Painting Over Cracking Conversion Varnish

      Finishers discuss why a kitchen CV finish would have cracked, and how to paint over it. December 10, 2007

Last year we installed a kitchen with white CV sprayed in the shop. All was good until the heat came on, and so did the dehumidifier, and with no added moisture in the air, things started moving. As a result, finish started cracking on joints. The problem is, the homeowners are older, there is no good way to re-spray with CV, and there is so much granite on the job. Brushing of the frames in place is the only way out. Doors can easily be done outside. What are the product options and schedules for refinish? Help! Great customer, good kitchen, bad luck.

Forum Responses
(Finishing Forum)
From contributor M:
Normally if the finish is cracking, it means you may have used too much catalyst. Not sure what I would do. You may be able to prime and paint the cabinets with a good alkyd paint. The doors you may be able to scuff sand and re-topcoat, but check with the manufacturer for topcoating after a year. Are they little hairline cracks over the entire surface?

From contributor W:
What kind of primer did you use? Whose CV did you use? Is it cracking, or chipping and peeling? Is it on joints alone?

From the original questioner:
Sherwin Williams primer and conversion varnish, catalyzed according to can. Problem does not lie in finish failure, but in joint movement from excessive dryness in the house. I am not sure what can be used over the CV, without using CV again.

From contributor W:
I've sanded and used pre-cat lacquer on CV that old. You probably could use a waterbased poly by Target. Why not contact them and see what Jeff recommends? But whatever you use, I would do a sample first...

From contributor G:
PPG Manor Hall Kitchen and Bath acrylic can be tinted to your color and is brushing-friendly. We used to make a couple quarts or a gallon regularly for our lacquer customers. You are going to spray the doors with whatever in your shop, or outside, correct? And you know about filling the cracks with something a bit flexible and sanding the CV thoroughly, don't you?

From contributor J:
Cracking CV is usually the result of too heavy mil thickness. Something that is very tempting to do when painting wood frame and panel doors. The primer gets laid on heavy to hide surface imperfections and fill joints. Top coats as well.

Now, I'm not saying you don't have some wood movement going on, but I would not be so quick to blame this. Wood is always going to move, and the finish has to be able to move with it. Just the simple action of opening and closing the doors puts stress on the joints, and thus the finish as well.

When CV can't move enough, it cracks, and in my experience it is almost always due to excessive mil thickness. CV is wildly popular for its durability and resistant properties, but that same hardness may make it a poor choice for coating painted frame and panel doors. Sooner or later the joints will crack - it's only a matter of time.

Unfortunately I don't have any advice on what paint to use to refinish. Anything you put over it will probably crack eventually too. Best advice for the future is, use MDF doors for painted finishes... No joints to move and crack. If you must use a wooden frame and panel door, consider a finish that has a little more flex to it.

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