Waterborne Versus Non-UV Coatings
August 27, 2015 | 1:46 pm CDT
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It’s funny how one thing leads to another. There I was; sitting on the shuttle bus anticipating a ride back to the hotel from the AWFS site in Las Vegas. Seated next to me was a fellow that I had never met before. After getting acquainted over fishing stories, we turned to the question of what we each do for a living. I found his words thought provoking.

He’s a shop owner who is at the show to explore solutions that would allow him to successfully dance with California VOC compliance, spray booths, fire suppression systems, and water-borne vs. solvent-borne finishing systems. That makes for a pretty full dance card!

After listening to him talk, it was clear that he was here in search of a silver bullet or two. In my experience, those are hard to find.

My number one reason for coming to AWFS was to find out what’s new and interesting in wood coatings and to write about that. This year, when I ask that question as I go from booth to booth, more than any other, I heard about water-borne UV cured coatings. As a side note, water-borne coatings have a certain stigma that follows them. There’s a list of reasons that are often put forth to explain why they are not popular. Those reasons may or may not be valid any more. Coating technology is making great strides. Things that were only dreamed of last year are realities today. Some of those are strides made in water-borne coatings. And, as in the past, European coatings technology seems to claim to be in the lead.

As new resins are created, advancements are made. VOC numbers keep going down. Durability keeps climbing. With regularity the clouds part and we have clears that, even with three coats applied, are clearer and less cloudy. And with UV curing, stack and pack times get really short.


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But what is my seatmate to do? He has a shop that is grandfathered in to a deal whereby he doesn’t have to have a sprinkler system in spite of its size. He told me he was debating the costs of a dry chemical suppression system for his booth vs. bringing a 4” water line in from the street to sprinkle his building. All that because he now has to have fire suppression on his booth.

He also said that he is looking into water-borne coatings to reduce his flammability, and he’s also looking at a conveyor line system to spray water-borne coatings.

I took the issue of conveyor systems to the good folks exhibiting their coatings at AWFS and I asked what is necessary to get started with water-borne UV coatings.

But before I go into that, I want to share that I also had a conversation with an exhibitor who had made the investment in a line system. Thereafter, he found that he could do more work with less manpower and less man hours by hand spraying with a non-UV cured water borne coating. Bummer! His $300,000 conveyor line sits idle.

The plusses (among several) for UV cured lines include that one can spray and walk away. The coating goes down a conveyor for a certain amount of time to flash off and begin to dry. When the conveyor brings the finish into contact with the proper light, (by the way, there are different lights for different types of coatings) the cure accelerates to completion. Then, there is a “cool down period.”

As the piece comes off the other end of the conveyor, it’s ready for the next step. If the next step is pack and wrap then that is what happens. If the next step is a trip to the sanding table for a scuff before a return to the spray section of the line, then that is the next step.

Now you understand in the briefest of detail how a conveyor system works. Next we need to talk about three different paths that my seat partner needs to decide upon because the conveyor system and light system are going to cost real money.

Yes, if you are crafty, you can find and install your own conveyor system. I am certain that you can find the lights that you need and, knowing how many feet per minute your conveyor travels and the time required to cure the coating, one can build a tunnel of one’s own to house the lights. But it’s still money…right? I’d still plan on having $300,000+ in my budget to get everything up and running. You’d want more if you want it done as a turn-key.
To my seatmate, here are the issues:
1. To UV or not to UV.
2. To sprinkle or not to sprinkle.
3. To dry chemical or to sprinkle.

There are coatings manufacturers that make water-borne coatings that work well without UV. I encourage everyone to do their homework and test spray as many as possible to decide for oneself. That will decide the issue of conveyor line or no conveyor line.

Would I invest in that sprinkler system? Heck yes. A fire in any part of your building will bring the potential for total disaster. We’ve all read about and heard about how disastrous a fire can be in a cabinet shop. The sprinklers may well save the day, the shop, and untold heartache, headache, and dollars. Dry chemical suppression for the booth is expensive. But again, it may save the day. But I’d sprinkle the building first unless the local fire codes require dry chemical in addition to the sprinklers.

Back to non-UV water-bornes. A conveyor here isn’t such a bad idea either. You could create a “tunnel of love” where the pieces go through a tunnel with fans to increase the circulation and increase the dry time. Remember…it’s water. Water dries slower than solvents and is heavily dependent upon humidity, temperature, and air flow.

As long as it’s warm in the shop, the air flow tunnel will help a great deal. Not so much for a shop in Minnesota in the middle of the winter unless the shop is well heated and insulated. I know what it was like to spray in my Oregon shop in the winter with no heat and no insulation. Remember… humidity, temperature, and air flow are the key words.

A shop in a very humid area of the country will have a slower cure rate than one in Phoenix, AZ in the summer. In Northwest Oregon in the winter an unheated shop will give you a quick two strikes because it’s both cold and humid there. I learned that the hard way.

I hope now that you can see that humidity, temperature, and air flow are the three helpers or hinderers to water-borne drying. If you can control those things then you should do well. I’ve given you a very brief glimpse at both UV and non-UV processes. In the near future I hope to share with you a YouTube video of a working water-borne UV cure system in action. Stay tuned!

Until next time…spray on!

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About the author
Bernie Bottens

Bernie Bottens writes and teaches on the subject of wood and wood finishing in industrial woodworking. He and his wife, Carol, live in Vancouver, WA. Bernie has been teaching wood finishing to shop owners, shop foremen, spray technicians and finishers all over Oregon, southwest Washington, and northern California for the past 9 years. Prior to that, he owned his own cabinet shop. His shop credentials include apprenticing and becoming a journeyman exhibit builder. Before that he taught in the public schools for 20 years. Bernie is the owner of Kapellmeister Enterprises, Inc. and Kap Coatings Consulting.