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A while back I had a post asking if anyone had ever cleared laytex paint. Well now I have my answer. I cleared some water based porter paint (laytex) with PPG DAU 75 clear and wet look hradner. It turned out very nice. The reason for doing this was that the customer wanted it to be more resistant to water since it will be near a lake. But the problem was we had already painted the sign. The clear is Urathane and after some really thick coats (with no runs) it seals the wood pretty well.
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Thanks, Scot !! There are a LOT of us out here that use latex 90% of the time. If you can, please post more info on the PPG. Their website and the particular products you used for the clearcoat. Thanks again !!
-------------------- John Smith Kings Bay Signs (Retired) Kissimmee, Florida Posts: 817 | From: Central Florida - The Sunshine State | Registered: Jan 2000
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the only problem i have seen with urethane clear is that it tends to yellow with age. in my humble opinion, clear coating latex is not necessary.
I used it the way the directions perscribe and I shoot it thru an HVLP gravity fed paint gun.
The full cost for a quart is around $35.00-$40.00 and we just add that into the price of the sign.
Mark, I would have to agree that when we used Thompsons or Winwax etc. that the urathane would yellow. But for some reason the Automotive clears do not seem to yellow or if they do it must be very slight. Maybe Mike Lavallee could fill us in on why the automotive clears dont seem to yellow. I believe he also does alot of automotive work
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you can buy a can of clear tinting base, were you buy latex house paint ect. it is white or cream when wet and dies clear. I have not used it on a latex sign. but have used it to coat over glitter on props and parade wagons. Also for mixing semi transperant colors for effects. If you have a small paint maker in your area. they will sell you the pure uncut cut acrylic latex which is clear. it is thicker than the paint. I have used that for make up effects and water proof glue/sealer. Only problem with the pure latex acrylic that it is corrosive to paint cans after year or so. the tinting bases come in clear, deep, medium and light. the colors of the others vary slightly from brand to brand. but each type is used for a range of colors. deep base for darker colors, ect for the rest. A side bar is when you leave latex paint dry in a plastic container you can tell how good the paint is buy the size of the piece of dryed paint you can pull up after a couple of days. the bigger the section that comes up the more acrylic base used to make the paint. the more the paint costs and the longer it will last. The local paint plant Kush paint. makes stains and boat paints. the local boats love them. the stains last and last to. extenders on a paint label can be translated to H2O for waterbase and some form of thinner for oil base.
-------------------- PTSideshow, been there, probally done that. Wizard Works Show Supply Magic Props FX Signage Banners Ect. Posts: 120 | From: Mount Clemens,MI,USA | Registered: Nov 1998
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Ok....this is going in a reaaaaallly dangerous direction. Scott,you did the right thing by doing a test piece but this is a no-no,despite what others here may tell you and here's why : Any automotive grade urethane clear is designed to work primarily thru chemical adhesion,which means it needs to cross link into the basecoat and become one integral unit,with latex paint thats not gonna happen. You can get it to sit on top of the latex all day long,but you're cheating time and chance. One chip,ding etc or anything that breaks thru the surface of the clearcoat and once air and moisture get underneath,add in a little time and it's going to come off in big pieces.It may look fine when it sits there,but with latex you also run the risk of having additives or sometimes of emulsions percolating up to the surface as it drys and you can have a contamination problem no amount of cleaning is going to get rid of. Latex or other waterbase paints also aren't gonna be as solvent resistant and tuff as automotive grade stuff and theres more than 1 chance that when you hit em with the clear its gonna eat into the base and either wrinkle it or give it a grainy,rough appearance underneath the clear,or the solvent from the clear is gonna go straight down thru the latex,into the wood and come out in the form of pinholes somewhere else,prob the first good day in the sun the thing has. You got it to work mostly because you shot the DAU 75,thats a relatively user friendly,thin,low solid product.....with one of the newer tech higher solid clears esp using a HVLP,& more than likely the whole thing will take on a haze once its finished compared to the original color,and some of them dry pretty violently in comparison to how latex sets up,so if you try to 'cheat the envelope' and push the time on the sign you could wind up with a grand crapping mess thats dry and hard as concrete b4 you can do anything about it. There's plenty people here that use Pelucid as a topcoat and while it's a similar product to automotive clear,its not the same thing and its designed to work a little differently and actually a better choice. It's not foolproof either when putting it over waterbase products but it does work better for those kind of applications. You asked why automotive grade urethanes dont yellow...to a degree it still may over a long time period,but about 98% of them now contain UV filtering agents and are just flat out a much tuffer,superior product to other urethanes. There is no waterbase system of any type out there right now thats as strong as they are,they're designed to be part of the final product not a stand alone topcoat or a sacrifial coat and thats what makes the diff. Just my .02,hope it helps.
-------------------- Gavin Chachere Plotter in the garage,New Orleans La.
"Sgts Shugart and Gordon again request permission to rope down to crash site two" Posts: 1223 | From: new orleans.la. | Registered: Mar 2000
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