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Gloss Paint Going Flat On Me...

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rosko_racer

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What does make gloss paint go flat when it is drying?

I have seldom have great looking red or white gloss paint jobs direct from the can. I do the primer prep, let it dry, then apply 2-3 coats. When I check 20-30 minutes later the paint is barely gloss or totally flat. I get this from the Krylon old formulas. I have painted during the dry season, low or high humidity, cold weather... you name it, and get the same results. The only one that I have had great painting out of a can is with black. To "recover" I use Future which never fails me...
 

luke strawwalker

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Hmmm... there can be several reasons for this...

Old Krylon is a lacquer, and lacquer usually dries faster because the solvent is 'hotter' (evaporates more easily). Are you sure you're not getting 'dry spray' where the paint is actually hitting the surface with some of the droplets already 'dry' (solvent has evaporated) which then don't flow out properly on the surface. If this is the case, try spraying closer to the rocket and moving the can a bit faster to prevent runs/drips. This shortens the distance the paint droplets travel through the air and reduces the solvent evaporation before the paint hits the surface and flows out.

The other thing may be heat and humidity related. Hot air evaporates the solvents faster, as does lower humidity. High humidity can cause 'blushing' and other nasty effects that can mess up a good paint job. If you're having this problem across many different environmental conditions when spraying and with different batches of paint (sure it's not old paint or something causing the problem) then you might need to experiment with your technique, maybe get closer to the rocket but move the can a bit faster or something like that.

Another possibility-- are you using a good compatible primer?? If the primer isn't fully compatible, it can 'suck' the solvent out of the paint and cause it to appear chalky. Also make sure you use a tack rag to take all the sanding dust off the model before painting, as the dust can do much the same thing.

You might also try putting down a 'sealer coat' of white over the primer before you spray the red... that should help the red by sealing off the primer before the red goes on.

Hope this helps! OL JR :)
 

rosko_racer

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Thanks Luke:

I am using old formula Krylon primer and overcoats. I usually paint 7-10 inches from the rocket and the last coat is usually a "wet coat" of paint. I just tried your method of painting closer and moving the can faster. Gave the rocket one coat of old Krylon gloss white and it is drying now... will post the results in about an hour... I painted in the garage but moved the rocket inside the house to dry... it stinks to high heavens!!!
 

luke strawwalker

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Thanks... hope that works for you Rosco...

I got a few laughs when I painted stuff in mechanic's school... we had to repaint our Detroit Diesels at the end of every 3 week class before the next class came in... The guys were laughing because I kinda 'cropdust' the paint on by getting 6-8 inches from the part, but waving the can by quickly in a 'flyby' so as to not get runs. I make more passes like this to get good overlap and a sufficiently wet coat to flow out. Must work ok since our engine looked good when I was done and nobody was laughing anymore...

I don't have a LOT of experience with the old Krylon, but it DOES seem a little harder to get a good slick coat than with the slower drying enamels...

Since Old Krylon has gone the way of the tyrannosaurs it's probably not going to be a problem for much longer anyway... :) OL JR :)
 

rosko_racer

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luke:

Your sugestion worked. I only had problems on a few areas on the fins where it looks hazy but the surface is nice enought for decals. Now I am just waiting for the paint to completly dry, about 3-4 more days, then apply the decals. Once those are dry I will give it a coat of Krylon Satin or Flat Testors clearcoat.
 

luke strawwalker

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Glad to help Raul! Post some pics when you're done...

You do good work!

Later! OL JR :)
 

sandmantoy

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The rate at which the catalyst evaporates needs a stable temp to give high gloss also. Sometimes it takes a long time to get everything ready for a paint session and timing your paint project will help. I paint large projects and if you paint out side and then bring it inside, like your garage you have to keep the temp and humidity about the same. Painting just before the sun goes behind the horizon will give you a temp drop and the humidity will also rise. This applies to automotive paints but spray cans are more likely do have a dramatic effect. I have painted in very cold temps and keeping the paint cold through the hardening process you can still get a nice paint job. Mid day is the best time to paint out side with low wind and low humidity make your last coats at least one and a half hours before dark when you have to cut it close. Sun light to shade will make a difference some times too. If your paint is still tacky when the evening dew starts to build up then it will harden on the out side and the gases or fumes from the catalyst will not be able to let the paint pigment settle smoothly.

There is a little more to it than that but I have seen some of this be over looked and was the cause many times.
 

hardinlw

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The hazy areas sound like blushing caused by high humidity. Basically, water vapor from the air gets trapped in the finish because the solvent evaporates before the water can.
 

sandmantoy

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The hazy areas sound like blushing caused by high humidity. Basically, water vapor from the air gets trapped in the finish because the solvent evaporates before the water can.
Better said on my last point :)
 

Micromeister

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Your both exactly correct. Humidity is the cause of such blushing.
In Rauls case, it is also being exaggerated by applying to much paint before the underlaying coat(s) have a chance to flash off the solvents giving the moisture in the air even more time to flatten out the finish.
I'd suggest reducing the number of rapidly applied color coats too a maximum of two, and removing the model to the controlled humidity of the house ASAP after spraying.
 
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