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  #1  
Old 06-17-2021, 02:30 PM
coopwyo coopwyo is offline
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Default Static Electricity??

Has anyone ever had primer and/or paint craze on a large plastic nose cone (like Der Big Red Max)? I sanded off the seam and when I applied the primer, it crazed over the whole nose cone. I wet sanded it and got everything smoothed out, but then when I sprayed the paint on, it did the same thing. Did I create static electricity on the nose cone by sanding it? Would that cause the paint to craze? I've never had this happen on a small nose cone before. Any advice on painting a large nose cone would be appreciated.


If this has been addressed in a previous post, please refer me to that.
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  #2  
Old 06-17-2021, 06:16 PM
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dlazarus6660 dlazarus6660 is offline
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Did you wipe it down with alcohol and let it dry?
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Old 06-17-2021, 06:55 PM
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Or even use Acetone or MEK to wipe it down; note those will soften the plastic a bit and allow top coat or primer to "bite" the plastic.
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Old 06-17-2021, 08:49 PM
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What primer did you use? If the primer had a heavy or strong solvent base, it might be enough to soften and maybe craze the plastic surface. Have you used this same primer on smaller plastic cones with success?

Lacking any smoking guns, sometimes a given paint (or primer) will do some goofy things based on humidity levels, slight variations in materials makeup, etc that causes effects like this.

But...if this IS a new primer that you have never used on plastics, it might be the solvent levels in primer.

GH (who has already responded) could give some good background on solvents and their effects on various plastics.

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  #5  
Old 06-18-2021, 11:46 AM
coopwyo coopwyo is offline
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Thanks for the responses. I used Rustoleum's filler primer, and have never had that problem with it before. I did not wipe the nose cone down with any kind of solvent prior to painting it. I did wash it with soap and water though. I've never had that problem before on any of the smaller plastic parts I've painted. It's been hot here, but very low humidity, so I figured it was the perfect time to paint it.
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  #6  
Old 06-18-2021, 01:46 PM
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Your profile does not say where you live. From your handle, I assume Wyoming. I think temps are too high to paint. I live in northern Colorado, and I have had issues painting a week ago in temps near 100°. I was using Rustoleum, and never have issues.

The paint looked like it had dried on surface, but tiny bubbles appeared, leading me to believe solvents we’re trying to escape, up thru paint that had prematurely started curing. I won’t try again until temps drop down to 70s.
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  #7  
Old 06-21-2021, 09:50 AM
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afadeev afadeev is offline
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Quote:
Originally Posted by coopwyo
Has anyone ever had primer and/or paint craze on a large plastic nose cone (like Der Big Red Max)? I sanded off the seam and when I applied the primer, it crazed over the whole nose cone. I wet sanded it and got everything smoothed out, but then when I sprayed the paint on, it did the same thing. Did I create static electricity on the nose cone by sanding it? [...]I used Rustoleum's filler primer, and have never had that problem with it before.


I've observed quality control on Rustoleum and Krylon paints getting progressively worse over the years. One of the side-effects is variability in drying times.
Another is occasional and unpredictable crazing/alligator-skinning of the paint layers.

The only solution that has worked for me is sanding the entire problematic coat of paint/primer off, entirely. Then re-spraying with a product from another can, or another paint brand altogether.

For plastic nose cones, plastic adhesion promoter (like the product below), improves paint application and durability:
https://www.amazon.com/Dupli-Color-...0007UAXJQ&psc=1


HTH,
a
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  #8  
Old 06-21-2021, 06:17 PM
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I used to spray Rust Oleum for RC paint and occasionally for rockets.
It's good for RC as the original formula is fuel proof to 50% raw nitromethane.
It has gotten VERY inconsistent unfortunately.
I have switched back to expensive hobby brands due to those always being consistent.
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  #9  
Old 06-21-2021, 07:16 PM
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Quote:
Originally Posted by coopwyo
Thanks for the responses. I used Rustoleum's filler primer, and have never had that problem with it before. I did not wipe the nose cone down with any kind of solvent prior to painting it. I did wash it with soap and water though. I've never had that problem before on any of the smaller plastic parts I've painted. It's been hot here, but very low humidity, so I figured it was the perfect time to paint it.


I've had issues with Rusoleum primer melting plastic nose cones. I liked the primer - it sands well and gives a good finish, but I stopped using it due to it being unfriendly to plastics.

I've had good luck using Krylon Industrial primer. It's not cheap, I need to buy it by the case, and the shipping costs are horrid. But I like the way it works.

I get mine here:
https://www.globalindustrial.com/p/...sandable-primer
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  #10  
Old 06-21-2021, 08:37 PM
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ghrocketman ghrocketman is offline
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If you shoot the primer on in THIN layers it will not craze the plastic, it will just BITE into it properly.
Thick coats will melt/craze plastic, just like dope will.
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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !
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