Catalyzed Versus Uncatalyzed Lacquers

An extended discussion of the chemistry, attributes, and performance of catalyzed lacquers compared to traditional uncatalyzed nitrocellulose lacquer. April 21, 2008

What do you see as an advantage to using catalyzed lacquer? I have always used non-catalyzed lacquer.

Forum Responses
(Finishing Forum)
From contributor M:
It comes down to durability and moisture resistance. Catalyzed is way better in both of these situations.

From the original questioner:
Thanks for the answer, but doesn't cat lacquer pose a bunch of problems with mil thickness? As far as moisture, I thought that's what the vs is supposed to take care of.

From contributor C:
I'm still a believer in NC lacquer, especially the bartop grade NCs. No, they don't have the resistance of cat nitros, but you can build 20 or 30 coats of non-cat without fear of any of the problems of the cat type. Most are sold on them because of the build and quickness also as compared to NCs, but I believe in using products I don't have to worry about mil thickness, etc. Old school? Yes! Extra problems to concern myself with? No! Have not used them in years, but if someone specified it had to be nitro lacquer, would still use the standard nitro for sure. Plus, they're so much easier to repair after they have cured. There may come a day when regular nitros are no longer around to buy, but there will still be acrylics that fit the bill.

From contributor J:
Try some Magnashield from Hood Finishing. I've been using it for nearly 5 years and it's great. No recoat window. No max mil thickness. Recoat anytime. It is a pre-cat but has all of the application characteristics of NC, with the durability of a pre-cat.

From contributor C:
Sounds like a slow promoted alkyd/amino one where the amount of AA is kept small and a weak phosphorous acid is used to promote the chain reaction slowly. If that's the case, then when it eventually crosslinks, it will finally act as other cat lacquers. Do me a favor if you're able. If you have a 3 or 4 year old sample of this coating on a sample board, put a dime size drop of their lacquer thinner on it and cover and see if it's reactive, meaning does it crinkle or lift or does it just soften the material and become sticky, like a regular lacquer? Tape off and spray a coat of the same and let dry for a week or two and see if it's burned in/melted into the previous coat, or can it be pulled off with tape or scraped off with your fingernail or a knife? This will tell you if it stays as it does in the beginning. If not, that means your ease of coating and future repair or recoating will be in jeopardy. For me to switch to this new product, it would be critical to know the long term recoatability.

From the original questioner:
I'm in the same boat as you! I can't understand why so many cabinet shops go with cat lac. They get a run or some other problem, they're stripping or making new. Why bother? Use what has worked for a long time.

From contributor L:
I'm way down on the learning curve and know near nothing about NCs. I'd not heard of a bartop grade NC; I'd assumed that was an arena where only cats were used. Could you name several so I'd have a better chance of finding one to try? Will flatteners make a difference or are they only used in gloss?

From contributor C:
Behlen Bros. makes one and so does Delta Labs in Florida, and I'm sure there are others. What denotes a bartop nitro lacquer from standard nitro is mainly the use of a coconut oil alkyd resin in the formula. This non-reactive resin (meaning it will not lift or crinkle or do any other strange things) gives gloss, alcohol and water resistance and hardness to the cellulose nitrate that it does not have by itself - they also do not scratch white after thorough cure of 30 days. Many other alkyd resins are used in nitro lacquers, such as the ones used in Sherwin Williams water resistant nitros, but they are reactive and can cause as bad a problem as the cats do. Behlens was bought out by Mowhawk in the late 80's but Mohawk continued to sell the product, under the heading "high solids WW lacquer" and "high solids WW sanding sealer." For the best alcohol and water resistance it is still the best, though I find Deltas, having the same old formula, to be now just as good as theirs. For decades these were the best lacquers you could get for any woodwork. Not an opinion, but a fact, chemistry wise.

From contributor J:
I recoated a piece that was originally finished one or two years previously. A year or so later, no problems. Another coat was applied over the original finish. Hood's specs claim "recoat anytime." I've had great results and have no reason to switch to another product.

From contributor D:
Yes, Behlen's, which was bought by Mohawk, which is owned by RPM, and whose WW sanding sealers and lacquers we built reputations on because they would not scratch white, are no longer the same chemistry. But as you well know, this can not be proven as true or not because Mohawk will not let a finisher get to their chemist, unlike Seagraves, SW, Hawkeye, or others. So, my question is, on what basis do you state that Delta has the same chemical makeup as the original Behlen's? This is a sincere question - if you have clear knowledge of this, I would like to know so I can try Delta's product for myself to compare to the original characteristics of Behlen/Mohawk/RPM/Kraftfoods/Whoknowswhoiswhoanymore.

From contributor C:
I talked with their chemist on this matter when I was first told by their rep about having an alcohol-proof lacquer. Long before Mohawk bought out Behlen's, their head chemist, now retired, told me about the coconut oil alkyd resin being what gave the Qualavite gloss 100 its amazing resistance to the alcohol and water. Early seventies. Since then my study of coatings proves this out with common knowledge coatings chemistry. The chemist was also ready to tell me that his contained the same - after using it for several years in FL. I had to agree it was at least as good as Behlen's, maybe better.

From contributor K:
I switched to pre-cat Gemini about 5 kitchens ago. No comparison with the old NC lac. This stuff is pro grade, compared to the old school lac. The only trouble I have is convincing folks that I didn't buy them at a store and actually made and shot them myself. No blushing trouble, no trouble stacking parts after one hour because they don't stick together anymore. Cost about 50 bucks a kitchen more and worth every penny.

From contributor C:
Most pre-cats are fine until you have problems - then it's another story all together. Also, you cannot build a piano finish with them. The mil specs won't allow to build that much, nor do you have to worry about potlife. I can leave standard lacquer in my pot for 5 years if needed and not waste it. I can also burn in a fresh coat even if the lacquer is 30 years old, and I can also use standard thinner to quickly remove if necessary. I think pre-cats, post-cats and others have their good points also, but I have to judge on the long term consequences of their use. And I'm not in such a hurry with my finishing that I have to be concerned about my finishes sticking together from early stacking or delivery. The bartop lacquers are, performance-wise, close to a pre-cat, and that's good enough for me, but by all means continue to use your pre-cats... I have not used either for years - don't need them anymore - gone back to natural as much as possible.