Pigmented CV for Paint-Grade Kitchens
Conversion varnish makes a good opaque finish, but good prep and application are important. May 15, 2012
Question
We want a better finish for our paint grade jobs. We have used Valspar Valtec pc pigmented and get a lot of corners that chip, and it doesn't seem too durable. Would a CV be better for this? How do small shops deal with pot life of CV? Catalyzing in house seems like it might be a lot of waste - hard to estimate how much to mix, etc. May need less touchup, but when you do need it, how?
Forum Responses
(Finishing Forum)
From contributor C:
All CV I've used does not come pre-catalyzed, as pot life is about 8 hours. As a result you buy the CV and catalyst separately so you can mix up as little as you need. Just get a few measuring cups.
From the original questioner:
I am aware that you catalyze CV. So as not to waste much, what is the minimum you can mix up ?And what about smell - are some better than others?
From contributor B:
You guys need to call Gemini Coatings and ask for information on their 21-day pot life conversion varnish. Don't let the competitors of Gemini tell you it's just a pre-cat, it's not. Do your own testing and you'll see for yourself.
From contributor M:
I've been in the same position you are in. First of all, if you are doing painted cabinets, I would most definitely do CV as a topcoat. You will see a big difference in your finish. I used to use Mohawk CV and for the last few years have used Chemcraft and I like the Chemcraft a little better. As far as the smell, I can't tell much difference in the two. As far as pot life goes, it's just something you learn as you go. I see what all I've got to spray and mix what I think it will take. Sometimes I undershoot it and have to mix a little more to finish up with and sometimes have some leftover. Anymore we have usually got two kitchens going at once, so if I've got some leftover, I'll spray the drawers to the next kitchen until I run out. We are a small shop as well.
From contributor L:
Chipping on your corners is likely caused by too sharp of a corner. Pre-cats are softer than post-cats and tend to chip less. Try rounding your corners more. CV is a harder finish, but it is also more brittle when cured.
From contributor J:
Contributor L hit the proverbial nail. If you are having chipping problems, CV alone is not likely to solve them. I've been using Valtec in kitchens for years with no problems. Sounds like you need to pay more attention to breaking the edges in the prep sanding stage. A sharp edge holds no finish and is easier to damage than a slightly rounded edge.
I have seen endless cases of water damaged cabinets. Usually the sink cab where the door edges were never broken. Resulting light wear from use was enough to rub and chip the edges and allow water to get underneath the finish. This is rarely the fault of the finish and almost always the fault of the finisher who did the work.
From contributor I:
If I know it's going to be less than a gallon I'm about to spray, I mix as I go to avoid wasting. It's easy - just fill your cup on a scale instead of fiddling with measuring cups. The only unexpected issues I've had with conversion varnish that I was never warned about are:
- Don't sand too much between coats. If you have to sand deep to try and sand a bad spray job (texture) or a defect out, you could experience a crackling effect when you re-coat.
- Don't wait too long to recoat. After a few hours you start running the risk of getting the crackling effect. You won't see it start to happen until 10 minutes after it's been sprayed. Rule here is no more than 3 hours or wait a full 24.
From contributor M:
You bring out some good points. Scuffing too much between coats will definitely cause it to (burn) through. And I always have the best results when waiting after the 24 hours. Waiting the weekend is even better.
From contributor N:
I agree with the sharp corners. And try the Valspar Valtech Ultra - pre-cat conversion lacquer. Tough stuff with no daily pot life issue. We use the pigmented on chair frames that take quite a beating.
From the original questioner:
What makes the Valtec pre-cat conversion a conversion lac? Is it just a better pc or what?
We do break all corners a lot, and we do 90% inset. Maybe we sand too well. We sand to 180. What do most sand to on paint grade?
From contributor N:
Yes, from what I understand it is a better pre-cat. Rather than shop catalyzed, it is catalyzed prior to delivery at your distributor with a 6 month shelf life thereafter. It is a nitro/alkyd/urea resin blend like Campbell's MagnaMax, with less yellowing and a faster cure. At 26% solids (clears), somewhat heavier than a normal pre-cat - including Valspar's.
From the original questioner:
Sorry, forgot - we white wood sand to 150. Undercoater at 220, between coats (scuff, de-nib) 280.
