Today we will be looking at the common question of which glue should a woodworker use, white glue or yellow glue?
I hear this question often. And like everything in woodworking, it is more complicated than it seems.
Actually, the only real difference between yellow and white glue is the color of the dye that is put in.
They are both the same kind of PVA glue. PVA, by the way stands for Poly Vinyl Acetate.
As far as the strength of the glues, all PVA glues bond stronger than the wood. I you have a proper glue joint, then a stressed joint will crack within the wood
itself, and not along the glue line.
So the bond strength of PVA glue becomes stronger than the wood itself, so bond strength between white and yellow glue makes no difference.
So, then you ask, why are there so many different kinds of glues?
Well, besides the color, there are differences between PVA glues.
Actually the color can come into play because white glue will dry clear, and yellow glue will dry more yellow. So depending on the type of wood you are using, you might
want to use one that will minimize the glue line.
In general, white glues soften more easily with heat. This can come into play more often when you are sanding the joint. Sanding creates heat and will re-soften the
white glue more easily and so it is harder to sand than yellow glue which stays harder under the heat of sanding.
One solution to this is to use a cabinet scraper to remove the glue instead of trying to sand it off.
Another difference in PVA glues beside the color would be the open time (how long the glue takes to start getting too tacky to work with). This for me is actually one
of the biggest factors.
So the answer to the original question still remains that color, white or yellow, means nothing because the glue is colored for mainly marketing reasons.
So what to do?
Only focus about the other properties besides color - i.e. sanding characteristics, initial tack, open time, complete drying time, and which one of these factors is most important for your specific project.