Can water-based poly be thinned for wiping?

[Ladd Morse]

I've tried to read everything I can find about finishing my new white oak kitchen table purchased from an unfinished furniture store, and I'm currently thinking that after applying a light oil stain (and letting it dry for at least two days) I would like to apply multiple top coats of water-based poly as the final finish.

I get the feeling from all that I've read that there is a greater chance of not getting that "thick plastic" look if I use the "wipe" method as opposed to the brush/foam/paint pad method. I would like to use water-based poly because of fewer VOCs (I have to do the finishing in the living space of my home and it's getting cold outside) and as it's just the wife and I, we shouldn't suffer from the lesser durability than what you would get from the oil-based polys.

What I can't find, is any information on whether or not you CAN thin a water-based poly and apply via the wipe method. Lots of info on thinning oil-based poly, but nothing on water-based.

I've been leaning towards using Zar "Aqua Zar" or General Finishes "EF PolyAcrilic". I've received an email from Zar technical support and they say "don't do it". I have yet to hear back from General Finishes.

While I do like to listen to what the manufactures say about their products, I would very much like to receive advice and opinions from experienced netizens and the results of real-world experience.

[Bob N]

Speaking just for myself, I can't stand the look of water-based poly. On high wear or spill-prone pieces I use Waterlox, a tung-oil based varnish. I like the look and feel of it - very clear, not yellow or blue, nor thick and plastic either.

Bob

[Ladd Morse]

Thanks for the reply!

I'm definitely a "likes the finish inside the wood, not on top of the wood" kinda guy. But all the oil finishes I've read about require waxing as the final step and maintenance. Is that not the case with Waterlox?

[bs]

This may help - or further confuse:

S.

[Ladd Morse]

Further exploration leads me to the Target Coatings "Oxford Hybrid Super-Clear 9000 Polyurethene" which specificially states that it can be diluted 20% for wipe-on applications.

note that this product (and many others) recommend that it be applied over a sealer, especially oak. If I am NOT going for a high-gloss guitar-body finish, but just a casual kitchen table, is a sealer still recommended?

Still intrigued by the in-a-completely-different-direction Waterlox recommendation also ...

[Steve James]

Water-based poly is an emulsion in a mixture of water and organic solvents. There is a lot less organic solvent than solvent-based poly, but there is some and if you change the composition of the liquid by too much dilution you risk breaking the emulsion. In that case, the solids content separates from the solution - i.e. the stuff is ruined. I would avoid diluting unless the manufacturer says it is OK, and then don't dilute anymore than they tell you.

I've used water-based poly a lot in the winter when I have to finish inside the house. (The rest of the year I finish in the garage with some ventilation). One thing to be aware of is that because of the water the first coat really raises the grain a lot and the surface will feel very rough. You will need to sand after the first coat almost to the point that all the poly on the surface is taken off. So think of the first coat as a sealer of sorts and let it dry very well before sanding. With large pore wood like oak you may have to do pretty heavy sanding after the first two coast.

If it were me, I would use a good brush and finish the underside of the table with undiluted stuff and see if you like the results. I think the plasticy look attributed to poly is a myth. Any finish that you build that has high gloss can look plastic, not just poly. If you don't want a glossy look, use a satin formulation, or use a gloss formulation and sand with fine steel wool at the end.

[Ladd Morse]

Thanks very much for the detailed (and on-topic) answer! :-)

[Rumpty]

Typically "water based" finished are not to be thinned. Some can be brushed on just fine as is.

[B a r r y B u r k e J r .]

I agree for the most part, except for the myth. Any finish, badly applied, will look like crap. Many bad finishes seem to be Minwax polyurethanes applied 1/4" thick, because bad finishers are unaware of the better products and methods. So the plasticky look is real, but not simply due to the presence of polyurethane, just bad usage. Also, just as with stains, there ARE better brands than Minwax polyurethane.

Even the highest quality tool doesn't do the work itself!

An alternate method is to use gloss all the way to the last coat, with a satin coat last. Either way will provide more clarity than building multiple satin coats, as the flattening agents tend to cloud the finish.

Barry

[Steve James]

B a r r y B u r k e J r . replied:

By the myth of poly and the plastic look what I (mainly) meant was that this is not something unique to polyurethane. So I agree with you. You can get a crappy result with a poor product or by improper application of a good one.

For my own education, what brand of polyurethane finish do you prefer?

Steve

[B a r r y B u r k e J r .]

I like Waterlox's urethane varnish (not the same as "original" Waterlox) , Maloof's blend, or even 50% thinned Minwax, depending on the project. I wipe all of them on.

Barry