Not all lacquer thinners are created equal
May 11, 2016 | 12:40 pm CDT

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With 21st Century high-tech lacquer coatings, lacquer thinner is not always lacquer thinner.

If all lacquer thinners were the same, adding a little bit more would be easy. But, it’s not. As most folks who use coatings in metropolitan southern California know, most of the solvents in regular lacquer thinner are off limits by air quality regulations.

For the rest of us, we have a whole list of solvents to choose from that are either diluent or active.  Most Californians have a very short list and as the years pass, more and more of us may find ourselves in the same boat with our California friends.

Here’s where it gets tricky. I suspect that like me, having taken and passed chemistry in high school was not a prerequisite to becoming a finisher. I know that I didn’t take chemistry and I’ll bet that most of the folks who spray probably didn’t either.  But the answers come down playing the role of smart chemist or mad chemist. Being in the second category can certainly cause harm on occasion.

Don’t worry, it’s not that tough and I wouldn’t suggest signing up for chemistry classes at the local community college yet. Just think about these simple things.

1. Stick to the solvents made by the coatings company that makes your lacquer.  They have all been tested with those coatings and I would suspect that they work well with them.
2. If you need a slower or a faster solvent, ask your coatings rep for his recommendation.  Then, take that recommendation and follow through with it.  Even the California people have options regarding slow or fast.
3. Stay away from reclaimed lacquer thinner.  You never know what is really in them and neither does the reclaimer.  Who knows what was poured into that barrel of waste solvent before it was reclaimed?  There may well be solvents in there that will make your volume solids very unhappy.
4. The same holds true for generic lacquer thinners.
5. Unhappy solids tend to turn to cottage cheese.  In other words, the wrong diluents and/or actives make the resins solidify and clump instead of dilute and liquefy.
6. On a hot day, you can add all the fast evaporating active solvent that you want but it may not help you a bit.  The solvent may well be gone before the coating hits the surface and certainly won’t be there to help the coating lie down properly and level out.  The results are such things as orange peel, over spray, or dry spray.
7. Less is more when talking about the evaporative speed of an active solvent.  Remember, lacquer thinner is a chemical stew.  Depending on the proportion of one solvent to the others determines how fast or slowly the coating lies down and dries.  Your coatings representative should have options for you to slow the coating’s dry time.

Thinner issues are one of the most common problems that finishers encounter. On one hand, it is amazing how forgiving even the highest tech coating can be. On the other hand, most times you eat bear but sometimes the bear eats you! Try to stay out of that second category. Always strive to be a smart chemist. And to that end, stay tuned for the next part of this discussion where I’ll show you how to do that.

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.