Crack Beading or Poly BB's:
The Problem:
Beads of finish forming in the side joints.
The Cause:
Most finishes and stains dry from the top down. When the first
coat is applied, whether it is a stain or finish, it seeps down
into the cracks between the boards. The material therefore stays
comparatively wet because there is no air movement. Usually,
at this point three things happen:
As additional coats are applied, the problem
is compounded. Then covering the floor may affect the dry time
by locking the solvents down in the cracks. In time the floor
expands and contracts. Expansion pushes the boards together
and the still wet material down in the gaps is squeezed up,
forming the beads.
How to fix the problem:
It has to be understood that this is NOT a finish problem. How
to know? The finish looks great on the face of the boards for
all coats; the only issue is the cracks.
The solution to the problem is time.
Allow the floor to expand and contract and just keep removing
the beads that have cured or hardened with a putty knife or
scraper. DO NOT attempt to screen the beads off, this will cause
circular scratches in the surface of the finish. If there are
bb's that are still soft, remove them with a scraper then wipe
the area with a rag dampened with mineral spirits.
How to avoid in the future:
Apply the sealer, stain and or finish as per manufacturer's
recommended instructions using the correct coverage rate. Remember
more is not better. Watch for excessive cracks. These can be
trowel-filled (as per manufacturer's instructions) Also pay
attention to the factors that affect dry time. Floors should
be installed at normal living conditions. That means, with all
windows and doors in place, all wet trades done and the HVAC
system running. It is important to control the job site environment.
Avoid high relative humidity, above 90% R.H. and lower temperatures
below 50 degrees F (10 C) that can seriously slow the drying
time of sealers, stains and finishes.
Once the floor is finished, allow it
to cure appropriately before covering. Check the manufacturers
technical sheets for correct dry times.
