Hi - I'm a hobby woodworker/finisher and know a thing or two about top coats. But I don't know floors.

My contractor just installed oak stair treads in my house...I asked him to use a water based poly so the stairs would match the rest of the house, which recently had the 80-year old oak floors refinished by a floor contractor - and they used a water based poly over a dark brown stain. Floors look great.

But the stair guy used Deft Brushing Lacquer, he wiped it on over the same stain the flooring guys used. I couldn't believe it when I saw it. I have used that in the spray can for touch ups on lacquered stuff - I'm used to spraying nitro on guitars and other wood projects but would never have though of it for floors. Deft even says on the can - "do not use on floors." I called them and they do not recommend it saying it is too soft for floors.

My contractor is good at a great many things and he has done numerous projects small and large over the last 2 years on my house and I trust him. He says he has used the Deft before, and that floor guys he knows recommend it as it is more durable than other clear coats and "won't scratch like poly." But that flies against everything I know about top coats. I also worry about yellowing over time which my water-based poly floors won't do. The stairs don't get a ton of sun, but do get some.

Any advice? I can leave it, I can try to chemically remove it, I can shellac over it and and poly over that, I can make him sand it back and start over. All feel like bad options...

Thanks!

Deft will not cure for a couple of weeks. Water-based poly-urethane will stick pretty well to any cured finish. Oil based poly may not stick if any stearates were in the Deft to help with clogging of the sandpaper during prep for the next coat..
Deft says that it won't yellow and water-based poly will not yellow either, but wood will amber when exposed to light over time.
You can do an adhesion test on one end of a tread by cross hatching with a razor blade then pressing packing tape into the sample and if any of the finish comes off when the tape is removed you will have an adhesion problem.
Two more coats of Deft with scuffing in between coats will last for a long time

Thank you! But will the Deft wear poorly? am I destined to have to keep applying it every year to keep it up?

I'm in California...I can't see nitro lacquers being available forever...so how good a long term solution is this?

I think Deft would wear better than shellac, which some use for a floor finish and then wax..
If you decide to add more than one coat of Deft it will wear good enough to completely cure so you could then apply a water-based 2 part poly-urethane.
Water based poly sticks pretty well to other cured finish. You will need to try an adhesion sample to see, but water-based poly wears very well. If you find a preferred water=based poly you may find a phone number to ask questions.