thread Yeah, that is kind of what the Weldtite stuff was like.
It served dual functions - had less chance of a puncture (because there was a barrier) and attempted to close up punctures - fine at 30PSI with a Swampthing, probably fuck all use at 110PSI in Gatorskins.

If you are as fat as I am then 20mm tyres are not worth the effort, they end up being as wide, if not wider, by the time I compress them.