The primary glue that comes up for reversible glue is “Old Brown Glue” made by Antique Refinishers in San Diego. I can remember the name of the glue in the video but I think this the same one. It is a modern formulation of traditional glues made from animal protein and urea. The original had to be kept hot to have the proper viscosity. Old Brown Glue is touted as having the same properties but can be used a room temperature. It is a protein glue (hide and bone) and not a synthetic, but they do not say whether bunnies or cows were used. The link to W. Patrick Edwards’ (maker of Old Brown Glue) article on period glues or protein glue is below.
Period Glue Article
As to the issue of reversibility…
Edwards writes synthetic glues form a bond through a chemical reaction, changing from one chemical to another and therefore are not easily reversible. But protein glues do not change their chemical to bond just change from liquid to solid.
To break a bond he suggests drilling a small hole into the joint and then use a syringe to inject hot water. Alcohol or vinegar can also be used since it will make the glue brittle allow the bond to break apart. To remove veneers, steam is suggested.
The characteristics of Old Brown Glue per the manufacturer:
Liquid at room temperature
Can be thinned by heating or thickened by cooling
Dries by loss of moisture
It takes about 1 hour to set up
Cleans up with cold water
Sets within 24-48 hours under normal conditions
The bottles are dated and shelf life is approximately 1year
5oz bottle is $8/ 16oz is $20 plus shipping and handling
Old Brown Glue home page