Q: We recently put down beautiful unfinished Brazilian walnut hardwood floors. It has been almost a week since the first coat of the poly was put on and it just doesn’t seem to be drying. After doing a bit of research on the web, I have come across a few places that say an oil based poly on Brazilian hardwood is not a good idea; it causes problems like we’re seeing.
Unfortunately, I have not found any solutions! Where do we go from here?
A: As these types of woods become more common in North American, we are going to have to bump up our learning. I have not dealt with Brazilian walnut, but like many others is likely quite oily. I would have suggested applying a universal sealer (shellac based product) to seal the oil in, or apply a couple of coats of penetrating oil such as Waterlox first. I have also learned that wiping such a floor down with lacquer thinner will kill the resins long enough to get a first coat on. I would ventilate the area well and get a high velocity fan blowing on the floor. If possible, a bit of extra warmth will help. The last time I finished an oily wood, I applied a couple of coats of penetrating oil which did a good job of blocking the natural resins in the wood. Then I applied poly on top.
Follow-up Q: We actually went ahead and stripped as the more research we did, it may never dry! We bought a water based poly as the oil based caused problems because the Brazilian wood is oily like you said and resisted it.
When applying a water based poly, do you sand between coats?
A: All water borne finishes I have known will chemically bond if each coat is applied within a certain number of hours of the previous. Each one is a bit different, and you have to go by the manufacturers directions. It is not uncommon to do a light buff after the first or second coat just to smooth it. since water borne finishes do not provide as heavy a film, being lower solids, this must be done carefully and gently.