Silicone is an excellent material for gasket applications. It resists most chemicals, stays flexible over a wide temperature range, has good elongation and doesn’t take much of a compression set. If used where it could come into contact with foodstuffs or beverage products though, it must be food-grade.
This isn’t just a recommendation. If you’re making or handling food the Food and Drug Administration (FDA) mandates the use of materials from their approved list. Here’s what to know about food-grade silicone.
Silicone Basics
Silicone, (notice the letter ‘e’ that distinguishes it from silicon,) is produced by heating silica, (also known as silicon dioxide or SiO2,) with carbon. This produces polymer chains that can be processed into liquids and elastomeric solids and gels.
Solid silicone gasket material is sold in sheet form in thicknesses from 1/32” up ¼”. Important points for gasket applications are:
- Temperature range: -67⁰F to 450⁰F (-55⁰C to 230⁰C)
- Durometer: 30 to 80 Shore A
- Resists UV light and ozone
- Resists most chemicals, except for chlorine, methane and acetates
Why and When to Ask For “Food-Grade”
FDA regulation 21 CFR 177.2600 is a list of materials considered suitable for use with food. Silicone is on the list, but unless you specify food-grade silicone you’ll almost certainly get material that isn’t suitable for use around food products.
Silicone that isn’t food-grade contains additives, mostly colorings, that could contaminate product or make it taste off in some way. Food-grade silicone is white, and for this reason is sometimes called “white silicone”.
Food-grade silicone gaskets should be used in food processing and handling equipment. Storage vessels, kettles, mixers and even freezer doors are all good applications. Be sure to check what cleaning chemicals will be used, as those containing chlorine could damage the silicone.
Hennig Gasket for Food-Grade Material
People involved with food understand the importance of avoiding contamination. No one wants to make someone sick, which is why kitchens and food processors should always use food grade-materials. Stainless steel is ubiquitous for hardware, but when it comes to gaskets, food-grade silicone is often the way to go.
