STRESS WHITENING:
Generally occurs during first heating season when installation was made during spring, summer, or fall when underlayment board was subjected to some period of high humidity. The boards will absorb moisture and reach maximum dimension, and as the heating season begins, the humidity gets lower, the boards dry out, and as moisture is lost, the boards decrease in dimension thus allowing the joint between two panels to open. As the joint opens, the material spanning the joint must stretch (stress whitening), and in some cases, will even crack and break.
Possible causes:
- Particleboard, Lauan, Masonite, and other unapproved underlayment.
- Hardset adhesives will cause this problem more readily than softer set adhesives that are rubber based and thus have some give.
- Stress whitening on dark-colored materials from severe bending during installation can be repaired. Remove the light mark by heating the area with a heat gun or hair dryer. Do not use a torch. If the whitening is found before the material is bonded to the floor, heating from front and back will speed the procedure.
SEAM WHITENING: Cutting and deburring. When cutting seams in the dark colorations of products, the knife will cause stress whitening. Removing the burr on a seam will also cause stress whitening.
This stress whitening effect can be readily eliminated by:
- Using the appropriate shade of paste wax or shoe polish.
- Rubbing lightly with 3 in 1 Oil.