Kahrs discoloration due to underlayment

6 May 2011
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United Kingdom
A well experienced installer put in a Lock and Go black underlayment beneath a Karhs cherry engineered floor. At the end of the first day, he put some of the underlayment on top of the floor to protect it from my furniture. The next day, we noticed gray discoloration everywhere the underlayment was on top of the floor. It is particularly bad at the seams between the ends of the boards and within the little seams within the boards.

We've tried water, Bona, acetone, mineral spirits, and Murphy's Oil soap for wood floors, but nothing affects it. It seems to be some sort of chemical reaction between the Kahrs and the Lock and Go.

The installer says he's never seen this happen, as has the owner of the distributor. The manufacturer's rep is coming out to see it today. Has anyone had this problem? Another concern is that (after it's replaced) the slow outgasing of the underlayment will eventually react again (through the floor) and in a few years my floor will have a grayish tint to it.
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