Air Temperature Requirements for Conversion Varnish Curing

Cool temperatures can cause problems with conversion varnishes. February 12, 2010

Question
Are all CV's the same requiring upper 60's to cure properly? How long must that temp be maintained? Besides pot life and adding catalyst, is there anything else I need to know about CV, (as I have been using nitro for years)? Are there any differences among brands other than price? (Finishing oak for restaurant with airless).

Forum Responses
(Finishing Forum)
From contributor B:
Upper 60's temp is ideal, but I've used CV's anywhere from 40's-90's and I've never had a problem. Main difference between lacquer and CV is it is harder to do touch-ups. CV is much tougher by nature so it’s harder to blend in and what not. Also, when applying multiple coats, lacquer melts into itself forming almost one thick coat. CV does not have this melt-in property, so the only form of adhesion you get is through sanding and creating scratches for the next coat to grab onto. As far as I know there is no recoat window. It must be sanded in between every coat.

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From contributor E:
I switched to MLC CV back in Jan. I used nitro for 18 years. I would never go back except for certain applications. The most important thing is watch your mil thickness. The way I was taught to use it was - spray one coat, walk away, go back 45 minutes later, sand, and shoot again. Walk away and go back an hour later and you won't believe how beautiful it is. Like I said watch the thickness.

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From contributor W:
We switched from SW to Mohawk CV about one year ago. The SW has so much formaldehyde in it, it will sting your eyes and throat when it flashes off. The Mohawk CV is formaldehyde free (and $10/gal cheaper). The SW CV is also much harder to clean up.

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From contributor R:
I haven't used the stuff in quite a few years but I had an unhappy experience due to temperature. Used it (SW brand) in a Charleston SC summer because it was specified for a particular job and loved it! Easy to spray, flowed out well and sanded freely. Yes it was nasty stuff but that is why they make respirators. I continued to use it on various products until the fall when the temp dropped a bit below 70.

The threshold was 68 if I remember correctly and at the time was not provided in the data sheet. A failure occurred as a result and I had to strip a few mahogany tops and start over- it could have been worse. Based on my experience with this product I would recommend taking the temp threshold seriously, make sure the ambient temp and the material temperature is well above the minimum.