

Note: To sharpen the punch, use it to punch holes in aluminum foil first.

4. Use a heat gum carefully. Do not get it too close to the shrink plastic or any other plastic surface, such as carpet, that can melt. (Ask me how I know this!)

Note: If you have some metal kitchen tongs or insulated tweezers from a tool kit, it’s easier to hold the plastic without burning yourself. Or you can shrink it on a cookie sheet (covered with a sheet of aluminum foil) in the kitchen oven.

Here is a scan of some cups that I shrank hurriedly to illustrate this post. I have had better results in the past.

My current scanner has a very shallow depth of field, so only the parts of each cup that actually touched the glass scanner bed are in focus. Still, you can see the effect.

When you shrink cups in the oven, the shapes should shrink very flat. Remember, that you can always reheat and reshape shrink plastic even after it has been shrunk.

5. Some artists use wooden spheres, wooden eggs, and other shapes from hobby stores to shape the heated plastic. You can also use a block of wood to flatten shapes while they are hot.

Note: The purple cup turned out to be Recycle 5, but I tried shrinking it anyway. It did not so much shrink, as shrivel. But I think it is interesting and could be used in a mixed-media painting or an assemblage. I would NOT recommend heating any plastic that is not labled Recycle 6, however, especially in your cooking oven. Who knows what toxic gases I released by shrinking that cup?

Making Shrink-Plastic Leaves

One of the amusing things about shrinking plastic cups is how much they shrink vertically. Instead of cutting petal shapes, you can cut out long slender leaves (like willow leaves), running from top to bottom of the sides of the cup. When you shrink them, they become round, fat leaves, because they shrink only in length.

Have Fun Shrinking Plastic…and Let Us Know What You Discover

I’m sure you can make many other shapes as well. Please come back and tell us what you did. If you post your creations somewhere on line, leave us a link, and we’ll go see them.