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(Gently) removing sparay paint from plastic - restoration?

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Tramper Al

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Hi,
So, is there a reasonable method that will remove (our typically used) spray paint from plastic model rocket parts (nose cones, fin units, etc.) that were painted many years ago? My goal is to get back to a new-looking plastic surface in the original molded plastic color, if that is possible.
I imagine it would have to be a largely chemical/solvent approach rather than a physical/scraping approach, to preserve the plastic surface. Though I guess I could learn a polishing technique as well.
Thanks!
 

dr wogz

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Stay away from Acetone! :D

it also depends on the plastic, the undercoat, and probably a few other things. Sand paper & finer and finer papers to get to the base plastic.

I think a lot of us would ask .. why? Why not a quick sanding to remove most of the paint to add a new coat of paint..
 

Steve Shannon

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Almost any solvent you use has the potential of attacking the plastic as well. If you have a scrap of the same plastic you might try some Citrus Strip.


Steve Shannon
 

Tramper Al

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Huh, thanks for those trying to offer suggestions. Adding more paint is not really much help, as I have framed the question.

It depends on the nature of the paint, but with old parts you may not know. From what I understand, the first solvent to try is water, and the second is vegetable oil. And gentle scouring. When those don't work, you have to get into real solvents and certainly you risk damaging the plastic if not careful. That's rather the point. I don't know what Citrus strip is, but will find out - thanks! Mineral spirits is another I have to investigate. Paint thinners I imagine I'll have to be very careful with on plastic.

I may spray some new cones with various blotches of acrylic, enamel, Testors by brush, etc., let dry thoroughly and then experiment with methods of removal. I may also just soak cone parts in various solvent concentrations to see what I can get away with, depending on the plastic involved. I can report back on these experiments if this is useful.
 

Steve Shannon

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Huh, thanks for those trying to offer suggestions. Adding more paint is not really much help, as I have framed the question.

It depends on the nature of the paint, but with old parts you may not know. From what I understand, the first solvent to try is water, and the second is vegetable oil. And gentle scouring. When those don't work, you have to get into real solvents and certainly you risk damaging the plastic if not careful. That's rather the point. I don't know what Citrus strip is, but will find out - thanks! Mineral spirits is another I have to investigate. Paint thinners I imagine I'll have to be very careful with on plastic.

I may spray some new cones with various blotches of acrylic, enamel, Testors by brush, etc., let dry thoroughly and then experiment with methods of removal. I may also just soak cone parts in various solvent concentrations to see what I can get away with, depending on the plastic involved. I can report back on these experiments if this is useful.
Bath oil also is a very gentle paint remover for skin.
Here's a link to Citrustrip.
https://www.acehardware.com/product..._clickid=09c1a354-e108-4136-932c-2349421143d2


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Woody's Workshop

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This is something that should work, but care needs to be taken.
Soak a smooth cotton (like old pillow case) rage with Lacquer Thinner.
Lay it on one side of the fin, check often.
When the paint either gets soft (that means it's lacquer based) or starts to wrinkle and bubble up (that means it's enamel based) remove the rag and scrape with a single edge razor blade.
Don't worry if all the primer (if used) doesn't come off.
Hit up a auto body shop and ask for coarse and fine finish rubbing compound. You won't need very much.
The coarse will take off excess primer and smooth out the plastic.
Buff with fine finish to get a shine back on the plastic.
After build, apply some paste wax and buff to make it like the plastic is painted.
Good Luck.
 

K'Tesh

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I was actually able to strip a nosecone that was painted with krylon back in the 90's with rubbing alcohol.
 

Tramper Al

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I was actually able to strip a nosecone that was painted with krylon back in the 90's with rubbing alcohol.
Great, thanks! Rubbing aka isopropyl alcohol is another good one to try. I wonder if I'd get anywhere with grain ethanol? Certainly safe for plastic.
 

K'Tesh

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Great, thanks! Rubbing aka isopropyl alcohol is another good one to try. I wonder if I'd get anywhere with grain ethanol? Certainly safe for plastic.
Can't answer that. However, I can tell you that I ended up using the aforementioned nosecone for my Velociraptor downscale. By the time I was done with stripping it, it looked (except for the deep recesses of the mold's joint) as if it had never been painted at all (nor that it was over 20 years old).
 

