Originally Posted by Arthur Peabody

But they don't seal.


That I put some time into it doesn't mean I expect anyone else to. I asked in case they had.


I don't know everything. I make mistakes.


There may be some substance I could paint on a tube that would decrease its permeability; I suspect something on the inside would be more effective, perhaps sealant. Tires aren't airtight.



Mine aren't.



I used in my example butyl rubber. I hope there are better substances.


I calculated theoretical air loss from first principles plus figures for the permeability of butyl rubber to nitrogen and oxygen from the NBS.


Yes. From the model of permeation the thinner the tube the more the permeation. There are thicker tubes too, usually sold as thorn-resistant.


I bet it doesn't work. You'd have to paint it on before you inflated it; the expansion would crack. I doubt FlexSeal would hold up to high pressures.