How to Shrink Silicone

Silicone is a material used in many industries as a liner, seal or protective cover. The material is actually called silicone rubber, one of three types of silicone that also comes in liquid and resin forms. Silicone rubber can be formulated to be heat resistant. These silicone rubbers are used in cooking and manufacturing. However, most silicone rubbers thicken when introduced to high heat, causing a shrinking effect before eventually melting. Fortunately, there is a way to shrink the silicone rubber in mouthpieces, some brands of cellphone covers and other silicone rubber products without melting them.

Things You'll Need

  • Silicone rubber product

  • Deep pot

  • Medium-sized towel

Step 1

Heat water to a rolling boil. You need a rolling boil in a pot that is deep enough to allow the silicone rubber object to submerge without touching the bottom of the pot. Test by placing the object in a cold pot and filling the pot with water until the object is fully submerged. Remove the object before heating.

Step 2

Place the silicone in the water for 10 to 15 seconds to soften. Use the tongs to place the object into the boiling water without splashing. Set a timer to keep the time and avoid melting the silicone rubber. Remove the object using the tongs when the timer sounds.

Step 3

Dry the silicone quickly. Have a towel ready to dry the silicone rubber immediately. Do not use a hair dryer as it could cause melting or further shrinking.

Step 4

Apply the silicone to the object you are working with. Fit the silicone rubber object to the product. Place the mouthpiece in your mouth and bite down for a few seconds; the silicone rubber object will fit to the cell phone, for example, and the mouthpiece will form to the teeth. Allow the silicone to cool on the object to tighten, or set the mouthpiece aside to cool.

Step 5

Repeat until the silicone tightens to the size you require. If the silicone rubber is too loose from the first try, repeat the process until it does fit.


Do not use the hair dryer to melt your silicon rubber product, as it will cause uneven shrinkage and even melting due to direct contact with the heat.

References & Resources