What’s the difference between white and yellow glues? Are their guidelines for using one or the other?
Rob Johnstone: Amy Jo Morris, a technical service person at Franklin International, had this advice. White glue and yellow glue have about equivalent bonds after they have cured. White glue remains just a bit more elastic than yellow after curing. Yellow glue sets up faster and resists moisture better than white glue.
Ian Kirby: White glue has a longer “open time”?the time you have between starting to apply it and getting it into the clamps. It also has a longer “closed clamping time”? the time it must remain in the clamps before it sets.
Some of the yellow glues have improved resistance to moisture. Both glues are strong enough in normal use. White glue was the first to appear on the market and in the early days it had a poor resistance to “creep”? it wasn’t used on chairs. This defect has long been put right and both glues are strong enough in normal use. It seems to me that yellow glue is most often used, not for its slightly greater strength, but for its increased rate of cure.
Michael Dresdner: White and yellow adhesives are essentially the same thing – PVA (polyvinylacetate) – and are therefore fully interchangeable. Yellow glue was introduced with a bit of coloring in it to distinguish it as a higher quality product. Typically, it has a higher solids content, is a bit thicker, and often has a faster tack time. None of these issues has much of anything to do with strength, but rather of handling properties. Thicker, faster tack yellow “glue” does not run as much and lends to easier assemblies in some cases.
In the guitarmaking field, most parts are assembled with yellow PVA, but bookmatched spruce guitar tops are always edge joined with white. The reason? The white version does not leave a discolored line down the center of the bookmatched top. In fact, a good joint is virtually invisible. Use whichever works (and looks) better for your own work.
By the way, within the adhesive industry, natural materials are called glues (hide glue, fish glue, rabbit skin glue, etc.) while synthetic materials are called adhesives. White and yellow “glue” are both adhesives.