Waterlox over poly finish?

[Frank Martin]

This is for a peruvian walnut coffee table I posted before. I have several coats of gloss polyurethane (Varathane from the big box store). The last coat did not flow really well and ultimately I am going after a high gloss, smooth surface. I am thinking about two options. Tell me what you recommend and why:
1- Scuff sand and apply poly by diluting about 1/3 using mineral spirits. I am not sure if diluted poly will flow better or would I need to do final polishing. Never polished poly before, and if I recall correctly, it does not polish well. Is that correct?

2- Sand back the last layer of poly and apply Waterlox. In the past Waterlox got me there without final polishing. My thought is, I can just do a last coat or two Waterlox and not worry about final polishing. However, not sure if I would have adhesion issues. Should I apply another coat of dewaxed shellac or not worry about it.

What do you recommend?

As a side note, I plan to go back to spraying waterborne, but this time with Target Coatings products as I had trouble with General Endurovar. Oil based is too much work...

[Rich Engelhardt]

Stick with the poly.

The Varathane I used on some floors flowed out great once I cut it back with mineral spirits.
Poly can be polished, however - the Varathane my resist polishing if it contains Aluminum oxide.

[Frank Martin]

Stick with the poly.

The Varathane I used on some floors flowed out great once I cut it back with mineral spirits.
Poly can be polished, however - the Varathane my resist polishing if it contains Aluminum oxide.

Rich, thank you for the reply. How much dud you cut Varathane with MS, 10%, 25%? Also, how can I figure out if Varathane contains aluminum oxide, don't remember seeing it on the can?

[Rich Engelhardt]

Frank,
I cut mine back about 10%.
Just play it by ear as far as how much to cut yours back. Temperature and humidity play a big part in how well materials flow out.
10% would be a good start.
Anything more than 30% though and you may be looking at an additional coat to achieve a sufficient dry film thickness.

I believe all the Varathane floor finishes contain Aluminum oxide. If it says "Floor finish" on the label, then it probably has Al oxide in it.
The problem w/the Al oxide is that it's added to help resist scuffing and scratching of the film. When you get right down to it, putting a final polish on a film is nothing more than putting progressively finer scuffs and scratches in the film.

You might take a shot at calling them and asking if what you have has Al oxide or not.
http://www.rustoleum.com/pages/help-and-support/contact-us/

The main reason I'd shy away from switching over to Waterlox @ this point is that your chances of getting a "sandwiched" finish are greatly increased.
Each different coating has different physical characteristics - as well as chemical ones - that affect the final film.
Mixing two isn't always a good idea, but, as long as one of them is pretty well known and pretty consistent, you have a decent idea of what to expect.
In this case, you have a poly (Varathane) and dewaxed shellac.
It's not the best, but, it's not a huge risk - Scott Holmes uses both as his "go to system" for floors.
If Scott recommends something, you can be pretty sure he's used it for a long time and under all sorts of conditions and not had a problem.

However - at this point, adding yet another material - Waterlox - is going to greatly increase the chances that some sort of incompatibility will creep in.
Different materials will react to heat and cold differently & expand and contract at different rates.
That may not seem like such a big deal on an inside project - - right up until the Sun shining through a window hits it and sends the temperature off the scale.
Do that daily for a few months and the finish may crack and craze.

Note though - - I said may, I didn't say it will.
I'm sure it's been done plenty of times & the results were just fine. Just be aware that this sort of thing can happen when you mix different types of finishes.

If you do make the switch to Waterlox @ this point, I believe you would be better off just scuff sanding the Varathane and skip the dewaxed shellac.

[Prashun Patel]

If it were me, I'd stick with what you started with.

The issue I have with Poly isn't that it cannot be polished; it can. It's that it looks a little plasticky when polished.

If it were me, I'd stick with the poly. Wait longer to rub it out than you normally would with Waterlox. After you've polished, if you do not like it, you can eventually put a layer or shellac and go with the Waterlox on top of it. Conventional wisdom says poly hates being on top or underneath anything including itself. However, if you wait long enough, sand and shellac, you can switch. I have done it (caveat emptor; I'm a sample size of 1.)

[Frank Martin]

Thanks guys!

About aluminum oxide in finish, can you please expand its impact on ability to polish. Is it a matter of taking longer to polish or is it that the end result will not be that good. If it is the former I can deal with that.

[Jason Roehl]

The problem with aluminum oxide is that it is extremely tough, which is why it is used as a solid in floor finishes, and...as an abrasive itself. When it's in a finish, it likes to eat sandpaper.

[Frank Martin]

I checked the finish I have and it is not the version for floors. It is labeled as "for interiors", so I think I am good as far as aluminum oxide goes. I will put another couple coats of poly and then plan to polish in about a month.