Water-based vs. oil-based polyurethanes

      Finishers compare notes, experiences, and opinions on the comparative durability of water- and oil-based polyurethane topcoats. July 18, 2000

Question
I would like to know if water-based polyurethane is as hard a finish as oil-based poly. If so, which brands are recommended?

Forum Responses
I have heard mixed info on this, but I have recently switched to water-based poly almost exclusively. It seems the same to me, although I don't make bartops. I really like that it dries to the touch in under 10 minutes.

I have all brands and, using a brush, they all seem very close(including the el-cheapos). Hydrocote has one that "ambers" a little, like oil-based.

I usually tint the first coat of water-based poly with Trans-Tint amber liquid dye to give it some color.



There is ABSOLUTELY no comparison. I am a professional woodworker and have tried just about every waterborne out there. They are definetly not as strong as oil based, however, in low-wear areas and areas away from cleaners or liquor (bartops), they are acceptable. Also, on light or white stains, waterborne does not yellow.

If you are going to use a waterborne I recommend Varathane; it is a floor finish which does not become cloudy and seems to hold up pretty well to abrasion, but not chemicals or liquor -- like all waterbornes.



This is one topic on which I have to say something. I've had to use waterbornes since the early eighties on the West coast, before moving to the Midwest. I have used and still use a two-component waterborne that uses an aliphatic poly-isocyanate catalyst, and trust me -- this product offers durability which is very close to the two-component, solvent-based systems. In fact, it has shown better lightfastness and abrasion resistance.

There are waterbornes which are just as good as their solvent-based counterparts; what's missing is the acceptance of the users of these products, who must adjust their systems and techniques when switching to water-based products.

By the way, these high-durability, water-based polys are not products you can buy at the hardware store. At least, not yet.
Bob Niemeyer, technical advisor



Here's the problem: Most off-the-shelf, hardware-store waterborne poly is a mixture of polyurethane and acrylic resins. The acrylic resins are cheaper and handle better -- that is why they are added -- but they are less durable. However, there are some straight waterborne polys available.

Like all tools and materials, some brands are better than others. I can tell you that I have seen and have run some tests on a variety of coatings, and there are definitely waterborne polys on the market that equal the performace of their oil-based cousins. There are also some that clearly fall below the typical oil-based poly.

Another respondent made mention of cross-linked waterbornes. These typically perform on par with their equivalents, i.e., acid cats and conversion varnishes. Again, there are quality differences between brands, and some are outstanding.

For whatever reason (and there are many) the quality and endurance range of waterborne poly coatings is currently wider than that of the oil-based ones.

Incidentally, the waterborne revolution in the U.S. was led by the flooring industry, and some of the best products still come out of that sector.



The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor C:
As the previous writer points out, the waterborne polyurethane revolution was pioneered by the wood flooring industry. I would also note that the top of the line waterborne wood floor finishes cannot be bought in a retail store and I doubt they will ever be available in that location. Therefore, I would be very hesitant to use anything that came out of a box store. Waterborne finishes are much more expensive and have a high learning curve. Invariably, the complaints ususally are a result of poor application or working with waterborne finishes in the wrong parameters.

Since I live in Georgia, I am not under any pressure to use the more expensive waterborne products. However, I use nothing but waterborne products because of the exceptional durability, phenomenal drying and curing times and because they make for a much safer and healthier work environment. I feel very confident that in years to come, the question most contractors will be asking is why it took them so long to put these products in their product line. They are worth every dime you pay for them.



Comment from contributor J:
The comment about Varathane above is true. However, there are new technologies on the market that are using new cross linking resins that flow out and give you an equal hardness to oil based poly's. I recommend Deft's Waterborne clear wood finish. After using their brushing lacquer for years I found this to be a great alternative. I also like that I can spray it without thinning.



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