Pin holes in filler after finishing

Q: When a flooring company finished our Brazilian Walnut floors, they used a sandable wood filler in the hairline cracks that had appeared between the planks when the wood shrunk somewhat after installation. They filled the cracks several times with a sandable wood filler but after each sanding, some of the filler came out.

After 3 coats of urethane we were left with thousands of pinholes which the urethane made really noticeable. It looked so bad, we had a second floor company start over. They sanded back to the bare wood, after another 3 weeks and 4 more coats of urethane we are left with the same problem. Each coat of urethane built up higher around the holes and made them stand out. We have lost weeks of construction time and thousands of dollars to the floor re-finishers.

It looks so awful, we are considering using the walnut as sub-flooring and laying a prefinished floor over it. Could we use a floor putty to somehow plug the holes and THEN have another coat urethane applied over top? My husband thinks one or possibly 2 coats of urethane would level out over the holes if they are filled first. If its worth a try, should the floors be burnished first, then filled with putty? The color putty jar says to apply a coat of oil based urethane over the putty so I assume the dull waxy film left around the fill hole won’t cause a problem with the urethane adhering? Or do you fill first then burnish or fill and clean with a solvent?

A: Perhaps you can avoid anything more than a touch up with the right product and colour. My supplier in Toronto carries tubes of color-rite, which comes in hundreds of colours and the residue wipes off easily with a damp cloth.

Bona Kemi also makes wood fillers that can be tinted.. Pacific Wood Filler it is called. Woodwise also makes jars of wood putty for pre finished or already finished floors. I am not sure if you would get a colour to match your floor or if you can further tint them. Another filler worth checking out, boast it will not shrink, crack of fall out! that would be a first! check them out at They do have a U.S. distributor, and I know if you send them an email they will respond back. You will probably hear from Barry Gork. any of these products can be applied, with the residue removed with a damp cloth. However, at least Timbermate will need a finish applied over top.

I hope this helps. I don’t think your walnut floors deserve to be used as a sub floor, and to tell you the truth, I have significant issues with pre finished floors.