Paint Wrinkled

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1974_Trident

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I applied the clearcoat to my rocket today with disastrous results.

Background: This is the Aerotech G-Forge I am building. I applied the two coats of color two weeks ago. I was planning on using the decals so I waited five days after spraying the color to apply the decal which I ended up not liking and removing anyway. Today I decided to spray the clear coat. After spraying the first coat my kerosene heater ran out of fuel. I waited almost an hour to apply the second coat and by that time the temperature in my garage had dropped to about 25 degrees f. I thought it might be a good idea to move the freshly painted rocket into my basement which is a nice balmy 55 degrees f. and almost immediately the paint began to wrinkle.

Has anybody ever heard of this before? Was it the sudden temperature change or did I do something else wrong?

The paint is ACE Hardware store brand which I've been told is made by Krylon and just relabled. The instructions say to recoat within two hours or wait five days to avoid wrinkling.
 

RangerStl

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Looks like the classic Lacquer over enamel problem.

The 2 hour or 5 day recoat time of your color coats indicates enamel (current formulas are Vinyl Alkyd Enamel).

I'm not aware of any clear enamels, just acrylic lacquers. Lacquer paints cannot be applied over enamels or you get the results you see now.

There are water-based polymer finishes that go well over enamels like "Pledge, with FUTURE Shine" floor wax (acrylic finish) or McGuires car finishes, Nu-Finish...

Some use Testor's Gloss Clear, but it starts out a little yellow and gets worse with exposure to UV light (like the sun).

Search around here and on www.rocketryforumarchive.com for more paint wrinkling discussions. Some are funny, most are really unfortunate :( but all are informative.
 

troj

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Nick gave you the most important information -- incompatible paint.

Temperature, however, was also not in your favor.

In addition to ambient air temperature, you want to let the item being painted (as well as the paint) get to within the application range specified on the can. 25F is awfully cold to be applying paint, especially spray paint, and it will affect its application.

-Kevin
 

rocketsmith

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The paint "flashed" on the outermost layer and trapped solvent. When you warmed it up, the solvent tried to escape and formed cracks and wrinkles.
It will happen every time if the temperature fluctuates like that.
 

rockets2000

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The paint "flashed" on the outermost layer and trapped solvent. When you warmed it up, the solvent tried to escape and formed cracks and wrinkles.
It will happen every time if the temperature fluctuates like that.
I had the same thing happen with clear enamel (Rustoleum) over white Testors enamel. I painted in the garage (~40 deg) and brought it in the house to dry, and within seconds of bringing it into the warmth it started to wrinkle. Now I know why. :)

I still don't know why the other colors didn't wrinkle...
 

blackjack2564

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I have sprayed rockets in a cold environment [snow on the ground]and gotten away with it. BUT I used a few cold weather painting tricks.

Heat the can of paint in fairly hot tap water for 10-15 minutes. Keep the rocket at room temperature till the last minute, take into paint area[ garage or outside]spray it and immediately bring it back to warm area to dry.

Heating the paint will cause the volatiles to flash off immediately rather than get trapped below the hardened surface, where they can lurk and wreak havoc.

You cannot do this IF the temperature is below freezing, [include wind chill]
AND if the dew point is within 7 degrees of the temperature. If it is, moisture will immediately begin to form on the project and form blushing or be trapped in the spray mist, either will ruin the job.


As I would always tell my men on the job.....99% of the time, read the label it will tell you what you need to know.
 

1974_Trident

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I have sanded and repainted the entire front section of the rocket. I sanded down to color and to primer in some parts that were wrinkled. The wrinkling was confined to the front end of the nose cone and around the back end of the body tube. I doubt the wrinkling is caused by incompatibility of paint, both color and clear coat ore from the same line in the same brand. Actual cans of paint used are shown below.

When I repainted the entire section of the rocket and after a half hour of drying in a rather temperature stable environment the front end of the nosecone wrinkled again. I did notice while spraying that the front end of the nose cone gets much more paint than the rest of the rocket because of the spray kinda wrapping around the cone as I'm painting. The section that keeps wrinkling gets almost an entire coat with each pass, which means the paint is going on about 10 times as thick as on the rest of the rocket. I'm venturing a guess that the excess solvent is soaking into the mostly dry but not quite cured paint beneath and causing it to expand and wrinkle.

In the two days since I last painted this part of the rocket the wrinkling has mostly settled, to the point where I am satisfied with just clear coating over it and living with it. I have to just modify my technique from here on.

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