“Tender coat”

Q: I am having multiple problems with my new hardwood floors. The floors are oak, natural poly finish. First off, My floors have scratched very easily despite waiting several weeks to walk on them, and using a vacuum made for hardwood floors. I have had other hardwood flooring installed in my home and never had this problem.

I had them put another coat but this time there are the swirl marks everywhere as well as bubbles. There is also a bright yellow stain in the middle? It looks like it could be a stain under the finish. These floors are brand new. The company said they would come back again but they are stumped as to why the floors are scratching so easily and how to fix the swirl marks. It is a reputable company.

A: You haven’t told me the type of finish used, whether water or oil borne, but I will take a shot. Marking easily? If they have used a decent finish, it sounds like you have what could be called a tender coat. This situation happens when multiple coats are applied before allowing sufficient time for the previous coat to dry, regardless of the finish technology used. In the one case, the solvent, mineral spirits get locked in the finish and will take some time before a full cure is achieved. Likewise with water borne, a small solvent content and small water content get trapped and time is the cure (no pun intended) There are several things that can contribute to slow drying, including environmental factors such as temperature, ventilation, humidity. There shouldn’t be any contamination issues, since this is a new floor. Also, each finish has a recommended spread rate which should be followed. For example, if the spread rate was 500 sq. ft. per gallon, but it was applied at the rate of 2 gallons for 500 ft., it would likely take about 3 weeks for the finish to cure enough to allow a buff and coat.

Swirls are as old as floor sanding. The floor has to be scratched between coats when using oil borne finishes to attain adhesion of the coats of finish. With water borne, usually only a single buffing is needed after the first coat to knock off grain raise, since these finishes bond chemically when applied with a certain time frame. A maroon pad is all that is needed to buff this finish. The finer the abrasive the less likely these scratches will show. I would suggest using a maroon pad with sand paper strips no rougher than 180 grit. But since this finish appears to be too soft at present, I would leave it for a month and give it another go then. but I have no idea what the yellow stain is. That would lead me to think the finish is water borne. If these finishes are applied to heavily, it can turn yellow in those areas.
I hope this gives you some answers.