H&S airbrushes use Teflon or PTFE whitch is absolutely solvent resistant or proof if you like, and unlike some other brushes it is used to sealed both end of the paint reservoir and the models with screw in cups have a Teflon seal around them too .
Teflon is a polymer that has a relatively low elasticity and elastic pressure so if you go beyond that limit it will permanently stay that way. On the plus side, Teflon has a very low coefficient of friction so the use around needle seals should make them very slick with the right pressure.