Making the case for Liquid Hide Glue
Yes, Hot Hide Glue is better [whatever that means] than Liquid Hide Glue. It has a greater strength. However Liquid Hide Glue is better [and I know what that means] than any modern glues.
Hot Hide Glue is the benchmark to which all glues are compared as it was one of the first glues used by humanity. Hot Hide Glue is mentioned in all Adhesive Technology references right up front, first thing and it is the adhesive to which all others are judged against.
Many groups like [I have been told] the Society of Period Furniture Makers and many luthier groups do not like liquid hide glue and only use hot hide glue, and there is nothing wrong with that. However dismissing liquid hide glue out of hand is a bit much.
Liquid hide glue is a far better choice than any modern glue because of the many reasons that I have mentioned before here and in Hide Glue – Historical & Practical Applications. Liquid hide glue because of the anti-gelling agents added has lost about 10% of the strength of hot hide glue. Adding things like alum to make it waterproof, or glycerin to make it flexible, or bone dust as a thickening agent also reduces the strength of hot hide glue by 10%. So altered hot hide glue and liquid hide glue still has a shear strength in excess of 2800 psi.
Old Brown Glue, Lee Valley Fish Glue, and Franklin/Titebond liquid hide glues are all available and are all very good. People complain about the shelf life, but if stored at low temperatures the usable life of the glue can be extended for years. The problem most people have with liquid hide glue is the stuff they used was too old.
Do the stringing, cottoning, legging test to see if it is fresh enough to use. Place a small amount on your thumb and index finger of one hand and touch them together repeatedly. Fine filaments will appear in an ephemeral looking smoke if the glue is fresh. If not it has expired and can be thinned and put in the garden, high in nitrogen.
I use both in my work but to be honest I use more liquid hide glue than hot hide glue and I have not had any trouble with making furniture using liquid hide glue or for many repairs. The stuff is easy to use, convenient and has all of the benefits of hot hide glue [less 10%] and none of the drawbacks of modern glues.
Easy to clean up, now, tomorrow or a hundred years from now, does not suffer from creep, is largely transparent to stains and finishes [glows under UV light for easy removal], is reversible and washes out of your clothes. And it is organic and contains no petroleum distillates and is renewable.
Hot Hide Glue is great but so is Liquid Hide Glue, give it a try.