Glue Strength Does Not Matter

258g Hide Glue in electric warming pot

258g Hide Glue in electric warming pot

What!!??  There is a lot of important information to know about wood glues if you want to be sure you are using the right one for your project.   Strength is the characteristic that everyone seems to agree is the most important.  This is interesting because it is likely among the least important things to consider when making a choice and here is why:

Glues available for woodworking have a higher tensile strength than wood and create a bond that is stronger than the wood that it is joining.   This includes the most common PVA (PolyvinylAcetate or Yellow wood glue) epoxy or even the ancient Hide glue.  Good glue joints don't fail at the joint.  This means we could make an argument that once the joint has been made stronger than the adjacent areas, there is no merit in making it any stronger.  Under stress, the object is going to fail in the same manner and at the same time (somewhere other than the glue joint).   

Some other characteristics of wood glues that are important and could compromise the strength of a joint or just make your job easier are:

Reversability, Repairability, Cost, Creep Under Load, Resistance to heat, Resistance to Bacteria, Resistance to Moisture, Ease-of-Use (need for heating, mixing and clean-up), Shelf Life, Pot Time, Working Time, Toxicity (to the air, soil or us directly), Color, Response to Finishing, Sustainability...    

At the California Workshop, it is a priority to reduce or eliminate toxic and unsustainable materials from our process.   We also need an adhesive that does not creep under load and would prefer one that does not cause the wood to react differently to the finish.  These requirements and the great repairability make Hide glue the first choice of luthiers for centuries and for us today.  

read more at:

http://www.leeswoodprojects.com/woodworking/glue_adhesives.html#AnimalGlue

http://www.naturalhandyman.com/iip/infadh/infadhe.html