Gortex, also known as Gore-Tex Sealant, has been capturing a piece of the sealant market. How is it different from a Viton ® (FKM Fluoroelastomer) rubber sheet sealant? And which is better to use?
First we need to discuss what Gore-Tex sealant is. It is a PTFE fluorocarbon material, but it is very different from other rubbers made from PTFE. Gore-Tex sealant is very strong, but its appearance is very deceiving. It has a very soft spongy appearance. Gore-tex seals can come in a seal ready to be installed, or can come as a continuous cord that you use to form your own seal.
One of the biggest advantages of the Gortex seal is the softness. It can be used in areas with uneven edges where most seal materials will fail. Viton ® (FKM Fluoroelastomer) rubber is a much stiffer material and should be used to seal two prepared and even surfaces.
The softness allows the material to be used with more fragile materials, also. Softer plastics and glass can be sealed with Gore-Tex and not be shattered due to the cushioning effect of the softer sealant.
Being soft is not always the right solution. Gore-tex cannot as easily be formed into sheets for seals and gaskets, which is an area where Viton ® (FKM Fluoroelastomer) rubber excels. The softness does not provide an advantage in most common sealing situations either. If you are sealing two well fitting parts, Viton ® (FKM Fluoroelastomer) Rubber can provide a tight seal with more durability than Gore-Tex.
The temperature range of Gore-Tex is almost unimaginable. It can be used in applications down to an astounding -269°C and up to an equally impressive 315°C. This gives it one of the highest temperature ranges of common sealing materials. Viton ® (FKM Fluoroelastomer) Rubber provides a temperature range of -26°C to 230°C, which satisfies the needs for most applications but falls far short of the range of Gore-Tex.
Both Gore-Tex and Viton ® (FKM Fluoroelastomer) Rubber are used in a variety of applications involving chemical processing. Viton ® (FKM Fluoroelastomer) is outstanding when dealing with petroleum products, hydraulic fluids, vegetable oils and a wide variety of other chemicals. Gore-Tex is commonly used with acids, alkali and solvents.
There are many crossover applications between the two materials, but most commonly Viton ® (FKM Fluoroelastomer) Rubber will be the most cost effective choice when it can be used.
Many PTFE and ePTFE materials, like Gortex, are known to have problems with creep and cold-flow. What this means is they can move even while cold. The creeping means the entire seal may move out of position over time. Cold-flow means the seal may ooze out into the pipe, or outside, slightly. This can cause slight restrictions in material movement through the pipes. Some Gore-Tex materials are now designed to reduce both creep and cold flow.
Viton ® (FKM Fluoroelastomer) rubber does not have any issues with either creep or cold-flow. It is a material with more resilience and will stay in-place as applied throughout its life.
Both Gortex and Viton ® (FKM Fluoroelastomer) rubber have important places within the sealant industry. You are probably starting to see where they have some crossover in application, but they also have more differences than many sealing material competitors.
When you need to seal irregular or fragile flanges, Gore-Tex PTFE is superior to Viton ® (FKM Fluoroelastomer) rubber. Viton ® (FKM Fluoroelastomer) rubber is superior in applications where a strong seal is needed between two smooth, or regularly shaped, items.
Gore-Tex provides a temperature range that Viton ® (FKM Fluoroelastomer) rubber cannot match, but within its temperature range Viton ® (FKM Fluoroelastomer) Rubber can provide a more durable and secure seal than Gore-Tex.
One of the other big differences is in chemical resistance. Gore-Tex’s PTFE formula has a wider range of use than Viton ® (FKM Fluoroelastomer) rubber, but with the added cost. Viton ® (FKM Fluoroelastomer) rubber has become a top choice in the automotive and aeronatuics industries for its excellent chemical resistance paired with reasonable cost. Viton ® (FKM Fluoroelastomer) is resistant to mold, mildew, fungus and other items which are commonly battled in both industries.
Are these two materials direct competitors? In some situations they can be, but due to their differences in strength, softness and pricing it is usually an easy decision for engineers to make. Evaluate your needs carefully when comparing the two materials. If you need the extreme capabilities of Gore-Tex then it is one of your few choices, but if you need a great balance of capability and price, Viton ® (FKM Fluoroelastomer) Rubber could be the answer.