I'm currently looking for a tubing that can withstand 350F+, have a shore rating of less than 80A, and must be impermeable or very close to it.

I've found a tubing called "Viton" which is close but not quite impermeable; are there any other materials offered out there that fit these specifications?

  • $\begingroup$ You have to define what you mean by "impermeable" in order for someone to give you a good answer. Also the wall thickness of your tubing is going to affect permeability, how thin do you want your tubing to be ? $\endgroup$ Commented Jun 14, 2018 at 19:51
  • $\begingroup$ McMaster-Carr would be a good resource for this type of search. $\endgroup$
    – ericksonla
    Commented Jun 14, 2018 at 21:32
  • $\begingroup$ Impermeable meaning that water vapor or odors cannot penetrate it. I've searched McMaster. $\endgroup$
    – Sam W
    Commented Jun 14, 2018 at 23:02
  • $\begingroup$ Hi temp silicone rubber would be a good starting point. Fluorosilicone rubber would have the best chemical resistance, if you can find it :-) $\endgroup$ Commented Jun 15, 2018 at 0:11

2 Answers 2


Check out ePTFE tubing.

Water impermeable and bio-inert. Strong, can be really thin, and can be softer than 80A.

Regarding odor impermeable, you'll have to test.

  • $\begingroup$ Teflon has a hardness of 98 on the Shore A scale, not what the OP is looking for. $\endgroup$ Commented Jun 15, 2018 at 21:52
  • $\begingroup$ That's PTFE. Look up ePTFE, e is for expanded and is much softer. $\endgroup$
    – Tim D
    Commented Jun 18, 2018 at 14:28
  • $\begingroup$ Really, you are suggesting foamed Teflon, what will happen to your permeability? $\endgroup$ Commented Jun 19, 2018 at 3:23
  • $\begingroup$ PTFE is permeable to Cl ( and likely others) at moderate temp. like 150 F. I have seen many magnetic stirrers ( magnet encased in 1 to 2 mm thick PTFE) swell and even burst while stirring water solutions for corrosion testing) .Cl ,etc . permeates and corrodes the magnet material. $\endgroup$ Commented Aug 11, 2018 at 0:04

Viton is about as close to "impermeable" as it gets. Viton gaskets are what are commonly used for ultra-high vacuum chamber systems which can achieve vacuum levels on the order of 10E-12 Torr.


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