Silicone Rubber Care & Maintenance

The silicone rubber of your pressure bar is probably the second most vital component of the heat sealing process. Having the correct size of silicone rubber and keeping it well maintained is crucial in creating an even seal and preventing the heating element from becoming prematurely damaged.


Choosing the correct size of silicone rubber is an absolute must. The silicone rubber must be wide enough that the entirety of the heating element is covered when the sealing jaws are pressed against each other.

Our recommendations for silicone rubber widths dependent on heating element widths:

  • 5/16″ wide silicone rubber for heating elements that are 1/16″, 1/8″ or 3/16″ wide
  • 5/8″ wide silicone rubber for heating elements that are 1/4″, 5/16″ or 3/8″ wide
  • 7/8″ wide silicone rubber for heating elements that are 1/2″ wide


Keeping the silicone rubber in excellent condition is imperative to prolonging the lifespan of the heating element and producing a quality seal. Pressure must be evenly applied when the sealing jaws close.

Defects in the silicone rubber will create a spot that lacks pressure, thus resulting in an extremely hot spot in the nichrome element.

Hot spots cause the heating element to become damaged and kinked. Subsequently the seals produced will be poor quality until the element is replaced.

Kinking will consequently lead to the breaking of the heating element and permanent damage to the silicone rubber. Additionally damage will occur in the form of the PTFE covers, your product and/or the silicone rubber becoming burned.

Common Problems

Indicators that your silicone rubber is ready for replacement:

  • Cracked and brittle
  • Pockmarks and indentations
  • Burn marks

Stretching the silicone rubber is an additional issue that will result in unevenness and a lack of pressure in some areas. However, this issue is easily correctable.

You can prevent stretching by kneading the silicone rubber into the pressure bar channel without pulling on the rubber. We recommend starting from the center of the channel and working to the edges. When completed, the rubber should not have stretched passed the channel.

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