SpudFiles

latex paint.

It dies as a flexible plastic which can take the force of opening and closing.
It seals great and has low surface friction.
And it can be in any color you choose!

Anyone want to test this?

IIRC latex can only cure in air (I think it's the moisture) and so you can't make something 30mm+ thick as it'll take years before it's ready.

That's why when making moulds you only have thin layers and you keep painting it on....

I think.....

You could just coat something in a few layers of paint and it would still work in the same way, wouldn't it?

hmmmmmm very interesting... its giving me ideas

I agree with those who say that it will take forever to cure; and from my experience, latex isn't the most durable thing ever. I have the feeling that the force experienced by a piston valve would destroy it.

The problem with latex is that it is pretty much solvent based and just dries; it doesn't cure through cross-link with a catalyst, like epoxy does. I don't really see any reason to use it over epoxy. I don't see the point in coating something in several layers that have to dry over time, when you could just mold it out of epoxy in one shot and be done with it.

Speaking of paint though, I've worked with some different epoxy-based paints in autobody repair that cured hard as a rock after a couple of days. We put some leftover epoxy primer-surfacer in a plastic cup, and once it was fully cured, it was so hard that we could chuck it on the cement floor without chipping or cracking. But then again, that stuff would be too expensive for this type of use... probably about 10-15 bucks worth to make a piston.