# foggy clear coat breakdown



## bmwr71 (Jan 30, 2010)

Fellers, taking a quick break from drowning in railroad pictures from Pintrest to ask around. 

Over the years, I have had a problem that I never could figure the solution to but recently had one proposed and also watched a U Tube with a similar idea. I always matte finish my weathering jobs with Rustoleum or Krylon to protect the work. And if you guys are into it and live in the humid world, spect you have had your lovely weathering jobs ruined by foggy clear finish. Have read that the water from the humidity gets mixed into the spray and is trapped making the fog. Sometimes just waiting till the humidity drops and coating again saves the day, but many times it is no help. Have had some so bad that it looks like sugar coating.

So some guy from the Ford Ranger yahoo group started emailing me privately and we kicked around different subjects and found out he does military models and some ON30. He told me to try a hair dryer and said later, a heat gun, to make the fog go away. I also found a U Tube where some guy was doing a satin finish on wood that fogged and he used a heat gun to make it go clear. I tried the hair dryer and maybe some got better. For sure that sugar coated looking stuff didn't go clear.

Wondered if anyone had experience with this? And wonder what humidity level makes it go from clear to fogged? And is it relative humidity or just the quantity of moisture in the air as a smaller amount of moisture in the air will make for a higher relative humidity at lower temperatures?

Over the years of doing weathering jobs on cars, I have an inventory of cars with fogged finished. I also wonder if the age of the fogged finish would determine if the heat trick would work?

Doug


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## choochoowilly (Oct 31, 2016)

I have never used the heat trick but have sprayed fogged ones with acetone sprayed with a air brush


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## armorsmith (Jun 1, 2008)

High humidity is the bane of any painter. Dependent on where you are painting .... indoors, outdoors, etc. Small scalers have it much easier in that a simple solution for them is adding a de-humidifier to the basement (assuming you have one). I live in Florida so humidity is always an issue. My best time is to wait for lower humidity - in the less than 70% range. If I had the ability I would room off a section of the garage and add a de-humidifier. 

As for solutions to existing 'blushing', I have never heard of a successful solution.


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## Nick Jr (Jan 2, 2008)

Doug, I agree with your assessment of humidity in the air. The spray fronm the can is cool, acts just like your AC unit relieving pressure the propellent absorbs heat. The moisture in the air condenses and mixes with the paint causing the cloudy appearance. I don't know if applying heat will make a difference, but I think you would have to do that while the paint is still wet. Just like armorsmith I have a room in the house that is atmospherically controlled so I don't have that problem. LiG


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## bmwr71 (Jan 30, 2010)

I used to do all my fine scale modeling in my backyard. Now I have refined the experience by doing it in my friend's barn. Allows for authentic dust in the paint. No way to dehumidify either and it gets darn humid around these parts. I have several cars that have the fogged fever. I know that I should wait until some drier times, but hard to wait to see a finish product. Seems cool weather works best so I assume perhaps it isn't relative humidity but just the quantity of water in the air, like grams per cubic foot, but have no idea how one would measure that.

I guess I need to remember to dig out the heat gun and give it a try. It worked for the guy in the video. Maybe a slightly melted tipper car hopper might have an all new abused look to it. 

Might also see where I left my air brush and try acetone. I always hate using an air brush because of cleanup, but no cleanup after acetone, might help clean the brush. Perhaps could add a bit of dark ink and see what I get. Being somewhat lazy, no, busy, I just use spray cans and ink washes and cinnamon and chalk dust and tempera powder, etc for weathering. It is all in fun.

Wish somebody sold acetone in a spray can

Doug


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## jimtyp (Jan 2, 2008)

Doug, I use a fair amount of Krylon UV Matte. With this particular paint my experience is anything above 40% is risky. I live in Colorado, mostly low humidity, but one day I got the "fog". I called Krylon and 40% or less humidity was there recommendation. If you do get the fog, I've read that spraying "gloss" over it can clear it up a bit, but I haven't tried it myself.

-Jim


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## bmwr71 (Jan 30, 2010)

So been looking for my heat guns and as they put in a Harbor Freight around the corner, bought another one to lose. I tried the heat and it did no good. I tried putting a coat of matte clear and then heat it and also no good. I soaked a paper towel in acetone and I wiped a wood clock face I had done a few months ago in satin clear that fogged and everywhere the towel could reach, fog went away and made the clear coat tacky. I tried the acetone wet towel on a fogged car and part of the fog seemed to go away. Now I want to find where the heck I left my air brush stuff. Perhaps how wet one gets a piece with acetone will determine the results.

Regarding the video where the guy used a heat gun to make the fog go away, he said he had shot the coat a day before and I wonder if how much a paint job has cured makes a difference? I wish I knew what really goes on with the moisture in the coat, what causes the fog to be there, the chemistry or the mechanics of it? It does seem that I never have it happen with gloss clear. I have been painting some Christmas cars in a Krylon high gloss glaze and no fog at all, even on the very high RH days.

