Well, I changed my mind. I decided to cut a small sliver of vinyl and insert it into the seam to fill the gap. Very time consuming tayloring the the narrow sliver of vinyl to fit neatly into the gap. It's 1/16" wide or less... most is less than that, none is wider than that.
I cleaned and vacuumed out any accumulated dirt that might have fallen into the gap.
It took a long time to fit these narrow slivers of vinyl. I pulled the skinny strips though a utility knife blade over and over, scraping off miniscule amounts of material until it fit neatly into the gap. Then I put masking tape on the edges of the seam so the sealer didn't melt into the finish.
I applied the PVC sealer down into the gap, then immediately started inserting the skinny ribbon of flooring into the gap. This ribbon of vinyl melted or fused quickly so it couldn't be fully inserted. Pretty close tho.
I pulled off the tape, cleaned off the excess sealer with alcohol and rolled the seam area with my steel seam roller. It fused or melted so fast there is 1/32nd of an inch of my filler strip still protruding above the rest of the flooring. I'm borrowing a seam skiving knife
(part of a heat welding kit) tomorrow to see how neatly it will trim this excess material flush with the flooring. I'm thinking this will work out pretty nice.
I am a bit PO'd that any manufacturer these days makes a commercial material that expands an contracts so easily with varying room temperature.
I mean, I had this flooring unrolled and layed out flat in the living room floor for two days maybe three before I installed it. The place was warm. The actual floor temperature was 74 degrees. A week later after the hardwood floor guy was out of there, I arrived to see these gaps in the seams...... the heat was off.
Jonsonite says to wait at least 2 1/2 hours to chemically seal the seam...... they do not add to seal the seam within a certain period of time.
It hasn't continued shrinking. The gap opened up within a few days and hasn't changed in weeks.