When laying up raw
wood veneers, they should be flat and flexible for best results.
If the veneer is very dry and rippled, it can crack in the pressing
process. Also, if it is being applied to a curved surface, like
a raised panel door, it will not flow in the curved area
To solve this
problem a veneer softener is used. There are formulas for making your
own softener or you can purchase commercial softeners like our VKS
veneer softener which is diluted with an equal amount of water. It is
sprayed on both sides of the veneer (P1) then placed in the VAK Bag
with plain paper on both sides and a caul on top. Do not use newspaper
on top of the veneer as the print could stain the veneer. Brown paper
bag or tissue wrapping paper is good(P2). Newspaper can be used on top
of the plain paper. When under vacuum, the moisture gets wicked out
from under the caul and will evaporate faster when under vacuum. It
helps if you add a mesh (plastic window screen, etc.)(P3) in with the
paper (not on the veneer) as this helps wick the moisture out faster.
You should change the paper several times to speed up the process.
Place the assembly (P4) in the vacuum press and apply vacuum.
When your remove it
from the vacuum press, check the moisture content to be sure you are
back to the correct moisture level, moisture content (MC)(P5). This is an important
step and needs to be addressed with a moisture meter. If the MC is
too high when it's pressed, the veneer will have expanded. When it's
out of the press and fully dried it will want to shrink and this can
cause crazing/cracking on the surface. It depends on the wood and the
MC as to the extent of the cracking. Also, be sure to measure the
center as well as the edges when checking the MC. When in the vacuum
press, the edges will dry faster than the center.
Once the veneer has
softened and brought to the correct MC, it should stay that way for
several days depending on the conditions it will be stored under.
It's best to use it within a few days after the softening process has
This is a image on
how flexible the veneer will be after veneer softener treatment.
1/2 Gallon Veneer Softener makes 1 gallon.