How to Shrink Rubber

Co-authored by wikiHow Staff

Rubber is a common elastic substance, used everywhere from gloves to gaskets. Like an old T-shirt that has seen many runs through the dryer, rubber shrinks when exposed to heat. You can easily shrink rubber using hot water or by blowing hot air onto it. Soon enough, you will be able to shrink a rubber glove to fit your hand or fit a gasket into a tight spot with ease.

Method 1

Method 1 of 2:

Shrinking Rubber Using Hot Water

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Run hot water over the rubber. At first, try using tap water. If the rubber is weak enough, the water will eventually force the rubber to contract and shrink.^{[1]
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- If the hot tap water has no effect, boiling the rubber may be more effective.
2
Place the rubber in boiling water if hot tap water fails to shrink the rubber. The high heat will force the rubber to shrink if you allow it to boil for 5 to 10 minutes.^{[2]
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- In some cases, boiling will return the rubber object to the desired size and shape just by removing any dirt and debris that has collected. If the water is dirty after the rubber is removed, this is likely the case.
- The boiling point of rubber is much higher than the boiling point of water, but take care that the rubber is not damaged by looking for signs of wear, such as spots melting away or debris floating to the surface.^{[3]
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Bend the rubber into shape. If there is a specific shape that the rubber must fit, you can try reshaping it before it cools.^{[4]
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- Be sure that the rubber has cooled enough to be handled, but not so much that it is fully rigid. Gloves may be helpful for this task.

Method 2

Method 2 of 2:

Using a Blow Dryer to Shrink Rubber

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Place the rubber object on a heat-proof surface. Whether you put it on a plate or a piece of bakeware, make sure that you will not have to make contact with the rubber while you are heating it up.
- Wearing eye protection and a dust mask will ensure that you are not harmed by the heat or the possibility of smelly fumes. While it is just a blow dryer and the risk is low, taking precautions is never a bad idea.
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Set the blow dryer to the highest heat setting. You will want to be sure that you are shrinking the rubber effectively. ^{[5]
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Blow hot air on the rubber. Try to be as uniform as possible, spreading the heat around evenly so that it can fully penetrate the rubber and shrink it equally all around. Apply heat for around 5 minutes, going for longer if necessary. ^{[6]
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- The rubber may begin to emit a slight smell. While it is highly unlikely, check that you are not burning the rubber by looking for signs of damage or darkening.
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Allow the rubber object to fully cool before handling. The heat required to shrink rubber could hurt you, so it is best to handle it with gloves or wait for it to cool down.

Warnings

If you plan to use the blow dryer method, consider using protection, such as goggles, gloves, and dust masks to ensure your safety.

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