I am using Krylon spray cans to custom paint my diesel fleet. I know the purists will scoff and tell me I should use an airbrush, but I’ve had nothing but problems with them in the past and have gotten excellent results with the spray cans until my last effort. For some reason, the finish crackled up almost as soon as the paint was applied and I have know idea what I did differently on this last shell. I am going to have to sand down the scaley finish and retry but I want to avoid a repeat of this problem in the future. I’m not sure what I did differently but I suspect one of two causes. One possibility is my primer coat was applied too thinly and did not provide a good enough surface for the finish coat to adhere to. The other may be that in my haste, I may not have shaken the can enough. I have seen spray paint crackle like this in other circumstances unrelated to MR but I’ve never understood why it would do this and not do it on another identical surface. I’d appreciate any insights anyone can offer as to why this might have happened.
One thing I do before I use spray paint, I put the can of spray paint in warm water for five minutes or so and then I shake it up. It makes everything flow better.
Bryan
sounds like either you were painting in the cold or the paint was cold, make sure everything is warm, like room temp. Bryan’s suggestion was great be sure you try that. also make sure it is shaken up well. also be sure the model is free of dirt and greese from fingers
How long did you wait between priming and painting the shell? It is possible that the paint reacted to the primer, and caused the crakel finish.
I would agree with Jon2 on that, since it just happened to me the other day with krylon on a wood shelf . I painted the color almost imedeietly after using a krylon primer and it came out like that new wrinkle fini***hey put on tool cabinets now. Also, watch out for the type of plastic you spray krylon on…its rare but every so often I come across some some bizzare plastic that melts through when used with krylon. At least you have somthing to sand down and repair! Other than that, I LOVE Krylon brand spray paint and use it far more than my airbrush.
Suggestions:
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(You probably already do) Make sure the model’s surface is clean. Prior to painting, wash with soap and water, scrub with a toothbrush, and the clean with a "prep cleaner. Contaminants on a model’s surface can react to solvent based paints (been there done that).
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After applying the primer coat, allow the transfer solvents in the primer to thoroughly evaporate before applying the topcoat. Depending on temperature and humidity, the times will vary. If you can smell it, then they’re still evaporating.
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I haven’t used spray cans in years, but make sure that you’re using lacquer on top of lacquer or enamel on top of enamel. If you spray lacquer on top of enamel, the lacquer will instantly attack the enamel. Sometimes the same company making the spray paint offers them in both, enamel and lacquer versions. Verify that the primer and topcoat colors are the same type.
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Certain types of plastics are not compatible with strong solvent paints like Krylon. There are acrylic based spray can products available on the market.
Don’t worry about the airbrush guys criticizing (I’m one of them). They’re just trying to help. But If you wi***o stick with spray cans then everyone should respect your decision.
Thanks to all who replied. I don’t think the problem is the type of plastic because it is the third shell from the same manufacter and same model that I have used in the past. It is also the same combination of primer and finish coat that I used successfully in the past so I don’t think it is a compatibility issue. Also, the primer had been on the shell for about a week before I applied the finish coat so I don’t think that was the problem. The temperature could be a problem. The can had been on the basement floor for some time. I’ll make sure it has been stored in a warmer area before the next application. I just hope now I can sand down the crackle finish without ruining the surface of the shell. It is going to be tricky.
Temp. related sounds like. Either that or old paint. Sometimes paints seperate if they sit on the shelf a long time. Only thing to do is throw them out.
I didn’t want to create another spray can problem… so I will post my in here.
I have a Testors spray enamel, gloss yellow, and when I do spray the handrails that I bought from Atlas as spare, the paint would not go on evenly. It would gather in one area as drops of paint. Bubbles would form in the corners. I am not sure why it does this. The handrails are all clean from the bag, since I would expect the items to be sanitized already.
thanks
Don’t sand it off, you’ll only mess up the details on the shell and you still won’t get the paint out of the crevices. Use a stripper to remove the paint.
As the paint is still relatively fresh, you could try 99% isopropl alcohol, brake fluid will also work. use a medium soft toothbru***o scrub it off. Then wash and do the usual prep and try again.
I agree with stripping the paint, do not sand it. The stripper or brake fluid are great ideas, and work great. But both make the plastic a little soft, so try not to scrub to hard, and use gloves or you will leave your finger prints in the soft plastic. (been there, done that).
But anybody know why the spray paint would gather in one area and not spread evenly? It also has bubbles forming in the paint when I do spray it. I did not sand the handrail, carfully took it out of the packaging (didn’t touch the handrail, just the spruce tree) that Atlas sent and sprayed it.
The instructions said not suitable for polyethylene… are they made of polyethylene… there are a bunch of plastics out there, so I have no idea if they are.
I have the metallic silver and it is also an spray enamel, but it goes on very nicely to the handrails and it also dries quickly, but the yellow doesn’t seem it wants to cooperate.
Your problem is simple.
Enamel does not mix with Acrylic, it with crackel instantly. Make sure your primer and color coat are the same type of paint. Always test first on a scrap sheet. It will crackel or orange peel on any surface, not just plastic.
Fisheye, crackel / orange peel, blush and frogging (webbing from one side to the other in a 90 degree location.} Blush can come from painting when the humidity is over 85%, webbing comes mostly from too much paint in a 90 degree joint.
All great input thus far…
modelmaker51 hits the nail on the head “don’t sand…strip”
Another great comment came from gvdobler, be sure all paints are compatible!!!
Also “clean from the bag” may not be “clean”! Always wash everything before painting!
Finely one more thought…I feel that a “tack coat” (a very thin coat that is allowed to dry before any additional coats) as a first step will assure a better paint job, in general.
i used to do model cars before model rail roading ,and one tip i found usefull ,is to use a fine grade sand paper to scuff the plastic up a bit .the roughness helps the paint cling ,dont worry the paint will dry evenly and you wont be able to see the marks .now understand ,were talking a fine grade ,and a little scuffness ,no gouges .i read this tip off one of testors tips that came with there model kits .also use thin coats at first ,and let them completly dry ,before adding another coat .
The new handrails right out of the bag are most likely coated with a mold release. Older delrin/ engineering plastic exposed to the air will usually take the paint- the mold release has dried and part evaporated. Wash any parts before painting.
Any of the engineering plastic details, especially handrails that are flexed on occation, should be painted w/ acrylics not solvent base paint. Many of my handrails painted w/ solvent paints are chipping like crazy. The acrylics will flex and stay.
Bob K.
This is in response to the second guy asking a question:
The new handrails are made from acetal plastic, most model paint doesn’t stick to this for long, not even acylics as mentioned. Use Tamiya racing paint (the stuff RC car guys use for their car bodies), or get some bumper primer from NAPA (the stuff for plastic bumpers). But, it sounds like maybe you got a bad can of paint.
Also, this is what’s called a hijacked thread, asking a question in another persons thread. It is OK to start another thread. Your question, although similar, is not the same as what jecorbett was asking. This keeps everything from getting mixed up as far as responses go.
Glenn
You might want to try a new kind of paint from Krylon called “Fusion”. Unlike a lot of aerosol paints, the Fusion line is designed specifically for adhesion to plastics, and you probably will have much better results. It’s available at most of the “big box” stores.
Good Luck.