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Working with waterborne

Understanding the differences, challenges and benefits to waterborne versus solvent paint systems
Friday, May 10, 2013 - 08:09
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All of us have painted a room or two in our homes, apartments or offices. In every case, if you were painting indoors, you used a water-based paint product called acrylic latex paint. It has little or no odor, covers well and dries fairly quickly, unless it is really humid outside. When the humidity is high, a few fans strategically placed in the room usually help it dry much faster. It’s not a very complex project to paint a room, but without proper application techniques and surface preparation, the results can be less than desirable. This is a pretty simplistic explanation of painting with a water-based product, but it is accurate for both the acrylic latex paint you use in your home, and the automotive grade of water based paint.

Although it seems as if waterborne technology is a new and mysterious thing, in reality, it has been around for decades and is used in many OEM automotive painting environments. The use of water-based paint technology has been widely accepted in Europe for a long time, and has more recently found a foothold here in the U.S. because of the lower VOCs (Volatile Organic Compounds) it produces over a traditional solvent-based refinish system.

Just so there is no confusion, the base applications are the only product currently available as water-based compound. The clears are all solvent based, although most manufacturers are developing water-based clears as well. So far, these do not have the durability needed for the automotive market, but I know of one company that seems to have cracked this problem. I am certain that in the very near future; the clear coats in these systems will be available in water.

Many collision shops today are thinking about converting to a waterborne product, but are hesitant to do so because of the negative things they may have heard about its use from some industry peers. Many shop owners look at the systems like they are contagious diseases, and they stay very far away. The reason for some of this is, initially, at its introduction, waterborne products were difficult to use, had color-match problems and were very expensive. Many shops that tried these first incarnations switched back to solvent systems very quickly because of these and other issues that arose out of what may have been premature releases of the product. Once shops tried them and found they did not work well, they are understandably very hesitant to try again today.

In reality, the paint manufacturers have invested heavily in waterborne technology and have been producing better and better products consistently in recent years. The changes in the product are staggering, and as a user of a waterborne system myself in my facility, I can say with authority that they really do work well today. They are, however, not the same as using a solvent-based system, and there is absolutely a learning curve involved, for both your painters and your production staff, in using a waterborne product.

The most important thing to understand about water-based painting systems is that they require lots of air movement in order to dry properly. I didn't fully understand this principle until I began using a water-based system, but think about it like this. In any painting operation, the painted/sprayed material dries by solvent evaporation. Common sense will tell you water evaporates much more slowly than thinner or reducer. By increasing the air movement over a painted surface, the solvent will evaporate faster. When using a solvent system, humidity in the air of your spray booth has only a small effect on the drying time of the base coats. Heat will really help the solvent evaporate quickly, so even with lower air movement and higher humidity in your booth, the base will dry fairly quickly. Not so when spraying water. If your booth does not move enough air, the base will dry at a snail’s pace, slowing down production tremendously. If there is humidity in the air, it’s really a problem. Therefore, it is very important to make certain that when you switch to water, you have your spray booth tested to make sure it moves enough air.

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