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About 15 months ago I made up a batch of H.H.G. left it to solidify in an ice cube tray in the freezer.
Wrapped each cube individually in tin foil, sealed these in in jiffy bags, popped them back into the freezer.
Tray was sterilised, and I used de-ionised water.
Any glue I've taken to use has been discarded if there is any left over.
How long do you think this batch might remain usable?
If I reheat it to use now, will the smell (which was very mild and inoffensive originally) tell me if it's still good to use? Any other (quick) quality checks suggested?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Pull the strings/tack test and do a few quick glue ups/destruction tests. I never freeze the glue (not that you can't), just use it fresh. I sometimes leave it overnight but unheated. In the warmer months it certainly spoils much quicker. Once the collagen starts breaking down it gradually becomes weaker. That starts as soon as you mix the glue and heat it, it's a very gradual decay though. Freezing will seriously retard that decay but I couldn't tell you for how long.

IIRC Colin S. and OLFer and a Brit has done some testing and he freezes HHG as well. He would be a good one to ask about HHG freezer concerns.

We mix it fresh, use it, and put the jar in the fridge next to the beer when not in use. We only mix enough for maybe a month and it does not get used every day depending on what comes in to be done. During that month we might reheat it 15 - 20 times and never an issue.

I used to use distilled water but we go through the glue so fast now that I really don't have any concerns about how long it's going to be good since we use it up long before I would be concerned.

That's my problem! I have been putting mine in the fridge next to the dill pickles.

I believe Frank Ford freezes his. You might check his site.

Steve

I'm curious about this as well. I just bought some Old Brown Glue (hide glue with additives to extend open time), and split it up into a bunch of small bottles and froze them. I'll be going through it very slowly, since the only thing I need it for is box closing. The web site says it's safe to freeze, but doesn't give any estimate on how long it will stay good that way. But since the normal expiration is 18 months, I'm hoping it will last at least a few years in there.

I used some from the freezer on braces last month. It was a year old, and no problems with it.

Bob

Thanks all, haven't heard anywhere that anyone uses stuff over a year in the freezer.
I'll just make a fresh batch. Not worth the risk.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

True and it's not as though it takes long to mix fresh, providing you plan ahead by about an hour or so. Either that or make enough to freeze for 3 or 6 months ahead.

In related news, I found a bottle of HHG the other day that had fallen into a box and sat there for who knows how long at room temperature (probably several months at least), and appears completely unharmed. No mold, passes the string test, and makes stronger-than-wood joints. I'll make a science experiment of it and check it again every few months to see how long it takes to go bad

But yeah, with HHG, it's so easy to mix a fresh batch, there's really no point making frozen glue cubes or testing old bottles or anything. The near-infinite shelf life in dry form is one of the things I love about it.

A few years ago, I used to make a large batch, like a saucepan's worth, separate it into lots of small bottles, then freeze the bottles. It worked really well. Each bottle holds a few ounces, you drop one in a warm bath, and the glue is ready to use in a few minutes. However, I started experiencing some bridge adhesion problems here and there. I was never sure what the problem was, but I wanted to eliminate all possibilities, so I revamped my whole HHG process. I now mix fresh every time, and just make a few ounces at a time. In the grand scheme of things, it is no less convenient for me to make it fresh. I have to have a warm bath for the glue either way. This way I know it is fresh, not overheated, not subject to multiple freezes and thaws, not sitting around growing mold, etc. I'm happier.