I have several questions. I am refinishing my floors myself and am now having to re-do them because of some problems that have come up. First of all I live in an apartment that was built in 1927 so needless to say the floors are old and a little creeky. I don’t know when the last time was that they were refinished but it was more that 10 years ago. The old finish was over bare unstained wood, a matte finish, was very ambered, hard as steel (almost impossible to scratch and impossible to scrape off) and was very hard to get off. Since I am unable to move out while doing this I am doing the floor in sections.
After sanding and staining the floor (to get a deeper color the stain I stained it a few times) I finished it with Minwax oil base polyurethane (it said great on floors). After a few weeks I notice that in various spots where the planks of wood butt up against each other that the finish was lifting off the wood about 1/16th of an inch at the seams. In the spots were this is happening is where the seams of the floor bend slightly as you step on them, it is not happening anywhere else nor is it happening in the center of a plank. The Minwax was not very strong because in these areas it will chip and scrape off very easily. That never happen with the old finish that was on there, how do I keep that from happening?
I then switched to using Harco moisture cure urethane to get a stronger finish. I tried using the semi-gloss without and with a retarder and no matter how much I stir it I always end up with an uneven sheen mostly at the lap marks (the lap marks being glossier). I am giving up using this stuff but I am very curious how to achieve an even sheen.
Finally, since I now have to re-do the whole apartment I would like to know which brand of oil based polyurethane you recommend using that will give me the strongest finish in semi gloss and what type of finish you think may have been on my floors before.
Your first mistake may have been that multiple stainings. Stain contains a binder agent (like glue) that may not have dried properly with this multiple application. You would have had to wait 24 hours or more between stain applications. I use a better stain brand like the Dura Seal stains when I want a really dark color. Their coffee brown is very dark and rich, and one application always does it. You also may not have waited for each coat of poly to dry, and you may not have scuff sanded thoroughly between coats. I never use the Minwax brand, and prefer the Fabulon brand heavy duty poly instead.
The dry times listed on ALL these finishes are WAY too optimistic, and I always let stains dry at least 24 hours, and wipe my hand on them to check for transfer. I also smell the stain, to see if it has lost all solvents. I BRUSH on the first coat over the Dura Seal stain carefully, and let it dry 24-48 hours. The test for finish dryness, is to screen or scuff sand and check your screen for any gummy transfer. Also smell the floor, any solvent smell and wait another day.
I would never recommend a moisture cured poly for residential use. The toxins in that finish are most awful. You are severely poisoning yourself every time you use it. It’s for industrial use only. And they will never perfect the satin flatteners in this type of finish. We only use gloss, with MC poly.
The Fabulon Brand has a very reliable satin or semi gloss finish poly that I use all the time, with great results. But I brush the finish on, I never use lamb’s wool applicators. No bubbles and a even sheen is my result. And happy and paying customers also.
So my advice for peeling finish, is to have the floor professionally sanded again and start all over with the finishes and methods I suggest. You will get a more consistent result by sanding all the floors in the house, staining all at once and finishing all at once. Store your furniture and bite the bullet, and hire a pro at least for the sanding, but you certainly can do the staining and finishing of the floor yourself.
Oh, and don’t expect any oil modified poly to cure until a month has gone by. And, very old finishes are harder due to the fact that they continue to cross link throughout their life, until they finally become brittle and crack. This takes about 40 years, so don’t worry about it. As always your Most humble servant, Joseph, the Wood Floor Doctor.