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I've read that adding 15% salt to 251g hot hide glue increases open time. Has anyone tried this? How does it affect the bond?

I don't use it I also know urea will do it. Best I can tell you is experiment and let us know your result

Thanks John.

My gut reaction, based on nothing, is that it would negatively affect the bond strength. I think it would make the joint tend to absorb moisture from the air, among other things. I think the salt would crystallize in the glue and weaken it that way, as well.

But I have no actual data to base that on.

My gut tells me the same thing Steve. I prefer not to add anything to my hhg. But, I had someone ask about it, so I thought I'd experiment.

to gain a bit of time heat your part
I use a infra red heat lamp from home depot

You can do a strength test
clamp lightly for 12 hrs see how much grain pulls with the glue

Its fascinating to me that hide glue has been used for hundreds of years, with and without the urea trick, but there seems to be very little technical data out there on bond strength - by glue strength, mix ratio, additives, etc.

One data point is the FWW article on glue strength - in it Old Brown Glue, which is 192 g Milligan & Higgins hide glue with 46-0-0 urea, outperformed hot hide glue. So from that ONE data point, I conclude that additives don't weaken the joint - heck, apparently they strengthen it! Lol!

I think this is very interesting, will be fun to see what further testing reveals.

having used hhg brown franklin
I learned a good bit I think more is on technique
Cold hide was changed a few years ago and I stopped using it.
I know old brown is intersting. My dad used to use that before tite bond came out.

Steve Latta is Federal Period furniture reproducer and a heckuva an instructor. I saw him for the 3rd time in Williamsburg 2 weeks ago during their annual woodworking conference. He uses Old Brown Glue and says stay away from Franklin. He keeps a pot of warm water (not hot) with a plastic syringe in it for gluing his little parts together.

I have also seen Patrick Edwards at the conference - he copies 17th c intarsia and marketry using hand tools - and he is the guy that developed Old Brown Glue and started making it perhaps 15 years ago. Two years ago he said that every bottle sold was made on his kitchen range.

I like OBG for furniture, and I have used OBG for bridges a couple of times - so far so good perhaps 3 years out.

Ed

I got a bottle from Amazon of old brown glue and it was hard. Would try it if I can find a good source