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Hi Heads, I've got a slight dilema! 2 days ago I coated a billboard with "Danacolor" bulletin white. Today I did pounce patterns and began to paint. The paint wouldn't stick, What's up? I've painted a lot of bulletins and this is the first time that has happened. Could it be the cold weather (25 degrees at night and about 35 during the day)? Anyone know the cause and a remedy (besides sanding, 12' x 48' is a lot of sanding)? Any help will be greatly appreciated! Thanks, Glen
-------------------- Glen Lemmon Visucom Art & Signs Pocatello, ID visucom@hotmail.com www.visucomsigns.com Posts: 35 | From: Pocatello, ID | Registered: Mar 2002
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Glen, most paint cans specify 50 degrees or warmer.
Years ago I painted all the blanks for an entire subdivision in our unheated garage. It's pretty mild out here in the winter so it seemed safe. The weather forecast was low thirtys overnight. Well, the paint skinned over so it looked dry, but it was spongy underneath and still spongy two days later. I wound up scraping them all off with a putty knife and wiping down with paint remover.
Based on that, it sounds like maybe you let them get too cold while drying.
By the way, sanding doesn't work because the paper gets all gooey almost instantly.
-------------------- Victor Georgiou Danville, CA , USA Posts: 1746 | From: Danville, CA , USA | Registered: Dec 1998
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You might try a little hotter thinner. When paint dries the thinners evaporate yet as the temperature drops this evaporation process slows making paint thicker and gummier on cold days. the only way to combat this is to use a thinner that has a lower flash point, thus it evaporates faster.I have experienced the problem you mention and sometimes a small amount of lacquer thinner will solve the "greasy" reaction you are fighting. The normal thinners(petroleum distilate) are for normal weather. As the temperature drops these normal thinners make the piant react almost like an oily film that floats on the top when it should have a bit more bite and drag.I can remember trying to spread paint on billboards back before I knew about this and often dreaded cooler temps due to the way the paint reacted and my lack of control over that. As you try the hotter thinners like xylene and toulol remember they don't need near as much in volume to do the same job as normal thinners on a 70 degree day would take.
Here is my list for thinners in the order that I have used them to combat temperature changes in the past.
petroleum distilates (normal temps) naptha xylene toulene (coldest temps) Many times I will experiment with mixes of one or 2 of these thinners to make the lettering flow and stick like it was 70 degrees when actually it is much colder.I may have the last two mixed up in order of flash points so if anyone knows for sure please correct me.
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You could try wiping the painted areas with a clean damp rag, and that sometimes removes a film that causes that fisheyeing. If that doesn't do it, I'd add a few drops of fish-eye eliminator to the paint, just enough to get the crawling to stop, then it should be alright. Any brushes you use in that mixture should be cleaned thoroughly several times with silicon remover, like Ditzler Wax and Grease Remover, before putting them away.
That's what I'd do, PROVIDING the paint is dry and not soft from that nasty old cold weather y'all got up there.
-------------------- Jeff Ogden 8727 NE 68 Terr. Gainesville FL, 32609 Posts: 2138 | From: 8827 NE 68 Terr Gainesville Fl 32609 | Registered: Aug 2002
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the reaction probably is not from contamination on a billboard. I've had this problem before and it appeared to be from the surface of the original paint being almost covered with an oily film, yet it only occured in the temperature range Glen describes.There was no oily film the dry paint layer just seemed like it had a film. The reaction I get that is similar to Glen's is that the lettering or next coats goes on like it has a layer of grease between the paint and doesn't want to cover or flow. It is due to temperature reactions between coats of bulletin enamels. As it gets cooler normal thinners act almost oily as they thicken. Any attempts to prevent it with fish eye eliminator only created more fish eyes. It is common in the winter here outside on billboards as they are usually a bit above the tree lines and somewhat cooler than ground level.
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Thanks guys, Now that you mention it Tim, I used to always use naphtha and just recently switched to mineral spirits because it's cheaper. So that's probably what happened. Since the damage was already done, I figured some heat might help so I used a small propane torch and carefully heated the areas, (moving the torch constantly) I needed to paint and It worked like a charm. I wouldn't want to do it again though. I'm switching back to naphtha! Thanks again, I appreciate your input. Glen.
-------------------- Glen Lemmon Visucom Art & Signs Pocatello, ID visucom@hotmail.com www.visucomsigns.com Posts: 35 | From: Pocatello, ID | Registered: Mar 2002
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As a point of reference, enamels are manufactured for use at 70 degrees and 50% humidity. One has to adjust for other temps and humidity. Not only hotter solvent but a small hit of dryer will help it to kick in lower temps. We have used a torch or heat gun to get the dryer to kick before too. You may find that it will kick in the mid-day sun even on a cold day too. Even at that, the paint is never as durable when cold cured below 40 degrees.
-------------------- Kent Smith Smith Sign Studio P.O.Box 2385, Estes Park, CO 80517-2385 kent@smithsignstudio.com Posts: 1025 | From: Estes Park, CO | Registered: Nov 1998
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