I wish I had a nickel for every time I have heard those words either as a rhetorical question or a bold statement of fact. In the 21st Century when lacquer coatings are very high tech, the answer is almost always a resounding no. But before we can understand why this statement is not true, we need to look at this “chemical stew” known as lacquer thinner and understand what makes it what it is. Then we can understand what makes it work the way it does.
Yes, those liquids described as lacquer thinner are made up of a number of different chemicals. Those chemicals fall into two broad categories; diluent solvents and active solvents. Both have a function that is described by their name. Diluent solvents are there to dilute the nitrocellulose and/or resins. To illustrate why dilution is important, nitrocellulose, as it arrives from the manufacturer, resembles a barrel of the lint that comes out of your clothes dryer. The diluent turns that into a liquid. Active solvents are there to actively help that liquefied combination move from the spray tip to its “forever home” and get it to lay down into a glass smooth film.
Let’s examine what’s in a pail of lacquer. It contains two things; volatiles and volume solids. The volume solids (the nitrocellulose and/or resins) are what you pay for. Yes, you pay for the volatiles too but understand that by the time that coating is sprayed out and cured, all of those volatiles have flashed off into the atmosphere. All that you have left on the surface after the lacquer has cured are the volume solids. As volatiles, the diluents and actives have gone away and the resins remain.
These 21st century resins and coatings are wonderful in what they can achieve for us. Yet, they also demand respect. When you open a brand new pail of lacquer, I can assure you that the manufacturer has mixed the proper solvents (the volatiles) in with the volume solids (the film-forming resins) to keep all those molecules in that pail as happy as possible and ready to do their job for you. You can also be assured that their lacquer thinners are designed to work the best with their resin packages.
But the journey from the pail to cured coating is a difficult and sometimes perilous one. Along the way, that coating is exposed to temperature, humidity, air flow, differences in spray equipment, and differences in the sprayer’s gun technique. Then too, let’s not forget that lacquer is often affected by the surface it is applied to. Is it an oily wood, solid wood, veneer, stained surface, dyed surface, sealed surface, scuffed surface, etc? As you can see, it might not take much to make that coating wish it was still back in its pail.
One thing that is true in almost all of those cases, there is a chemical cause or effect to each of those issues. Some may compel us to add a little “lacquer thinner” to the mix to overcome the effects of a hot day, a lot of airflow over the surface, or a gun that doesn’t atomize well. (Look for Part II in next's Friday's blog.)
Until next time…spray on!!!
Bernie Bottens writes and teaches on the subject of wood finishing in industrial woodworking. Based in Vancouver, WA, he teaches wood finishing to shop owners, shop foremen, spray technicians and finishers all over the Pacific Northwest. Bernie is the owner of Kapellmeister Enterprises Inc. He can be reached at firstname.lastname@example.org.
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