A.Merrill Glos,
engineer at Formica Corp., responds: The most
common cause of bubbling laminate is dimensional
incompatibility between the laminate and the
substrate. To prevent the problem, the substrate
and the laminate must be compatible — they
must respond to humidity changes by expanding and
contracting at the same rates — and they
must both be acclimated to the indoor environment
before they are bonded.
If the laminate is dry and the particleboard is
wet, the laminate will bubble when the laminate
grows and the substrate either shrinks or stays the
same size. It takes laminate about two days to
acclimate, if air can get to both sides of the
material. For a piece of 3/4-inch particleboard
substrate, it takes about a week. The best
substrate is particleboard, which has good
dimensional compatibility with laminate. Plywood
makes a poor substrate, because it is more
dimensionally stable than laminate.
Solvent-based adhesives are preferable to
water-based adhesives. When it comes to dimensional
movement, wood reacts with moisture, not with
solvent. Even with proper acclimation, if you use
water-based contact adhesive, the water can disrupt
the humidity balance by introducing water into the
laminate or the substrate. Solvent-based adhesives
tend to be more forgiving than water-based
adhesives, and do not induce dimensional change
problems.
To solve the problem, you’ll have to
heat up a larger area of the laminate than just the
bubbled area. Heat up the bubbled area, as well as
the entire area from the bubbles to the nearest
laminate edge. This will allow the laminate to
slip, adjusting to the change in dimension. After
heating, use a 3-inch J-roller to rebond the
contact adhesive, rolling until the adhesive is
cool and has regained its strength.