Troubleshooting Cracking Precat
Pre-catalyzed finishes can have problems with brittle failure, cracking, and crazing (especially some of the early formulations). The only fix is to strip and start over. January 2, 2012
Question
I primarily build custom furniture and finish by hand, but about two years ago I built a kitchen and now am having issues with the pre-cat lacquer. Wood is maple, HVLP applied white vinyl primer, wipe-on Van Dyke Brown glaze, HVLP applied SW Pre-cat lacquer. I did the finishing outdoors due to lack of a proper spray booth.
From what I have read, I believe either my dry mils are too thick or it was too cold for proper drying. The finish now has cracks in multiple areas (concentrated where it gets the most use near knobs, etc). Cracks started showing up a couple months after install.
Is there anything I can wipe on to blend the cracks together with the rest of the lacquer? Behlen's Qualarenu says it works for lacquer, but I'm not sure if that just means nitro, not pre-cat.
Forum Responses
(Finishing Forum)
From contributor E:
Call the SW tech line. When I used their stuff, they were always helpful.
From contributor M:
Did you catalyze the vinyl paint? How many coats did you apply?
From the original questioner:
I don't recall catalyzing the white primer. I don't remember it needing it though. I used 2 or 3 coats. The white pigment seems to be doing fine. It's the clear coat that is cracking. Possibly some mineral spirits residue from wiping the glaze is causing the cracks? At any rate, a potential solution is more urgent than a what to do different next time diagnosis. Like I said, I don't do much spraying at all.
From contributor J:
The problem is simple. It's the product that's junk. I have had the exact same issue with the exact same system. We solved it by recoating the entire project with a compatible conversion varnish from Gemini. The next step in the failure will be the pigmented coat starting to crack and then flake off at the joints and end grain. Consider yourself lucky that you can fix it before it's a total failure.
From contributor O:
I've seen and had to deal with this problem many times when pre-cats were something new. Nothing less than stripping down and refinishing (with another brand) works well in the long run. Seems some brands have either curing brittleness problems, or if you spray over an already dried pre-cat, this can shock the previous coating, causing cracking and crazing.
From the original questioner:
Well that is disheartening. Is there anything that you can recommend to correct in place? Uninstall/refinish/reinstall is not possible.
From contributor O:
The only correct way to solve this problem is to strip and re-finish this job. On the pre-cats, in the directions it states that re-coating or respraying should be done between (I'm guessing here) 24 hours of the first coat going on. It might even be 8-10 hours. It will also state that additional coats could be applied after full cure is reached (1 week thereabouts).
I've been down that road so many times that I hate certain brands of pre-cat. The shock of the higher flash solvents just basically shatters the cured coating underneath when a second coat is applied outside of these specs. There is no remelting the finish to remove the cracks - you wind up with a sticky fuzz filled mess. Best to go with a post catalyzed coating.
I hate to say it, but reducing the VOCs of our coatings forces the manufacturers to rely on acetone based systems and they are pretty limited in adding anything else to aid in flow or dry time or the use of plasticizers that keeps the coating pliable. Our pre-cats are curing like plate glass and it sucks.
From contributor W:
If I read the problem correctly, you applied heavily around the door knobs, etc., with regular application elsewhere. Now the area that you sprayed excessively is what's cracking. Is this correct? That area exceeds the dry film thickness for that pre-cat topcoat. It's gonna crack. Nothing you can do except strip it off and reapply topcoat.
