Conversion varnish basics

      The pros agree: conversion varnish is best for kitchen cabinets. April 20, 2001

Question
I told my Sherwin Williams rep I need a durable conversion varnish for kitchen cabinets. He said that CV was not a popular finish in my area and suggested using a vinyl sealer followed by a moisture resistant lacquer (nc?). Furthermore, he said the only CV he had would not dry clear, but would have a whitish hue. Does anyone have experience with these products?

Forum Responses
I buy it by the drum. I thin the CV 20% with lacquer thinner for the sealer coat. Then sand and reduce 10% for the topcoat. The system is cheap and will be more durable than the vinyl-lacquer system they want to sell you. Just because other guys use it doesn't make it better--just easier, since there is no pot life with lacquer.



If putting on multiple coats, build with gloss as a sealer. Then for the last coat, put on the sheen desired. CV is used by all the big manufacturers in this business. Look at a Conastoga or Merdian finished door--they both use conversion vanish. Do they look "whitish"? Almost all my work is very high end and my finish looks it. The only time I use lacquer now is on my low-end work.


Your S-W rep must be on drugs. S-W's Water White Conversion Varnish is and has been an industry standard for twenty years. It absolutely is the best choice for kitchen cabinets and vinyl sealer/lacquer topcoat isn't even a close second. Vinyl with CAB acrylic might be okay, but the CV is clearly the way to go. I disagree about using lacquer thinner with the CV. Xylene or Toluene are the recommended reducers. The above reduction percentages are pretty much right on, however.


CV is great for some applications. However, where field installation is involved and there may be extensive touch-up or field spraying, it's not such a great choice. Also, if the quality of construction is not top notch and you find yourself spraying on too many coats to fix problems, it ain't so great. (That 5 mil coating barrier is one you do not want to cross.) We use a pre-cat lacquer for standing and running trim or items with a lot of field work. For free standing furniture, CV is great.


CV is just as easy to touch up as any other finish if you know what you're doing. I would use only CV or a very good precat for kitchen cabinets. Remember that all CV and precats are not the same. Some precats will not pass all KCMA tests. Also, many CVs are blended with NCs and other resins and are not as tough as others. Please run tests before switching to a new supplier.

Bob Niemeyer, forum technical advisor



From the original questioner:
It gets pretty cold in my shop. Should that be another consideration?


Absolutely. You should not spray conversion varnish below 65 degrees F. This is very important.


From the original questioner:
My shop won't see 65 degrees F until May, and I don't have that long to wait. Would a catalyzed lacquer be a better choice?


No finish except conventional lacquer will tolerate this cold of a finish room without balking.

You should spray in a properly designed spray booth.



CV doesn't need 65 degrees to dry--it needs about 55. It will just take longer to cure. I did about 500 drawers once, and put them outside. The temperature was 38 degrees and they were fine.


The Sherwin-Williams technical data sheet in their chemical coatings catalog states: "Coating must be applied and dried at a temperature of 70F or higher to ensure acceptable coating properties." The reason for this is the activation of chemical cross-linking by the catalyst. Yes, it might appear dry, but for the coating to perform to its design specifications, the cross-linking must take place and this will not happen at lower temperatures.


I also put what's left in my hopper at the end of the day into the fridge (if I am going to use it the next day) or the freezer if it is not needed for a couple of days. It works! CVs are a ratio and temperature reaction. Change one or the other or both and the reaction stops for now. This won't work with urethane or polyesters--they must crosslink at temperature (65 or over) or you will have problems.


CV will dry in colder temperatures. But it will not have the same hardness or durability as if sprayed in a warmer climate. You could have a heated dry room.

CV is not easy to touch up. You can not spot spray with CV. It will always show. As for the whitish hue, I have not heard of this occurring.

I disagree with using gloss for sealer coats. Gloss sands terribly. Use a cat vinyl sealer for build. As for smell, I hate krystal and lenmars (lenmar products give me some serious rashes and enormous headaches) CV.

The "below 72 degree" rule applies to all cat finishes. I've had success with SW pre cat in colder temperatures. It still dries very fast, but not as hard. And I prefer CAB acrylic over Duravar in exchange of CV. Dries faster and I think it is a bit more durable (it doesn't sand as well as Duravar, though, so I always use vinyl or AC for first coats and follow with two coats of CAB).



The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
I have formulated CVs for 20+ years and agree that CV is the way to go on all kitchen cabinets. If the temperature is below 65 degrees, thin the first couple coats 20-25% with toluene. Apply thinner coats (3-4 wet mils) and they will dry and cure fine. On the next two coats thin 15-20% with xylene and again keep your coats around 4-5 wet mils. This may seem more time-consuming but the results will be great! You do not make any money if you end up refinishing the cabinets down the road.



Comment from contributor S:
Spraying any finish coat or base to that effect in a high humidity or an un-dehumidified air source will bring about a cloudy white opaque effect directly proportional to the level of humidity. This is probably were this white is coming from.


Comment from contributor B:
In Asia, CV is also referred to as acid catalyzed paint (AC). It is one of the widely used paints for US kitchen cabinet industries based on their advantages - fast dry, high durability, passing all KCMA requirements, and good yellowing resistance. The CV is very easy to use - long pot life, and good sanding property.

While PU (polyurethane) is relatively slow dry, 4-8 hours dry to sand and has poor yellowing resistance, the door will change the color, and it will tend to yellow easily. Valspar China is the CV (conversion varnish) market leader and has a good reputation for the KC export market.



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