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Inconsistent results with Krylon gloss paint

  • Rod Thomas
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3 weeks 4 days ago #8652 by Rod Thomas
Hey guys,

I'm wondering if anyone else has had the following problem. Recently, but also in the past, I've had poor results with Krylon Gloss black and Krylon Gloss Crystal Clear. I shake the cans up like crazy as indicated. Then I spray as indicated. When the paint or the finish dries, it is inconsistently glossy. There are matte areas and glossy areas. Clear areas and cloudy areas. I shake the can twice as long, right side up, upside down, turning it as I go, and try again, with similar results.
I have only had this problem with gloss black and gloss finish. Any thoughts or suggestions?

Rod Thomas

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3 weeks 3 days ago #8653 by Boris Katan
Haven't had this exact problem, but variability in appearance of paint is common. Humidity, spray distance, temperature and spray speed of motion all effect spray paint results.

When I get paint job that is less nice looking than I had hoped for, I either go for another coat, or remind myself that most folks will see the rocket from a distance at high speed.

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3 weeks 2 days ago - 3 weeks 2 days ago #8654 by Daniel Tyszka
I've run into various versions of problems like these from time to time with "rattle can" paints and clearcoats (not necessarily just Krylon, but more recently with Rust-Oleum as well).

A few years back, I ran into a fogginess problem with Krylon clearcoat. Interestingly enough, the fogginess seemed to come and go, apparently based on the temperature of the clearcoated model and/or whether or not the finished model was exposed to sunlight(!) The fogginess seemed to happen mainly on models with multiple coats of clearcoat over decals, toward the later coats. In some cases, I think the fogginess may have been a surface effect, where an extra ~partial coat of clearcoat ended-up getting applied over an area that was coated earlier during the same spray operation and still wet, when some additional mist ended up deposited on the surface. When dry, this extra partial coat was rough and dust-like, and foggy or partially opaque. However, I found that when I allowed the clearcoat to fully dry for several days, I could buff-off this rough extra layer with a soft cloth and some Windex, and restore a high gloss finish. Not sure whether I was just removing the top layer, of if the heat generated from the hand-buffing was actually solving the problem. (I had to rub pretty hard with my fingertips, and there was noticeable heat generation, so...) But it worked. However, as I noted, the fogginess seemed to come and go after that, returning when the model sat in the sun, then going away once it cooled. Weird effect if you ask me. But eventually the models went back to looking glossy on their own, without additional buffing.

More recently, I've run into problems with Rust-Oleum gloss paints, where the atomized droplets of paint seem to be large with some cans / nozzles, and end-up glomming together on the painted surface in a weird pebbled pattern, sometimes resulting in smooth glossy areas adjacent to less glossy textured areas. In these cases, the pebbled areas also seem to be excessively sticky and never fully cure or dry-out. Might be a paint quality problem, or a problem with the spray nozzles...Don't know. But you usually find-out after the 2nd coat after you've used up a good amount of the paint so that it's too late to return the can. And the only effective solution is to try to remove as much of the defective coat as possible by aggressively sanding...Just smoothing-down the troublesome areas and recoating doesn't fix the problem, as the sticky areas often end-up looking goofy on the recoat.

I've read some stuff about these types of problems on The Rocketry Forum. Some folks caution that these problems seem to happen more often when painting in conditions of high humidity. So if it's too muggy and sticky out, you might want to save painting or clearcoating for another drier day.

One additional suggestion with gloss paints. When coating a model, use multiple light coats (as opposed to fewer heavier coats), paint evenly and deliberately until you've just coated the entire area to be painted, trying to keep a uniform distance between the nozzle and the model. (Avoid too large a distance between can and the painted surface, as the atomized paint can start to dry out before it hits the surface, preventing the droplets of paint from melding together on the surface, and resulting in a rough or dull appearance.) Then STOP and let it dry for the 24 or 48 hours the can recommends. (Longer if it's humid out.) Avoid the temptation to try to recoat an area that is still wet but partially dry during a spray operation. This almost never ends well, in my experience...You end up with a poor or inconsistent finish, or with too thick a coat that runs or never fully dries. Better to let it fully dry, lightly sand, then hit it with another light, evenly applied coat. Also, make sure prior coats are FULLY dry before recoating...You can't cheat on the recoat times.

Hope this helps. Paint problems can quickly become annoying, as they often end-up pacing your builds...especially when you're trying to make your models look really good.
Last Edit: 3 weeks 2 days ago by Daniel Tyszka. Reason: typo corrected; additional content added

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