Greetings Patrick,
I know that each bottle of Old Brown Glue has a date stamped on it and the product keeps longer in the refrigerator, this brings the question of exactly how does one know that Old Brown Glue has expired?
Thanks
Robert LaPlaca

The date is very conservative. Tests have shown this glue to remain strong under much longer storage conditions, but environments vary, so we are careful. Three indicators of bad glue: 1) Strong ammonia smell 2) Very liquid viscosity at room temp (should be gel) 3) Visible mold inside bottle. After the "expiration" date always perform a simple test with wood scraps.
Patrick

Hello
Often I'm called upon to fix failed repairs made with hide glue. In a perfect world, I would remove the old glue and then reglue with hide glue or use hot hide glue to reactivate the glue residue. Can your glue be heated enough to reactivate the old glue? Could I use a heat gun to soften the old glue, then reglue and clamp with old brown glue? I am not as lazy as it sounds, but hot hide glue is finicky. Thanks.

Remember that you need both heat and moisture to reactivate glue. Thus, a dry heat gun does not work. Better to use an iron (on low heat) with a wet rag, or just a rag damp with very hot water. Not too much water, not too much heat. You can warm the OBG as much as you like, up to 140-160 degrees. It can be cooled and warmed as much as you like, without problem. It will bond to the old glue fine.
Patrick

Hi Patrick, I received the glue on Sept. 7, but this is the first chance I've had to let you know it had arrived. First off, thank-you for shipping to Canada (not all US vendors ship to Canada).

Just a couple of questions regarding the glue;
- I notice there is a "best before" date on the bottle. Can I extend that?.
- Is it ok to store an open bottle in a refrigerator and warm it up to use when needed (i.e. there are no negative effects from multiple cycles of refrigeration - warming) or once opened, should a bottle be stored at room temperature?
- If the glue exceeds 130 degrees, what is the effect on the glue and are there any signs that it has been "over-heated" (it occurred to me that during shipping in warm weather, it may be possible for the glue to be overheated)?
- Are there any signs that the glue has aged and should no longer be used?
- Are you aware of any issues using water base finishes and the glue?
Hope that's not too many questions. I'm planning to split the glue into smaller units and share it with some friends, so I'm anticipating some questions from them.
Thanks again,
Scott Shepherd

Scott
Refrigeration is recommended for long term storage. Cooling and reheating does not affect the glue and can be done as many cycles as you want. There are three indicators of bad glue: 1) strong ammonia smell 2) visible mold inside bottle 3) very liquid viscosity at room temperature below 70 degrees F. Always test first if suspect beyond ex date.
Do not exceed 160 degrees. It is not necessary. Glue viscosity is best around 100-120 degrees F.
Since water is used to clean up the glue, it may affect water based stains and finishes as well. We use a shellac sealer and finish.
Patrick

While researching hide glue I discovered that hide glue comes in various gram strengths. I've made 2 guitars so far with "Old Brown Glue" and have not had any problems with them so far. But on a "build your own lute" website (http://www.vanedwards.co.uk/glue.htm) the luthier recommended hide glue with a gram strength of 251 and other guitar luthiers on-line have recommended strengths ranging from 192 all the way up to 315. Do you think your Old Brown Glue rated at 192 grams is strong enough for classical guitar building? Is it possible for you to create a special batch of Old Brown Glue with a 251 gram strength rating? Thanks, Jeff

This is an interesting question. Gram strength of animal protein glues is a measure of the force in grams required to push a plunger into the surface of the glue a certain distance, measured by an instrument called a Bloom gelometer.
The higher the gram strength the harder the glue sets and the faster it sets. Lower gel strengths are more flexible and take longer to set. In woodworking the most popular gel strengths are 192 and 251. I have always used 192 (for 40 years) as I like the longer working time. As I am not a luthier, I do not know what qualities are important for your profession. I do know that reversibility is important. My experience with these glues tells me that the difference between 192 and 251 on good wood-to-wood joints is negligible. At this point, I have no desire to produce a version of OBG in another gram strength.
Patrick