TransAmMike Posted October 15, 2020 Share Posted October 15, 2020 So yesterday with temp around 75-78 degrees and mid 30 humidity I sprayed '57 Chevy Duplicolor Mica and got a beautiful smooth shiny finish but I forgot to spray the trunk lid. So today, temp about 80 and humidity around 55 , I sprayed the trunk lid and it dries out flat. I can only assume its the slightly higher temp and humidity but good lord I can't believe that slight deviation can make that much of a difference. Anyone else experience this?? Quote Link to comment Share on other sites More sharing options...
Jack L Posted October 15, 2020 Share Posted October 15, 2020 Humidity plays a big part with Dupli-color paint in my part of the world , Manvel Tx gulf area Quote Link to comment Share on other sites More sharing options...
TransAmMike Posted October 15, 2020 Author Share Posted October 15, 2020 This was my first time using Duplicolor so I have no experience factor. The first can I got I returned because it was sputtering and squirting out the paint and dripping every where. Quote Link to comment Share on other sites More sharing options...
SCRWDRVR Posted October 16, 2020 Share Posted October 16, 2020 (edited) Dupli-color is very humidity sensitive, I keep a small heater close by when spraying it. the hot air from the heater is dried out and will take the blushing out of the paint when still fresh. Just be careful not to have the heater to close... When I worked in the body shops we did our spot painting in an air conditioned area to help combat it Edited October 16, 2020 by SCRWDRVR Quote Link to comment Share on other sites More sharing options...
TransAmMike Posted October 16, 2020 Author Share Posted October 16, 2020 Well it definately sprayed and looked better in the cooler low humidity. Will be more favorable conditions tomorrow. Quote Link to comment Share on other sites More sharing options...
TransAmMike Posted October 16, 2020 Author Share Posted October 16, 2020 Yay!!! Reprayed the trunk lid that was dulling out. At first sprayed with temp in the garage in low 70's but humidity was showing 55. Still was dulling out but with some shine in spots. Than I opened the garage door and got the temp slightly lower but the humidity at 45 percent. I put the can in hot water for about 5 minutes and sprayed again after previous coat drying about 30 minutes. Got perfect shine. So i'm guessing 45% humidity with warming the paint a bit is the answer. But who REALLY knows. Quote Link to comment Share on other sites More sharing options...
Tom Geiger Posted October 17, 2020 Share Posted October 17, 2020 Look at your Duplicolor can to see if it’s a color that requires a clear coat. That would spray dull but will come to life once sprayed with clear Quote Link to comment Share on other sites More sharing options...
TransAmMike Posted October 17, 2020 Author Share Posted October 17, 2020 The can doesnt't say anything about having to clear coat but your're right, clearing would have solved the issue. When I had the first can I bought that was messed up I tested a panel that I sprayed that had dulled out. I just brushed on some old Future and wow, it definately had a deep shine. It just so happens I sprayed a custom VW I'm building and forgot to paint the front and rear bonnets (I guess that how ya spell it) so have to buy another can so I'll see how that comes out. i Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted October 17, 2020 Share Posted October 17, 2020 Duplicolor colors, particularly metallics, being lacquer, are prone to "blushing" in high humidity. This can range from an entire panel or body appearing "flat", to just a little milkiness on edges. USUALLY, the blushing will polish off solid colors, and some metallics. BUT...some metallics don't like being polished, and will become blotchy if you try. In that case, the blushing will disappear with a clearcoat...and if the clear blushes, it will polish right off. This hood is Duplicolor, as-shot, with no polishing. Moderate temp, low humidity day. Quote Link to comment Share on other sites More sharing options...
Painted Black Posted October 17, 2020 Share Posted October 17, 2020 So why can't they make the color paint dry glossy like the clear does? Quote Link to comment Share on other sites More sharing options...
Bills72sj Posted October 17, 2020 Share Posted October 17, 2020 Humidity is the biggest factor. I bought a humidity gauge and paint when it is less than 40%. Raising the temp of the air and the paint can can help crutch days that are borderline. Quote Link to comment Share on other sites More sharing options...
TransAmMike Posted October 17, 2020 Author Share Posted October 17, 2020 Waiting for a less than 40% day in below the mason dixon line is a rarity. I'm just south of Nashville and seldom is there what you could consider an ideal day. It just so happens today is perfect and I'm out of paint and can't get more until Monday. Oh well. That hood is perfect and a beautiful green. Cool looking Olds too. Quote Link to comment Share on other sites More sharing options...
Chariots of Fire Posted October 17, 2020 Share Posted October 17, 2020 I've had the same issue but have found that some polishing after the paint is really dry will take care of the problem. The main reason I like Duplicolor so much is that is a fine pigmented paint and does allow for polishing and some sanding between coats without getting soft in the process. Found a can of Duplicolor acrylic red the other day at Ollie's. Haven't tried it yet but will only do so an a sample piece of plastic after priming just to see what happens. Quote Link to comment Share on other sites More sharing options...
peteski Posted October 19, 2020 Share Posted October 19, 2020 On 10/17/2020 at 1:19 PM, Painted Black said: So why can't they make the color paint dry glossy like the clear does? Gloss can also blush in high-humidity conditions. The paint is not the problem. The problem is due to combination of the solvent evaporation rate and the dew point of the ambient air. Evaporation of the volatile solvents from the freshly applied paint (as it dries) cause the model's surface (and the paint layer) to cool. If it cools below the dew point of the ambient air, the moisture in the air starts condensing on the paint's surface. That affects the further solvent evaporation, and the glossiness of the paints surface. The condensed moisture causes microscopically rough surface which is no longer glossy smooth. That is how blushing happens. Different paints use different solvents. Solvents which have the fastest evaporation rates will cause a stronger cooling effect than slower evaporating solvents. So some paints are less susceptible to blushing (again depending how high the dew point of the ambient air is). Quote Link to comment Share on other sites More sharing options...
TransAmMike Posted October 19, 2020 Author Share Posted October 19, 2020 And without stating the obvious (LOL), what is the best solution to the dulling problem. Or is there really any solution other that just paint and deal with. Quote Link to comment Share on other sites More sharing options...
Painted Black Posted October 19, 2020 Share Posted October 19, 2020 Thanks Peter, very helpful. Quote Link to comment Share on other sites More sharing options...
Ironman63 Posted October 19, 2020 Share Posted October 19, 2020 13 hours ago, peteski said: Gloss can also blush in high-humidity conditions. The paint is not the problem. The problem is due to combination of the solvent evaporation rate and the dew point of the ambient air. Evaporation of the volatile solvents from the freshly applied paint (as it dries) cause the model's surface (and the paint layer) to cool. If it cools below the dew point of the ambient air, the moisture in the air starts condensing on the paint's surface. That affects the further solvent evaporation, and the glossiness of the paints surface. The condensed moisture causes microscopically rough surface which is no longer glossy smooth. That is how blushing happens. Different paints use different solvents. Solvents which have the fastest evaporation rates will cause a stronger cooling effect than slower evaporating solvents. So some paints are less susceptible to blushing (again depending how high the dew point of the ambient air is). Very helpful info to understand why it happens. Thanks Pete! Quote Link to comment Share on other sites More sharing options...
peteski Posted October 19, 2020 Share Posted October 19, 2020 3 hours ago, Ironman63 said: Very helpful info to understand why it happens. Thanks Pete! You're welcome. IMO, knowing about the chemicals and understanding the processes I use in my hobbies makes me a better modeler. I'm not an expert, but I try to educate myself as much as I can. Quote Link to comment Share on other sites More sharing options...
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