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Specialist Materials for Industry and Science

The softer ones

The softer ones

Here we again look at Apiezon Waxes, but with a look at the other two products in the range, Wax W100 and Wax W40. In the article “The Hard One” we looked at Wax W and how it can form a hard semi-permanent seal or be used as an etch resist. These properties are shared by the other waxes, but with two key differences; that they can be applied at lower temperatures and are softer than Wax W when set.

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The lower melting temperature of the softer waxes makes them useful where components that need sealing are more sensitive to high temperature and hence cannot be exposed to the 130°C application temperature of Wax W. Wax W100 is the next product down in terms of application temperature and softens at around 50 to 60°C, becoming liquid at 110°C.  Wax W40 has the lowest application temperature and can actually be applied using hot water as it will soften at 40 to 50°C and be completely molten at 90°C. This makes Wax W40 particularly useful where a temporary seal is needed as it can be more easily applied and moulded around a fitting.

Being softer than Wax W the other two wax products in the range are also very good for mounting very delicate substrates or for sealing glass joints where there might be some vibration. The softer waxes can act to dampen any movement, thus preventing cracking or damage to the glassware or substrate that might occur if the more rigid Wax W was used.

All in all the Wax range offers a product for a wide variety of situations, Wax W is great for a rigid seal, or for etch resist at higher temperatures, where the softer products are excellent when the surface if more heat sensitive or delicate.

Wax W40 has slightly higher vapour pressure than Wax W100 and Wax W, so the harder products are better for high vacuum applications. Having said that W40 is still for use down into the 10-6 Torr range, so is an excellent sealant for a wide variety of applications.



  • Apiezon
  • Metrosil
  • Midel
  • Wolfmet

Products of M&I Materials Ltd.