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Bonehead conversion varnish mistake7/26/15
I got ready to topcoat a 3d cnc cutout that took 20 hours to cut out, and like an idiot, I used lacquer thinner to thin water white conversion varnish instead of xylene. After half a day of drying, the finish was still very tacky. I added another coat of heavily thinned varnish (this time with xylene) to try to reduce the tackiness.
After two days, the piece is still tacky, though to a lesser degree. Is there anything simple I can do to make the finish cure?
Call the techs for the manufacturer of that finish product. If you have to strip it there professional stripping products that you can't buy in a big box store.
Companies like Benco sales and other specialist that focus on really powerful strippers. Always follow all safety precautions!
hmm... i use lacquer thinner all the time in my sherwin williams conversion varnish. Never had a problem. Sounds like you didnt add proper amount of catalyst
I have to agree with Kevin
The quick fix — doesn't always work, but it did for me on a rack of doors — if you didn't mix enough catalyst is to mix up another batch of topcoat and put in more than the recommended amount if catalyst.
The idea is that this new "hot" topcoat will kick your under catalyzed coating. That's the idea. You'll know if it works, everything will feel cured.
And if it doesn't work, strip or wash everything off and begin anew.
if you try to kick the under catalyzed coating in with over catalyzed product your customer will be calling you soon after delivery when it starts curing out. Shrinking, cracking, peeling and full of "Acid Bloom"... tuck your tail and chemically strip the piece and start over... we have all done it...
@andy - so what route did you take?
Wow. I just finished posting a new query about CV cure. (I feel like a bonehead for not searching for this thread before posting) Thanks, all sounds good. Wish me luck, going downstairs now to apply the hot coat. Just have to worry about thickness!!!
Well, last week I did the "hot coat" with almost double the catalyst (5.5%) and it did the trick. Cured enough to thoroughly sand the table top (had bugs in it anyway) then apply a proper final coat. Daniel's advice was right on! Thanks for that boost of confidence you gave me before re-coating!
Ken, I'm glad this worked for you. It did work for me. It's a maverick approach that will never find any official sanction, but it's a workaround that is at least possible. It has a better track fecord than, let's say, leatril has or tarot cards, lol.
In retrospect I would also add to my suggestion to mix in some "hot solvent" (something to vive your fresh over-catalyzed application some extra solvency, also). My tbinking is that you want to increase or insure a good melt-in of the application so that everything vets catalyzed.
Who doesn't like a good crosslink, said no undercatalyzed coating ever.
Thanks everyone for the suggestions.
I ended up coming to the conclusion that my catalyst was too old. I let the cutout sit and cure in my shop for about 5 days to see what would happen. It eventually got dry enough to sand. It was still somewhat tacky, but hard. I got some fresh catalyst and sprayed a light coat on. That did the trick.