I will give a shot with the gloss over the fog and see what that does. Do wonder if I matte back over the clear if I will get matte or not? Sometimes it seems like if I do several coats of matte, I get more like semi-gloss. One matte finish I use for some other hobby metal objects turns glossy with three or more matte coats. And then wonder what the difference is between matte clear finish and flat clear finish? Wonder if say matte finish forms some surface that is say not smooth on a micro level making it diffuse the reflected light?

Gotta get back to today's thousands of railroad pictures from Pintrest, Doug


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## bmwr71 (Jan 30, 2010)

Tonight I tried the gloss clear coat and much, but not all of the fog, went away. The really bad stuff that looked almost sugar coated changed somewhat but is still a problem. Might be different when the clear fully dries, will see. And will try to be patient in trying to coat over the gloss clear with matte and wait until less humid days come in the fall.

Being too lazy, I mean busy, to find my air brush stuff, stopped at the brand new Harbor Freight around the corner and bought a touch up gun. *It cost like $13 and I had a coupon for 20% off and a free flashlight coupon, so no big financial loss there. Will use it to spray acetone and see the results on the fog.

And being a very experienced kid, I thought about holding a lit grill lighter in front of the acetone spray and see if makes a fun flame thrower. Might also make for a hot time with roasted skin.

Doug


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## bmwr71 (Jan 30, 2010)

If any of you kids are stilled interested, here is a report on tonight's experimentation.

Filled my new cheap touch up gun with acetone and sprayed a couple of fogged cars. Not sure if any parts got better, some got worse. The cars were wet with acetone, but the finishes never got tacky. So many variables here like might have to do with tonight's humidity level, amount of trapped moisture, coating thickness, etc???? I have no idea. Might try toluene or MEK. Flammable fun.

I checked and the cars I sprayed with gloss last night and the fog had gone away in much of the areas, but of course, the finishes were gloss and not the desired matte. I tried spraying more gloss on the cars and more areas lost the fog, but not all. I lied to myself when I told myself I would wait to try the matte over the gloss until the humidity was down and i couldn't wait to try and see what a matte coat would do. I did some quick passes with Krylon matte and it did seem to tone the gloss down a bit. Steel wool might also be an option, just difficult to get in some areas.

Doug


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## bmwr71 (Jan 30, 2010)

Have still been researching and experimenting on the problem. Tonight I tried the heat gun on a wood water tower. The fogging actually seemed worse when hot but, went back to the original fogged look when cooler. I tried rubbing it with MEK and that did nothing. I sprayed it with gloss clear and most of the fog disappeared. For some reason, the fogging on edges is worse on items and won't go away. I sprayed gloss clear on some other resin cast items and the fog disappeared.

I emailed a friend that is an ink printing expert as ink is similar to paint. The only thing he suggested was to use a less hygroscopic solvent, but admitted that is not possible with a spray can. He said materials like clay are added to gloss to make matte clear. And maybe the solvent used in matte clear spray is different than that used in gloss. Does seem to smell differently.

I emailed with a long time auto painter friend asking about what to do. He had noting on what to do for a finished fogged job. He did suggest when spraying to prevent fog, spray light coats and wait a good while between coats and maybe use a heat lamp on the item being coated.

Doug


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## Railroadcollectors (Jun 20, 2021)

bmwr71 said:


> Fellers, taking a quick break from drowning in railroad pictures from Pintrest to ask around.
> 
> Over the years, I have had a problem that I never could figure the solution to but recently had one proposed and also watched a U Tube with a similar idea. I always matte finish my weathering jobs with Rustoleum or Krylon to protect the work. And if you guys are into it and live in the humid world, spect you have had your lovely weathering jobs ruined by foggy clear finish. Have read that the water from the humidity gets mixed into the spray and is trapped making the fog. Sometimes just waiting till the humidity drops and coating again saves the day, but many times it is no help. Have had some so bad that it looks like sugar coating.
> 
> ...


Be careful using heat on plastics. It will warp. I found gently using Deluxe Materials “Strip Magic” works great. It’s a paint stripper for plastic hobbies. Just be careful and wet the top of a Q-Tip and dab off excess. Keep the Q Tip as dry as you can. Gently rub only the area with the problem. I put flat sealer on water slide decals on a plastic model in high humidity conditions. It left me with a milky white cloud. The Strip Magic cleared it right up. Think of it as taking the mistake off a layer at a time. Don’t hurry. Only apply a small thin layer on then gently wipe with a clean dry Q Tip. It should do the trick


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## Railroadcollectors (Jun 20, 2021)

Railroadcollectors said:


> Be careful using heat on plastics. It will warp. I found gently using Deluxe Materials “Strip Magic” works great. It’s a paint stripper for plastic hobbies. Just be careful and wet the top of a Q-Tip and dab off excess. Keep the Q Tip as dry as you can. Gently rub only the area with the problem. I put flat sealer on water slide decals on a plastic model in high humidity conditions. It left me with a milky white cloud. The Strip Magic cleared it right up. Think of it as taking the mistake off a layer at a time. Don’t hurry. Only apply a small thin layer on then gently wipe with a clean dry Q Tip. It should do the trick


. In the future, only spray clear on low humidity days and spray in thin coats. Let first coat dry for at least ten minutes then apply second coat. Heat shouldn’t b used to dry the clear. Just let it dry naturally.


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