I have an art project where I'd like to carve a jack-o-latern, let it decay slightly (think post halloween, pumpkin left out, slightly melting face) and then cover the result in chrome, or a similar mirror finish.
How can I preserve a jack-o-latern for posterity, while still getting the decaying effect?
I was thinking that something like dipping the carved pumpkin in bleach and then letting it dry, then adding some sort of protective clear coat might work well.
I would be much easier for you to carve the shape out of some material (polystyrene, soft wood, soft cements...) and then paint them to your taste.
BUT, if you really want to use biological specimens, you need to look at the method named plastination. The Wikipedia article does not go into all the details, but if you research a bit more, you will find information.
My worry is that you will need to waste a lot of time and a lot of material before you can consider yourself successful. Or you could just buy a license and their materials to use the technology.
Note: I am in no way affiliated with the people, companies or technologies (directly or indirectly) referenced in this answer.
Bleach will kill microorganisms on the surface, but it doesn't penetrate very far. If you want to let the pumpkin decay to the point that the structure starts to break down, bleach won't halt the decay. You would need to preserve it using a method that preserves biological specimens. I know immersing it in formaldehyde is often used. I think there is also a way to immerse it in successively less diluted alcohol. I'm not up on the subject, but it would be easy to research.
Once you stop the decay and preserve it, it probably will be rubbery (at least the decayed areas), not rigid like a fresh pumpkin. It will also probably be very wet and difficult to dry to the point that you could paint it, at least without dehydrating it, which would change its appearance. To have something solid, you might need to create a mold of it and then cast a replica. There are relatively inexpensive ways to do that, which could make a good subject for another question.
As for the chrome effect, I have some ideas as well:
Spray-painting the result would work to get a chrome look. You wouldn't be limited to a specialty paint. You can buy chrome spray paint inexpensively at paint, hardware, or auto supply stores.
It might be less work to just make the entire Jack-o-lantern from clay.
