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Comment by chrisco255 | Hacker News Reader

What's most impressive to me is how razor sharp the slate arrowhead they show in the top photo is. I've seen photos of many stone age arrowheads but they are usually much more dull and blunted.

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That's because they weren't exposed to the weather as much. Essentially these were 'shrinkwrapped' in nature's own version of Cosmoline. No bacteria, no free oxygen. Once did this with a rose to see how long it would last and it basically was perfect until we moved house. Many years and not even the slightest change, it didn't even lose color.

That would actually be a brilliant treatment to give wedding bouquets! I’ve never heard of Cosmoline. Going to look it up. Thanks!

It's not so easy to freeze something that large without getting defects in the crystal due to different rates of freezing, to do that properly will be a major engineering project. But I'd love to see you succeed with that.

I’ve never heard of Cosmoline

Ironically it's made of petroleum, which is the decayed remains of prehistoric organisms.

That's part of the story. The petroleum based part will go in a few years, what remains is the protective layer of wax that matters. I've bought some military surplus stuff that was coated in it, at first I didn't know what it was and then once I found out about it (and how to remove it) I was super impressed by how effective it is in preserving all kinds of materials from time's teeth. In particular these were parts for a 1940s vehicle, NOS that came out of the covering as though made the other day.

The petroleum based part will go in a few years, what remains is the protective layer of wax that matters.

??? The wax is petroleum, just the heavier parts.

Fair, I should have used 'waxy matter' but up close it looks like wax more than anything oil related. But you're totally correct.

You can make your own cosmoline by dissolving a wax toilet seal ring (a new one please) in mineral spirits. Prevents rust for decades.

my lathe also came wrapped in cosmoline and shrink-wrap

it's slate, bacteria and free oxygen won't do anything to stone...

But the weather does over those timescales.

And the wood of the arrow would be gone otherwise.

Stone is not inert and is absolutely consumed in biological processes. Lichens will grow on stone and reduce it to dust over aeons.

https://pubs.geoscienceworld.org/minersoc/books/edited-volum...

That, plus stress from thermal cycling.

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