This week’s question comes from Larry. He writes:
I just purchased an Earlex Spray station 5000 and I’m very pleased with its performance thus far. I’ve sprayed shellac, water based dye, and Deft brushing lacquer, all with good results. I woulsd like to get into spraying more lacquer because its looks great and dries fast, but all the options out there are confusing to someone new to spraying, like me. Post-catalyzed, Pre-catalyzed, nitrocellulose, water-borne. What are the differences and what should I start with? Do certain types work better/worse in different climates? Are any brands better than others? Sherwin Williams seems to have a wide selection, and they have stores everywhere. Any help would be greatly appreciated. Thanks for your wonderful website.
And here was my reply:
Hi Larry. I know it can all be pretty confusing. There are so many options and so much jargon that it will make your head spin. I recommend reading a good finishing book by Jewitt or Flexner. These books will review all the the standard finishes and give you a more in depth review on the pros/cons of each finish. But I will give you a nutshell explanation. Waterborne lacquer is a whole different animal and will not behave like the other products. So we’ll leave that for another conversation. Think of the lacquers as having three basic classes: nitrocellulose, CAB-Acrylic, and Catalyzed.
The nitrocellulose is pretty much your “everyday” lacquer. Its the stuff sold at Home Depot and Lowes (Deft). It makes for a beautiful finish and its relatively inexpensive. Problem is that it tends to yellow over time. So its not really the best option for light colored woods.
CAB-Acrylic lacquers are made with acrylic resins and they dry “water white”, meaning they will not yellow over time. These are reasonably durable finishes that are a pleasure to work with.
Catalyzed lacquers consist of both pre- and post-catalyzed versions. Instead of curing by the evaporation of a solvent only, they also cure chemically. The catalyst can be added ahead of time (pre-catalyzed), or in your shop (post-catalyzed). Both have a limited shelf life as a result. The finish, however, is very durable as a result of the chemical curing process. I like Sherwin Williams products and I actually use them for nearly all of my lacquer. I’m not sure if its available in your area, but you should see if you can get the Pre-cat CAB Acrylic lacquer. It was relatively new at the time I was using it and not everyone could get it. But its kind of the best of both worlds: durable, water white, less toxic off-gassing, etc…
As far as conditions go, lacquers are not as forgiving as other wood finishes. Moisture and cold are your enemies. I don’t like to spray much lower than 70F, and humidity isn’t much of an issue here in AZ. But if its a humid day, forget about spraying lacquer. You can easily end up with “blushing” (moisture trapped in the finish). And keep in mind there are going to be some days or seasons (depending on your region), that you just will NOT be able to spray.
And as far as which one to use, that’s a subjective call. Nitrocellulose is relatively inexpensive and widely available. But in my opinion, its worth the trip to Sherwin Williams to get their CAB-Acrylic and pre-cat CAB-Acrylic stuff. Of course there are many other high quality brands out there, but Sherwin Williams is the only one I have extensive experience with.
For some extra reading, here are a few good articles covering the topic of lacquers. They will go into more depth than I have here.