What to Do When You Forget the Catalyst
Is there any quick fix when you suddenly realize that you're spraying conversion varnish but you forgot to mix in the catalyst? Yes, but ... February 2, 2011
Question
Not a good way to start the day. I built four interior doors and planned to shoot one coat vinyl sealer followed by two coats ML Campbell Krystall. Unfortunately I answered the phone and came back and poured the CV instead of the sealer in the pot, with no catalyst. I ran out of material at the start of the fourth door, and realized what I had done. I immediately mixed the proper amount of catalyst with an equal amount of thinner and resprayed everything, and ran out at about the same point, so I know I got it pretty evenly dispersed. The doors were still tacky when I sprayed. Any ideas as to my chances of success?
Forum Responses
(Finishing Forum)
From contributor U:
This will fail. The catalyst is a major component of the post cat product's ability to crosslink and provide chemical and moisture resistance and durability. It will never lose the tacky feeling, though it will dry on the surface to a small degree. Expect to be called back to refinish them in the future if you don't strip and refinish now. Spraying anything on top of them as they are now will cause wrinkling and major adhesion issues. It's a tough spot to be in, but the only way to go is the right way.
From contributor C:
When you realize you made a mistake like this, you really have to pause for a second and think through all of your options. Your objective at this point is to minimize the pain of wasted labor/man hours. By shooting catalyzed material, you only dug a deeper hole. That CV must be stripped - the sooner, the better.
From contributor L:
Been there, done that... sucks. Strip it, do it over again.
From the original questioner:
I let it sit overnight. The adding of the catalyst did help it dry. Now it comes off pretty easy with a cabinet scraper. About 1 1/2 hour each door to manually strip and resand ready for stain. My newest shop accessory is an orange day-glo spray can, which I used to put an X on every lid of cat finish I have. Why, oh why, doesn't Campbell use different colored lids for their cat finishes? The label on my can must have peeled off sometime. Also, note to self: next lifetime, get a job where you get paid even when you screw up. Banking or perhaps the medical field looks promising.
From contributor B:
I sprayed four decorative corbels with un-catalyzed ML Krystal, and realized within 4-5 minutes what had happened. I called around like I needed an ambulance, finally spoke, I believe, to the tech guy at ML, and was told to immediately mix up some Krystal, properly catalyzed, and spray. What did I have to lose? No perceivable adhesion issues. That was two years ago. I see the job regularly, and there is no difference that I can see between those four and the other 2-3 corbels. I am absolutely committed to quality and I wouldn't necessarily do this on a major bank of doors, but it worked that time very well.
From contributor D:
Instead of shooting fresh catalyzed product on top of the uncatalyzed product, put on a fresh coat of slightly over-catalyzed product. With MLC you add 10% catalyst. In this situation, go for 12% catalyst. You need your new coat to kick the tacky coat so that both catalyze.
From contributor B:
Contributor D, even better - I agree.
From contributor U:
I don't see how that remedy would work. The crosslinking of the post cat products begins when part A (lacquer) is introduced to part B (catalyst). These have to be blended together either by a shaker or stirring. Just spraying a catalyst or catalyzed product, or even over-catalyzed product on top will not achieve blending. I think some of the catalyst might bite into the surface of the un-cat product, but there is no way it will complete the crosslinking all the way through. I don't mean to sound negative, but I don't know if this is a tried and true solution someone else should follow. Also, the intercoat sanding can get you right back down into the material that didn't cross link, and I guarantee the follow up coat will wrinkle. It's the nature of the beast on post-cats.
From Paul Snyder, forum technical advisor:
I've been in the same situation before and the chemist at the tech help line recommended topcoating the un-catalyzed finish with a coat of normally catalyzed finish. It worked very well, as contributor B said.
The chemist said *do not overcatalyze* the second coat.
That job went out over five years ago and I've never heard a single complaint from the customer. There was a half day delay between the first and second coats.
From contributor B:
I just was over at the house where this took place today. When I'm over there again, I'm going to do a little scratching in an inconspicuous place. Then I'll feel like I have the definitive answer. As far as coloring and sheen, they all seem to match well.
From contributor J:
In the past there was a great discussion about CV turning color after 6 to 9 months. Many were trying to determine what the cause of the problem was in a perfectly fine appearing finish. If I remember correctly, they thought overcatalyzation was the source. If that's true, your fix could have a lifespan of 6 to 9 months.
From contributor B:
For me, it's been two years and running. The kitchen is in cherry and seems to look the same as the rest, but it's certainly not a white kitchen.
I deferred too quickly regarding the overcatalyzing the second coat. Overcatalyzing that coat is just that - overcatalyzing, which will lead to problems. Forgive me for remembering this two days into my participation in this thread, but now I remember the conversation with the tech better. They said, catalyze the top layer and recoat. I asked, should I add a little extra? The answer was no - overcatalyzation is overcatalyzation. I must add, I'm pretty sure that there was the typical, "We cannot recommend this procedure, but some people have tried this." Not a shining endorsement, but I'd still use it in the small application that I referred to, with my under countertop carved corbels.
On a positive note, those of us who've done this before have (or should have) a pretty healthy fear of ever doing it again, which will help us be more attentive when we're mixing up finishes in the future. I pause often to recheck what I'm doing, as I'm doing it.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor O:
This happened to me once. What I did was put catalyst in a mist spray bottle and carefully misted the piece. I shut the shop up tight and left for the day (to pout). When I came back the next day everything was great - nice and dry. I re-sprayed with another coat and the customer is still happy years later.
