Finish peeling in sporadic areas

Q: The old owners refinished our floor but they are peeling, in odd and sporadic areas all over the house. Can the areas be fixed or do I have to redo all the floors?

A: I would definitely recommend a complete re-sand and finish. You are either dealing with a contamination issue between the coats of finish, or improper preparation between coats to ensure adhesion. What you apply on top of this now will only be as sound as the coatings it is sitting on, which by your comments is not stable, but peeling throughout.

Similar Q: I finished a floor in my house with Minwax stain and polyurethane and it came out great. I did a 2nd room 2 years later using same steps and same can of stuff, but the polyurethane is chipping/peeling in spots. Was the polyurethane too old? Can I fix just the little peeling spots?

A: If you applied more than one coat of finish either you didn’t buff or scratch sufficiently between coats or there was a possible contaminant on the floor. Believe it or not, but it is true, even typical vasol or mineral spirits bought at the store which one may use to clean their brushes and applicators may be recycled and contain other ingredients that are contaminants.

You could attempt to fix the spots, but I might do the entire floor again if there are many.

Related Q: I put down a first layer of oil based Minwax poly and there are white areas where it looks like it didn’t adhere. No bubbling. What’s causing this blotchiness on the first coat?

These are 100+ year old subfloor hardwoods that have never been sealed. There shouldn’t be any contaminants like waxes, etc. The floors have been covered with carpeting for decades, and they are so rough that mops or cloth would catch on every grain. It’s very uneven, splintery flooring (staining was painful!) I sanded with a drum sander, and then hand sanded all the areas where the drum wouldn’t dip low enough to reach in the grains. I used a roller and a brush simultaneously because the roller wouldn’t dip low enough to hit low grains.

A: Really difficult to say. Is it peeling in those spots? Given the dips you mention, is it possible you were not able to sand those spots also to clean wood? They were covered for years but who knows what chemicals were used on that carpet to ‘clean’ it over the years? And if there is no finish on the wood it will absorb whatever was used. I sanded and stained an oak floor last year. There was one small area that had a water stain. After my initial sanding the owner, a contractor decided to try oxalic acid on the spot rather than change the boards. This was no problem in and of itself. However, he got the idea to neutralize the acid with a very soapy solution of water and dish detergent. I sanded the entire floor two more times after all this and stained the wood. Everything looked great until I started applying the polyurethane. In the area where he used soap on bare wood the finish was repelled and would not stick. The only answer to it is probably to replace the affected boards but I think he just decided to live with it. I use this as an example of how certain substances can penetrate into raw wood and then be difficult to impossible to remove.