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Anyone using CV over todays all to common finger jointed primed moldings. We have a new finisher who is reluctant to use our usual Sherwin Williams surfacer and CV over the factory primed millwork. We do work with a company who will run clear hardwood moldings for us but small runs are not a lucrative option for either of us.
Sounds like he takes heed and pride in his work. He's obviously been burned before and has had a paint failure and someone pointed the finger at him. He has good reason to be cautious. Without knowing the previous coatings exact specifics its a crap shoot putting your coating over the top. I have done it with great results as well as I've had finish failure and the previous coats wrinkle or no adhesion. If prepped very well and the Sherwin coating doesn't wrinkle the primer or cause any lifting around edges his finish schedule should be fine. Let him do some test trim with a full test schedule and cure time..... If you have a defelsko adhesion tester for a crosshatch test would ease his mind to know the coatings are playing nice together.... when it all works as needed run with it..
We use CV from ML, We sprayed vinyl sealer over a pre primed solid Poplar crown couple months ago, just got a call from the GC last week that our crown starts to flake/pell off. The money we tried to save by buying the crown and a little more, will be spend to run the crown ourselves, finish and install again, not worth, don' do it.
I to have done this with several failures usually peeling down the road. The beauty now sw makes a waterbased primer called gen 2 that can be used under all there lacquers and conversion varnish. I shoot a coat of this over the preprimed and so far no issues. Good luck.
I'm not sure what they use as primer but I just had a project recently using primed shiplap board that needed to be painted the same color as the cabinets
Listen to your finisher.
The pre primed crap doesn't work with any CV I have shot over top of it.
I tried it, like I'm sure most guys have at some point. My thought process was... surely whoever is making this pre primed moulding is using a primer formulated for solvent based finishes... NO.
single base color coat... looked okay.
final top coat (2nd color coat)- peeled/ wrinkled. But not immediately so of course I left the shop thinking, job well done. Next morning filled with expletives.
Ended up stripping/ sanding down to bare wood, spraying primer, and taking it back to final coat.
Any little bit of primer that I didn't get out of the tiny detail areas like the crease in a 1/16 step, I ended up getting small wrinkles. I was luckily able to JUST cut around those areas and put up the crown pieces needed.
I run most of my own stuff now in soft maple or have it run for me.
I also noticed the finger joints telegraphed through the finish. That's when I was shooting a single coat of clawlock II, and 2 color coats. Might not do it with 2 coats of primer, but of course... added time/material/money for that extra step.
We can usually get our primary builder to order a few lengths of the custom crown for our use around the cabinetry that is not preprimed. You just have to ask.
Some times it doesn't happen. They provide us with a preprimed piece of solid poplar molding.
We have always sanded off all of the primary. Then painted it with our primer & cv or whatever else we use.
Sanding it off is included in the price. Just for the piece of mind, I would sand it off.
cv is a hard brittle plastic. They are prepriming with a soft flexible paint. The two are not compatible. You can usually go soft over hard. Hard over soft will fail.
My simple solution is that I keep Aquaprime in my shop at all times. It's a WB primer from Chemcraft that is formulated to go over anything, but also go under any CV, PU, precat, or WB. I basically just do a barrier coat of Aquaprime on anything that comes into my shop where I'm not 100% sure what the finish underneath is. Been doing that for 4 years and I've yet to have a problem.
Tyler, do you know if Aquaprime can be used on exterior projects?
I asked my finishbrepnthat not too long ago. This product was initially developed for window manufacturers.
It does not get an exterior "rating" but he says people use it all the time for that and he's never had it fail for anyone
Thanks Tyler.. I looked at the PDS and they make no mention of it, but then say it can be used with any Chemcraft product.... so I guess that includes exterior stuff... but they never specifically say that. Probably covering their a$$