Hide glue

I'm researching "hide glue". In my searching tonight I came across references to using "KNOX" brand unflavored gelatin from a grocery store. Has anyone done this or even heard of this before?

I looking at using hide glue for gluing the leather to the bellows on my new organ.
It will be gluing leather to a wood frame.

Technically I believe the Knox Gelatin is a "bone glue" which is has a less complex protein mix than "hide glue" and is harder but somewhat more brittle than "hide glue".

If I was starting from scratch with any option open I wanted I'd probably pick either rabbit glue or perhaps fish glue, they aren't quite as strong but are a bit more flexible and the fish is a smidge more water resistant (concerns about condensation inside the bellows as they heat up and cool down during/after use?).

But having said that I'd bet reasonable money on the gelatin working plenty well enough although I admittedly haven't used it in that sort of use case so .... this is more than a bit of extrapolation.

Never heard of using Knox. But, be aware hide glues come in different formulations for specific uses.
Here is a link that I found very informative
http://www.vanedwards.co.uk/glue.htm

Some more data in case anyone else is thinking of using gelatin as a glue, not all gelatins are equal. The "bloom" strength is measured the same as glue "gram strength" (the gram strength is measured using the bloom process so its just two words for the same thing).

TFWW has a pretty decent overview of the various gram strengths
https://www.toolsforworkingwood.com/store/item/ms-hidegl.xx/hide_glue

I was a bit off and knox is towards the high end but not as high as I'd though, more towards the upper mid range.

There are some questions about the gram strength versus stickum power. Gram strength specifically measures how easy it is to deform a cake of the gel under very specific conditions. Some folks claim that glues are a more complex mix of proteins versus the more refined gelatin which increases the stickum power (makes some sense in the abstract), but I haven't seen anyone do a 1:1 comparison and there are certainly people using knox with success in high strength applications (like guitar and violin bindings).

http://www.modernistpantry.com/gelatin-sheets-silver.html
"Gelatin used in food usually runs from 125 Bloom to 250 Bloom" - that's a huge range, the low end there would be marginal for most glue applications.

"The most popular are Silver grade (160 Bloom) and Gold grade (190/220 Bloom).".

Found a bit longer but a more complete list here, which I've preserved a summary table of for posterity in case the link goes stale.
http://luckypeach.com/opusculum-six-things-to-consider-about-gelatin/


If you're doing a lot; plain hide glue is a lot cheaper in volume but the gelatin is easy to get to play with.