Question
I'm thinking about switching to water based finishes. Besides the health issue, what are other advantages or disadvantages? Are the finishes just as good as solvent based? I never used them, but I think it is the future and I would like to at least give it a try.
Forum Responses
(Finishing Forum)
From contributor J:
Another advantage is not having to use solvents to clean out your equipment after spraying. Just a little warm water to flush your gear and you're done. Also not having to worry about flammability is certainly a good thing. I'm not sure there is a big difference in health concerns, though, as WB finishes are still hazardous to breathe. You'll still need to have a spray booth of some sort, and use a quality mask while spraying.
As far as quality, there are so many finishes available nowadays that you should be able to find something sufficient to meet your needs. Just like with solvents there are many different finishes to accomplish different things. I use products from ML Campbell and Target Coatings and some are very good.
Take a look at the Target Coatings website, as there is a wealth of information there. Do a little research and most importantly, practice on scrap for a while before attempting to use WB on a job. It behaves a little differently than SB in my experience, so you have to get used to it.
Cons:
- Requires heat to dry fast
- Cures clower
- Not as durable in some cases
- More labour sanding
- Much harder to sell (to solvent fanatics)
Overall the WB will cost a bit more to apply, but it's easier and better for the environment. Recently all the automotive body shops in my area switched to WB and they all started advertising it. This has made a lot of the cabinet guys stop in and take a second look at my finishes. You can't tell the solvent from the WB unless they are both sprayed on the same panel. It's important to sell the WB finishes for what they are and let the consumer make the environmentally responsible choice.
Why exactly would you use a 2k on a kitchen or furniture anyway? Nitro and CV work just fine for cabinets and case goods. Target's EM9300 poly carbonate urethane works well for pigmented colours and for flat finishes at 15 degrees. Nice and smooth off the gun, good build and quite durable. If you don't have heat it takes 3-5 days to cure and if you add heat to 75F+ it cures in 72 hours or less. If you have a really good booth with heated air and an IR bake cycle, you can cure in 4-8 hours.
I use the USL pigmented to the colour I want and then clear coat with the 9300 flat for durability. The most expensive con on WB coatings is the heated air makeup in the winter. Thankfully natural gas is cheap.
If you want to spend the money on waterborne 2k urethanes, they are every bit as good as the SB 2k. This is why all the automotive stuff is 2k base coat, 2k colour coat and 2k or 3k clear coat and now all waterborne.
I'm still looking for other 2k waterbornes for wood but have yet to find anything other than chemical cure urethane epoxies (wb) for wood. Like I mentioned, in some cases the durability and chem resistance of a single component WB will not match that of a 2k like Milesi or other.
I've been spraying ML Campbell's Polystar and recently had a couple problems with durability. In particular I had a d/w panel that the finish failed on. I'm respraying it now and am going to add a topcoat of Target CV (8000 I think), but I'm concerned with how much extra time it would add to spray another type of finish on an entire kitchen.
My current schedule is Polystar primer 4-5 coats, Polystar topcoat 3-4 coats, with approximately one hour drying time between, and light sanding between the primer and finish coats. The CV has a 2 hour min for re-coating, which is a bit of a setback. Ideally I'd like to improve the quality/durability of my finish without adding too many extra labor hours.
Contributor D, you're absolutely right. I wish I could cut down on the number of coats I'm spraying. But the Polystar primer doesn't seem to hide as well as I'd like. My doors are soft maple, so there's usually not too many defects, but it still takes quite a few coats to completely hide the grain. The topcoat also doesn't have good hiding, so I make sure the primer gets it white before I move to topcoat.
To be perfectly honest, I really don't care nearly as much about the cost/quantity of the material as much as the time in labor. An extra gallon of finish worked into the cost of a kitchen vs. an extra day or more of labor is a no-brainer.
I'm now wondering if I should look for a consultant to come in and spend some time looking at my setup and technique.
Here is a test I put all waterbase finishes through. Take a polyethylene lid from a coffee can or some other top and pour about 20 mils of your favorite waterbase into it. After it is dry enough to remove without losing its shape, take it out of the lid and leave it to cure thoroughly. Depending on the coating, this may take months or longer, so don't think you're going to see the results anytime soon. At the same time, take your favorite solvent base coating and do the same thing. These results will be quicker, needless to say.
As the weeks go by, what you will start to see in the water base coating is that the film contracts and misshapes unevenly due to the unequal drying of the film and release of water. Later you will see even a clear gloss water base start to turn milky, then toward the end of the cure, it will fracture into pieces like a dinner plate that someone hit with a hammer. Only no one has touched this film. As you see these (what are referred to as unsupported films) go through these stages, and see the solvent base film stay together, you will be skeptical of the long term performance of these products compared to solvent base products - even lowly nitro or solvent acrylic coatings.
If I test a new generation of coalescent finishes that perform like solvent base coatings in all aspects - especially longevity and appearance - I will become a user. But as long as the chemistry needs glycol ethers to wet the resin particles and water for suspension, I see no long-term viability for those products now available. My opinion? Yes, but based on sound coatings chemistry. Maybe for short term maintenance coatings it will be around forever, but I will never use the present coatings on something I want to last for 20 or 30 years or even longer.
I have a thin polycarbonate film that peeled off some plastic I used to mask some windows and it's 3 coats thick at 4 mils wet (about 5 mils dry). It resembles clear plastic like a bag with about the same strength and flexibility (again, 2 years old now and still the same). You can crumple it into a ball and then unfold it all and do it again and again. Being a satin it's slightly opaque when you hold it up, but when you put it on a surface, it's clear, much like scotch tape.
I went through a lot of different testing and experimenting and am still developing new waterborne finishing techniques. I'm sure that these coatings are much more than a temporary coating for the kitchens and millwork I finish.
The other day I made a simple glaze that will work with most any WB system out there - just mixed some raw umber UTC with some water. I spray this on the panel where I want it with a detail gun, let it dry and sand off the excess with a maroon scotchbrite (works just like Amazing Glaze SB). WB finishing is different than SB, yes, but once you get used to it, the WB system is very versatile.
Case in point, the overwhelming majority of walls in our homes are painted with latex paint. It's not as durable or good looking as oil based (in my opinion anyway), but it's much more practical, quicker to apply, and cost effective compared to oil based. People realized they just don't need the extra durability oil gives and even the trimwork is moving to latex.
If I'm painting kitchen cabinetry, I just don't have the same requirements for a coating that an entry door, or an automobile, or a nuclear submarine would. I don't need the most durable product that exists; I want something that will be appropriate for the work I'm doing. For my work I find that I can get something in WB that does what I need it to do.
I do think, like many others, that WB is the product of now, not just the future. And the more the industry uses it, the more it will be improved upon and refined. Most of the solvent based products out there that people are so attached to haven't been around much longer than WB anyway. Wasn't all that long ago that shellac or oil were pretty much your only options. My guess is by the time I'm ready to retire, solvent based will be pretty much nonexistent in all but the most specialized coatings, and the WB will be much different from what we're using today. Just my opinion based on very short experience spraying both solvent and water based coatings
Most finishing shops use pre-cat lacquer and CV and do the minimum number of coats to obtain a good finish. These cabinet shops are more concerned with price than they are with VOC emissions and worker health. I used to be one of these and could finish 200 parts a day with nitro and hardly any fancy equipment.
Contributor B, you should be using a 1.4-1.8mm tip size for a conventional or HVLP gun. You can go even bigger with some coatings (2.2-2.6mm). Most manufacturers will help you with viscosity and your gun setups.
