A Sticky Subject
By Sam Conder
In a “Fundamentals of Woodworking” class I attended taught by Marc Adams at the Indianapolis woodworking show, he stated that he uses ordinary white glue instead of yellow glue for the majority of his joinery. I decided to do a little research on the two types of adhesives and was surprised by what I found.
White glues like Elmer's Glue-All are polyvinyl acetate (PVA) based adhesives. Yellow glues like Pro-Bond and Titebond are aliphatic resin glues, which are merely PVA adhesives with additives to resist moisture. According to the Titebond website a PVA glue is defined as “any glue consisting chiefly of polyvinyl acetate polymer. This category includes both traditional white glues and yellow aliphatic resin glues.”
So why the additives? They must help, right? Well, yes and no. The first yellow glue was introduced by the makers of Elmer's Glue-All, and was called Elmer's Carpenter's Wood Glue. The name implies the need for the additives. Carpenters most often work with lumber with a moisture content around 20 percent (or higher), not the 6 to 9 percent moisture of the lumber used in woodworking. The “glue scientists” at Elmer's found that adding some resins would cause the glue to dry quicker and stronger with this wet wood.
According to Michael Dresdner in volume 1, issue 2 of the Woodworker's Journal E-zine, “White and yellow adhesives are essentially the same thing - PVA (polyvinyl acetate) - 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.”
Marc Adams prefers white glue because of the extended open time, and because it dries clear, where yellow glue dries yellow. When applying glue to a large area, or to a complex area like dovetails, the extra open time allows you to work at a comfortable pace without worrying about the glue setting up before you get things assembled.
The idea of more working time appealed to me, so I bought a small bottle of Elmer's Glue-All and used it to assemble the doors on the entertainment center I am currently building. As expected, I really liked the extra open time, and the fact that it dried clear was appealing as well. Since I just bought a gallon jug of Titebond, I'll have to wait to switch to white glue. But once it's gone, I’ll be a “white glue convert”. I also learned that all PVA glues have a shelf life of about year. So when you buy a bottle, mark the date that you open it on the bottle with a pen and throw it away after a year.
By Sam Conder
In a “Fundamentals of Woodworking” class I attended taught by Marc Adams at the Indianapolis woodworking show, he stated that he uses ordinary white glue instead of yellow glue for the majority of his joinery. I decided to do a little research on the two types of adhesives and was surprised by what I found.
White glues like Elmer's Glue-All are polyvinyl acetate (PVA) based adhesives. Yellow glues like Pro-Bond and Titebond are aliphatic resin glues, which are merely PVA adhesives with additives to resist moisture. According to the Titebond website a PVA glue is defined as “any glue consisting chiefly of polyvinyl acetate polymer. This category includes both traditional white glues and yellow aliphatic resin glues.”
So why the additives? They must help, right? Well, yes and no. The first yellow glue was introduced by the makers of Elmer's Glue-All, and was called Elmer's Carpenter's Wood Glue. The name implies the need for the additives. Carpenters most often work with lumber with a moisture content around 20 percent (or higher), not the 6 to 9 percent moisture of the lumber used in woodworking. The “glue scientists” at Elmer's found that adding some resins would cause the glue to dry quicker and stronger with this wet wood.
According to Michael Dresdner in volume 1, issue 2 of the Woodworker's Journal E-zine, “White and yellow adhesives are essentially the same thing - PVA (polyvinyl acetate) - 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.”
Marc Adams prefers white glue because of the extended open time, and because it dries clear, where yellow glue dries yellow. When applying glue to a large area, or to a complex area like dovetails, the extra open time allows you to work at a comfortable pace without worrying about the glue setting up before you get things assembled.
The idea of more working time appealed to me, so I bought a small bottle of Elmer's Glue-All and used it to assemble the doors on the entertainment center I am currently building. As expected, I really liked the extra open time, and the fact that it dried clear was appealing as well. Since I just bought a gallon jug of Titebond, I'll have to wait to switch to white glue. But once it's gone, I’ll be a “white glue convert”. I also learned that all PVA glues have a shelf life of about year. So when you buy a bottle, mark the date that you open it on the bottle with a pen and throw it away after a year.