One of the most common veneering glues is PVA
What is PVA glue?
PVA glue stands for polyvinyl acetate.Without going into the chemistry, it is basically white glue, or some people just call it Elmers glue. It is a staple in the woodworking industry. It is one of the easiest glues to use for veneering as well.
PVA glue works by intertwining the fibers of the wood together. Then when the glue dries, the two pieces are physically connected together. Visit here if you want to know more about how PVA glue works for woodworking.
Do I need special equipment to use PVA glue for veneering?
Before you use PVA glue for veneering, you will need a press. It can be a vacuum press, a screw press, or just a way of applying strong even pressure on your veneering piece. With smaller pieces of work, this can be done using a only a veneering caul and some good clamps.
Why do I need a press for veneering with white glue?
White glue is a water based glue. (It's solvent is water). When it comes in contact with wood, the water gets absorbed by the wood fibers and they swell up. In woodworking, when you coat a piece of wood board with PVA, nothing dramatic happens, because the piece of wood is thick.
Only the fibers on the surface of the wood are affected but because of the thickness of the wood, the moisture content that the glue added will not be strng enough to warp the board in any way.
But when you apply PVA glue to a piece of thin sliced wood such as a veneer, the moisture that the veneer absorbs will make it curl up. This is because one side of the veneer has moisture, and the other side does not. The results in only one side of the veneer expanding, as the fibers absorb the water from the glue, which causes the veneer to curl.
A caul and a press are needed to keep the veneer flat to the substrate after you have applied the glue, otherwise you would be left with a wavy or curled up piece of veneer that you wouldn't be able to glue flat to anything.
Is white glue better than yellow glue for veneering?
This may come down to personal choice. They are both PVA glues and are almost the same. I use basic white glue because it has a longer open time. However, both white and yellow glues are so similar in properties that it does not make a difference as to the end product. There are really only two differences that may be an issue.
Firstly, white glue will dry clear. Yellow glue dries yellow. If there is any kind of a glue line that may be visible in the final project, white glue would be the better choice. Also, if there are any accidents (which of course, never happen in your shop), or glue seeping through the veneer for some reason (some veneers have larger pores that glue can come through), the clear white glue has an advantage.
Secondly, the open time on white glue is a few minutes longer. This means that you will have a few extra minutes of being able to work with the veneer and substrate before the glue becomes too sticky to work with. Because the amount of glue being applied is only a thin coat, it does not take very long before the absorption of the moisture from the glue into the wood makes it so that the veneer will not be able to be adjusted.
As for yellow glue, one advantage is that there are formulations that are water resistant for example that may be needed, however there may be other better glues to use in that case.
What are the advantages and disadvantages of using PVA glue for veneering?
The advantages are:
- Long open time
- Easy to apply
- Easy cleanup
- Dries clear
- Can be reactivated by heat (to fix bubbles)
The disadvantages are:
- Need a press
- Glue line may creep
- Water based solvent