Resin shelf life?

What’s the typical shelf of bottles of polyurethane resin?
I got a few projects in the near future that I might have to cast a few bits for. I’ve just checked if my bottles are still ok to use and this is how I found them.

Part A’s bottle has distorted and it’s settled. It does seem to mix back up if I shake it. Part B though seems to be worse as it’s gone thick and gelatinous with blobs floating in it. They’re about 2 or 3 years old.
Obviously, these are no good and will have to be disposed of.


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Think I’ve just answered my own question posting the photo.
Just seen the small print on the side saying 6 months.

Yeah, definitely need new bottles. Hopefully something smaller so I can avoid waste.

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Why don’t you try a sample mix and see ?
I use epoxy at work that can be brought back if it cristalizes by putting container in a bath of warm water then stirring…


Thanks. I think I will.
All I want to do is cast some machine gun boxes for stowage. So I don’t really need big bottles of the stuff.
Somewhere I have got some moulds from the last thing I cast. If I can find them I’ll give it a try.

Just mix a little in a cup or small mold made of kitchen foil . The only thing you need to discover is if it will still cure properly and pick up details.


That’s a good idea, hadn’t thought of that.
If it has gone bad, I don’t want to ruin those moulds!

What I want to do is make some copies of the the ammunition boxes from CSM’s French AC to use in their Belgian Minerva. Different guns yes, but they used a similar 25 round strip. From what I can see online, the boxes are very similar.
I could scratch them from styrene, but it would be more time consuming.

Yes, approximately 6 months as you’ve discovered. I have some that is several years old. It’s useless for casting detailed parts.

It bubbles and expands during cure time. Final results are full of bubble holes. I still use it for weight by pouring the mix into figure bases. If you want to cast a meteorite, it’s perfect. Maybe for a moon base or another planet base for a diorama :bulb:

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That’s an interesting idea! I’ve got a couple of small Star Trek shuttles that a meteor base would be perfect with.
I’ll give it a try and see what happens. I’m shopping around for some smaller bottles. I might see if there’s anything else I could cast to avoid future waste.

It’s the only sure way to find out!

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“It’s the only way to be sure…”


Stephen. As per above, test it by before using it, even for bases and leave it for a while too. Old resin may weep poly oil over time and this can soften styrene and will lift paint (ask me how I know.)

Resin that weeps oil usually never stops weeping no matter how you try and dry it, seal it or otherwise treat it.


I’ve had resin items I’ve bought in the past do that. Really greasy to.

I’ll try the stuff over the weekend and see what happens. Think it will be interesting!


I have used this acrylic resin from Green Stuff and I like it a lot, although the result is not as strong and smooth as traditional resin (seems more like plaster), for small projects like yours it works fine. Just needs to be mixed with water, and being powder I expect it to last almost forever…

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Thanks. That might just be what I need.
I’ll do a little shopping around.