Hydrophobic Rubber

Most elastomeric polymers used to make gaskets are hydrophobic in the macro sense, meaning they do not absorb water. On a finer scale, the surface texture, surface residue, and cell structure factor into the “beading” effect commonly associated with hydrophobic materials.

Hydrophobic Example: Neoprene sponge manufactured in a thick bun is sliced to thinner sheets. The sheets have a fine surface texture due to the cut cells; this increases the surface energy and restricts beading to a degree.

Generally, the hydrophobic quality of a material is less of a consideration than whether it is an open cell or closed cell material. Solid rubber gasket materials are all considered to be closed cell. Expanded rubber gasket materials can be either open cell or closed cell. Open cell materials allow water to flow from one cell or pocket to another. Under heavy water environments, open cell gasket materials will allow water to wick thru the gasket wall. Closed cell gasket materials have a structure where each cell or pocket is closed off from one another. This closed cell structure allows for a soft gasket with water sealing properties.

Open Cell Example: A kitchen sponge is constructed with open cells; the cells hold water used for cleaning.

Closed Cell Example: A scuba diver’s wet suit, where the closed cell neoprene is soft and lightweight yet does not absorb water even under pressure of being submerged.

Stockwell Elastomerics Hydrophobic Materials

Stockwell Elastomerics inventories a broad range of hydrophobic silicone, neoprene, and EPDM rubber materials. Custom molded silicone parts are also available for unique sealing applications.

Common Materials:

• NORSEAL® (formerly COHRlastic®) R10470
• NORSEAL® (formerly COHRlastic®) R10480
• BISCO® HT-800
• Liquid Silicone Rubber (LSR)
• Neoprene Sponge
• EPDM Sponge