From contributor D:
I've been looking hard at waterborne coatings over the last six months. During this period of time I've concluded that there are some instances where waterborne coatings are in fact superior to solvent borne and other applications where they are fairly close to being completely useless. I will now elucidate on these.
For any application that you’re going to finish natural - no stain, no shading, no glazing, no toning - just shoot the sealer and topcoats onto the bare wood and go, waterborne is perfect. Garage cabinets are an excellent example. I've blown ten gallons of waterborne on my pal's shop cabinets in the last two weeks and they look great. The best waterborne materials perform quite well and I think probably are just as tough and resilient as our favorite lacquer, pre-cat and conversion varnish finishes.
The one application where they are the only way to go is drawers. I’ll never finish a drawer again with anything else. There is no smell that lasts for years as there is with lacquer and since you can wipe most waterbornes, they are clearly the most efficient way to finish drawers, using a method I’ll detail now.
I invented this method because I had bought a five gallon bucket of a waterborne urethane that I didn’t like because it took a month to reach acceptable hardness to me. I didn’t want to throw away $150 worth of paint but I didn’t want to shoot my bookcases and then wait a month prior to loading them with books either. What I did was buy five sheets of Finish birch (great stuff compared to the typically crappy boat patch ridden delaminating Baltic birch) and shoot this material with the offending waterborne urethane. Since I wasn’t going to cut it up into drawers anytime soon, I just shot it and let is sit in my sheet goods rack for a couple of months until I needed it.
When that day finally came I cut it up and dovetailed the joints. Finish birch does dovetails a lot better than Baltic birch since the pins cut cleanly with no delaminating, as is common with Baltic birch. I also cut the bottoms from pre-coated material as well. After glue up, made easier by the pre-finishing, I was left with unfinished edges upon which I simply wiped the urethane to seal and coat. In no time flat a finished drawer.
Where waterbornes suck is where you need to use the entire finishing tool kit. Waterborne stains vary from decent to unbelievably bad. They are affected by your local climactic conditions (for example, I live in a desert) and they raise the grain, which you need to figure out how to sand off without sanding off the stain, and this is something I’ve found hard to do. Waterborne glazes are worse, with little if any open time, and shading and toning with waterborne isn’t fun either, since you don’t know what the color really is until the coating changes from milky white to clear.
If you’re willing to wait a couple of days, and your finish manufacturer permits you to, putting waterborne sealers and topcoats over conventional stains can result in a very nice finish with minor grain raise, since the stain has sealed the wood. I’ve used General Finishes Pro Series Acrylic Lacquer (one of my favorites) over their Prelude stains after waiting three days for the Prelude to dry and the results were excellent.
So there you have it. No stain stuff is a waterborne slam dunk. Stained stuff with plenty of time to wait for the oil stain to dry waterborne is an excellent possibility. Complicated finishes with the whole nine yards, as they say in New York, forget about it.
I use a wipe-on waterbase polyurethane to act as a barrier coat over my burn-ins (stick shellac, lacquer sticks, burn-in sticks, hot melt sticks, and so on). I wipe it on, let it set up and then shoot a light coat of aerosol lacquer on top. To be on the safe side, that aerosol lacquer should be Mohawk's pre-catalyzed aerosol lacquer, because it has a blend of solvents that are weak enough to not attack the waterbase barrier coat, yet superb enough to allow for excellent flow out of the Mohawk aerosol pre-cat. So here's a little touch-up tip using both waterborne and solvent systems to get the job done.
I forgot to mention, what's the issue with burn-ins and barrier coats? The burn-in material (a mixture of resins specially formulated to be made molten and dripped into dents, small depressions and compression damages) wants to gloss through any topcoat. That sheen difference bothers the owners of the pieces of furniture that I have to touch up. Hence, there is a need to create a barrier over the burn-in so that the topcoat sheen of the repaired damage will have the same degree of gloss as the original surrounding surface sheen.
Contributor S, the Pro series is not on their web site. Call up General Finishes and they'll give you the inside scoop. Good stuff. The Pro Finish Acrylic is a waterborne. I use the oil Prelude, allow it to dry for a couple of days, then go right over it with the Pro Series Acrylic. No problem with the tape test yet.
Where did I say that they were non-functional with oil stains and lacquer based toners? I stated that I don't like waterborne stains or waterborne toners and that I, in fact, use Prelude (which is oil based under the GF Waterborne Acrylic). The exact quote taken from my posting above: "If you’re willing to wait a couple of days, and your finish manufacturer permits you to, putting waterborne sealers and topcoats over conventional stains can result in a very nice finish with minor grain raise since the stain has sealed the wood. I’ve used General Finishes Pro Series Acrylic Lacquer (one of my favorites) over their Prelude stains after waiting three days for the Prelude to dry and the results were excellent."
The development of water-based stains has taken a very positive turn over the past 2-3 years. General Finishes manufactures an excellent line of WB stains that are showing very workable open times. Also, Fuhr International continues to develop a full line of stains that has shown a marked improvement over the past few developmental cycles. These companies successfully sell their systems into both OEM and refinishing applications. Grain raising has been greatly controlled by the use of low water-content blends and the open times can be controlled with the use of slow WB co-solvents. Another firm, Golden Paints, is marketing a WB glaze which offers the best open-time that I have tested to date. With the help of a special retarder, my own use has shown that the Golden glaze is as equally functional as any solvent system. The key to the success of these new generation WB stains and glazes is the need to adapt and fine-tune the method of application. My concern is that you generalized that all WB stains don't cut it.
Also, contributor B, the Lockwood water stains will work very well for your sapwood sprayed with an airbrush or an automotive detail gun. Just make sure to let dry completely before sealing. In Reno that takes about an hour. If you're not sure, use a moisture meter to check or just leave overnight if you have the time. I have not used the Homewood stains but I read here that they work well also.
Contributor R, I also think the problem is somewhat easier with water dyes, as they have no body and penetrate much deeper into the wood. The pre-grain raise is desirable, but not in my experience mandatory, as you can shoot a clear coat over them, lock in the grain raise and still have enough color on and in the wood to sand off the raised grain with a sanding sponge and carry on. With waterborne wiping stains (once again the main object of my discussion), there is an acrylic binder which makes them lie completely on the surface. There is little room to sand off the raised grain without cutting through them. True pre-grain raising would help, but the idea here is a one-for-one replacement for a solvent system without the additional steps. Water dyes are great. I've used them but prefer to spray alcohol dyes myself. No problem.
