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The Beauty of Waterborne Finishes

Jun 25, 2016 | Expert's Corner | 0 comments

It’s a rare finishing class that I don’t get someone who has been a die-hard user of solvents, such as lacquer, conversion varnish and the like, who is reluctant to try waterborne. There is certainly nothing wrong with those finishes, after all they have been around for years and have stood the test of time.

Waterborne finishes are the new kid on the block, right? Well sort of. Ever used latex paint, either interior or exterior? Well, that is basically a waterborne finish and it too has stood the test of time. Now, thanks to some creative chemistry we have waterborne coatings for furniture, automotive and just about every application known and it is just going to keep growing, as it should, it is great!

There is a slight learning curve if you’re an old solvent user, but not a difficult one. I know because I have used solvent based products since I was thirteen in both the auto body and furniture worlds. First time I tried a waterborne, well, it wasn’t good; but I was determined to master it. What follows is a synopsis of my journey.

The first thing I noticed was that despite my best efforts, the finish got runs, I just couldn’t get past them. I also had a lot of orange peel. It was frustrating. I was doing everything that I had read or been told, had a nice big 2.0 needle/nozzle, but it was like spraying with a water hose. I wasn’t happy.

Then I started playing with smaller needle/nozzle setups and reduced the fluid – what a difference! I found that using a 1.4 or 1.5 needle/nozzle and backing off the fluid, I could get a much better finish. Then I started to pay attention to the initial texture on the surface directly from the gun versus what I had a few minutes later. This brought to my attention that because of water’s surface tension, it wasn’t laying out quite as smooth initially. Unlike the solvent-based products I had always used, it took a little bit of time for the finish to flow out and lay down. Allowing this time allowed the finish to lay down nicely. Over the years, the flow out of waterborne top coats has improved, and while they still don’t lay out the same as a solvent base off the gun, they come close.

Then came my next issue, overspray. Unlike solvent-based products that dissolve back into themselves, water borne isn’t quite the same. The overspray tends to lay on the surface more. The solution, however, is simple. Reduce the overspray and get a nice wet coat on as soon as possible. Don’t give surfaces time to tack up while there is overspray being produced. Initially, I overcame this by spraying fewer pieces and by positioning them in my booth so that overspray being pulled by the exhaust fan wasn’t pulling overspray to another surface. This worked pretty well but I make a living doing woodwork and finishing so the reduced number of pieces in the booth and added time were just not acceptable. I knew the answer was in finding some way to increase the fluid and still atomize the finish so I could ‘move’ more pieces at a time.

I was using gravity fed spray guns and also had tried some of the turbines and they were okay. With the gravity fed guns I had to increase the air pressure, thus more overspray; or reduce the fluid and in some cases both. The turbines were 2-stage and I couldn’t increase the pressure so I had to reduce the fluid, again I was restricted. That’s when I realized that if I could get the fluid under some pressure, like a latex pump sprayer, I could get what I wanted. With my gravity fed/compressed air guns I noticed a significant difference if I used one of the bigger cups on top and the cup was full. Just the added pressure of the fluid helped, so I got to playing with “drilling” and trying to rig up the gravity feeds so I could pressurize the cup, not with great success, but I had enough success to know it was the answer.

If you prefer using a gravity fed spray gun, I have found that the 3M PPS system is superb. Soon after, I got my hands on the Apollo Atomizer, my troubles were over. I often run mine on compressed air, but I also have the 1050VR Turbine. I can get on cruise control and knock it out. I typically run the 1.3 needle/nozzle because I can get the fluid to the gun and cut the pressure down so there’s very little overspray. Now, the booth gets loaded up and I’m back to “in and out.” There is one down side to this, I teach finishing classes and when the Apollo is cookin’ they complain because they don’t get much spray time. They get over it when they see the finish they get. Just a couple of more things I tell my students. The first is about the viscosity. It has improved in the waterborne finishes so here is the test I use, very simple. If it will go through a medium mesh strainer as fast as you reasonably pour it in, you are good to go. Secondly, when you spray a waterborne, look across your panel, you want to see a fine, light texture if any. Look for the whitish haze (waterborne looks like milk). The white haze lets you know you’re ‘wet enough’. If you have both, give it five minutes and you will see how nicely it levels out.

If you take a little time and use the proper equipment, you will find that you also can lay out a super slick finish using the new waterborne topcoats. The advantages of waterborne finishes are huge. Waterborne finishes are not flammable and are not as toxic as solvent- based finishes. Better for your health and safety not to mention the reduced insurance rates! Personally, I have found that the durability and workability are both superb.

For your next project, give waterborne topcoats a try. Happy finishing!