Paint Compatability: What Clear Over Acrylic Lacquer?

[stratoskier]

Hi,

Over the past few weeks, I've read over a lot of old posts, but I'm still a little confused about this ---

I used Dupli-Color acrylic lacquer spray cans for the color coat on my project. It's been drying for a couple of days and I think I'm about ready to start the clear coats (to be sure, how long SHOULD I wait before clearing?).

I read a few posts here or maybe at ReRanch that said the Dupli-Color clear took forever to cure so I might want to avoid that product. I also read Jeremy's tutorial in which he spoke very highly of polyurethane. Can poly be used over acrylic lacquer with no compatibility issues? If so, what brands would you recommend -- Deft? Minwax? Other? I'm mostly concerned about combining products that might react together in some undesirable way.

Thanks much,

Bert

[syxxstring]

Stick with in a system and read the directions and follow them.

Anything else is just a guess that something may not work out for more than a week, a month, or a year.

Jeremy was refering to Automotive Urethanes, uro's are a very different animal than the wood working products.

[CrazyManAndy]

I know many ReRanch members have used nitro clear over acrylic colors without issue. I don't know if it's guaranteed to work, but I would certainly test it on scrap before trying. But as syxxstring said, it is best to stick to a system (though, I to have heard many bad things about dupli-color clear). You might ask the folks on the ReRanch forum about their experience with nitro over acrylic, as well.

CMA

Edited June 3, 2008 by CrazyManAndy

[syxxstring]

My point is that spraying a scrap just lets you know that the immediate result is not bad. Doesn't tell you what it will do in a year.

Talking to HOK's testing and tech guy he will not call that even a test. They bathe things in uv, solvents, etc... then examine everything under an electron microscope and other lab equipment. That is a test, that will let you know that a product will work or fail.

It's not uncommon to see people that mix paint systems have delamination, bubbles, cracks, or other problems a 6 months to a year down the line. While an acrylic lacquer may be an acrylic lacquer the solvents, strengths and formulas may vary. With in the automotive paints many people have said a uro's a uro, while thats true systems have different purposes and mixtures. With in Valspar you have several brands from a refinish clear and House of Kolors UC35, they are not compatible even from the same parent company. The UC35 is designed for custom work where finish thickness can be 4 or more times the thickness of factory paint, so it over refinish products the solvents are too strong and will cause issues. Refinish clear over a full custom paint job and the solvents aren't strong enough to bite all the way down and form one solid film, you saved a few bucks but have a paint job that will fail much sooner than it should have.

The only reason to leave a paint system is if you think your smarter than the chemists who designed it or to save a few bucks and risk your whole project blowing up eventually. Neither one works for me.

In the days before I had an HVLP gun collection I used some of Duplicolor's clears with no issue. Read the directions and follow them as far as finish thickness, time windows, and application technique. If its put on too thick or in too thick of coats it will take longer to cure if it ever does. Funny Reranch guys saying duplicolor will take for ever to dry when they are spraying Nitro with much longer curing windows, use Nitro and wait a month no thanks.

Edited June 3, 2008 by syxxstring

[CrazyManAndy]

Just to clarify, I know a scrap test doesn't tell you what will happen down the road, which is why I added that it has been done, without issue, by others. Finishes that are well over a year old, and no trouble as yet. I'm not saying it is a good idea (at least, as a general practice), but he can make up his own mind.

CMA

(Edit: You are right in that all acrylics are not equal in formula, even if they are in name. It would perhaps be better to specify the ones used by the folks I mentioned. Most, if not all, of them used either Dupli-color or Rustoleum colors.)

Edited June 3, 2008 by CrazyManAndy

[stratoskier]

Thanks for the info, guys! It's very informative listening to you folks discuss the potential issues.

I think I'll play it safe and go with the DupliColor clear. I'm really in no rush to get this project done, so it's not a problem if it takes some time to cure. I'll try to keep the coats reasonably thin so drying time is within reason. I was also considering taking the body to a woodworking place to have the pros spray the clear, but based on your input, that's probably not a good idea since I have no clue what they'd use.

I love this site!

Bert