BigDuphis

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I have plans to strip down and refinish an old rocket myself. My plan was to use a soda blaster at as low pressure as the gun will function on.
 

Tramper Al

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I have plans to strip down and refinish an old rocket myself. My plan was to use a soda blaster at as low pressure as the gun will function on.
Nice, and am now Googling "soda blaster"!

This hobby of ours features nostalgic builders of old models and a wealth of long OOP plastic parts that maybe didn't need to be painted in the first place and can perhaps only be reasonably found today in various states of paint and decal covering. I see nothing wrong with attempting to return some of these pieces to their former glory to build and fly another day.
 
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Steve Shannon

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I have plans to strip down and refinish an old rocket myself. My plan was to use a soda blaster at as low pressure as the gun will function on.
I, for one, don't want to see you refinishing a rocket while stripped down, thank you.
[emoji872][emoji872]


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BigDuphis

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Nice, and am now Googling "soda blaster"!

This hobby of ours features nostalgic builders of old models and a wealth of long OOP plastic parts that maybe didn't need to be painted in the first place and can perhaps only be reasonably found today in various states of paint and decal covering. I see nothing wrong with attempting to return some of these pieces to their former glory to build and fly another day.
Here's the one I got
https://www.harborfreight.com/gravity-feed-blaster-gun-93221.html
You can load it with plain baking soda...basically a little gentler version of a sand blaster.
 

tomsteve

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soda blasting is a great way to clean plastic parts without damaging them, but im not certain if baking soda from the pantry works good.soda blasting soda is a larger crystal size and treated with something to keep it from clumping in the pressure tank/vessel.
 

Screaminhelo

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Two options that I have used on styrene many times are oven cleaner and whitewall tire cleaner.
 

Micromeister

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Hi,
So, is there a reasonable method that will remove (our typically used) spray paint from plastic model rocket parts (nose cones, fin units, etc.) that were painted many years ago? My goal is to get back to a new-looking plastic surface in the original molded plastic color, if that is possible.
I imagine it would have to be a largely chemical/solvent approach rather than a physical/scraping approach, to preserve the plastic surface. Though I guess I could learn a polishing technique as well.
Thanks!
I've had pretty good results with Graffiti Removers which are formulated to desolve Rattle Can paints and other stuff without damaging the underlaying substrate or finish. Don't recall the product name but there are several brands at the hardware store.
Just whip on with a rag, let sit 20-30 minutes, wipe off most of the spray paint. sometimes a second application will even get the stuff left in the seams.
 

K'Tesh

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Tramper,

Please let us know what method(s) you tried, and how the results turned out. Bonus points for photos!
 

Tramper Al

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Tramper,

Please let us know what method(s) you tried, and how the results turned out. Bonus points for photos!
Will do. The grafitti-removal products that Micromeister suggested above sound interesting, as they seem to be aimed at spray paints. So then the question is the effect on the plastic. Even within that product group, they seem to range from gentle water-based cleaner to blends of strong organic solvents.

I've got an old built and painted Centuri model coming to me, with some interesting plastic parts that I hope to recover. I have been researching each of the products suggested, and will do some experiments on new plastic/paint as well. And yes pics if I get anywhere on this!
 
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caveduck

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Depending on the kind of plastic and the kind of paint, you may actually be able to just peel the paint layer off the plastic. I've done this more than once (vowing to get better adhesion the next time!). Sand-n-polish is a perfectly valid alternative, though a lot more work. Graffiti remover sounds interesting, but test carefully!
 

Lowpuller

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My experience with graffiti removal products has been something like this........

Nothing is happening, nothing is happening, nothing is happening, hey it's starting to work, OH CRAP IT JUST TOOK EVERYTHING OFF..........

Becareful would be my advice.

I still think you can't go wrong with sanding, unless they are complex shaped parts.
 

mjennings

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I haven't used it on rockets but Home Depot caries a brad called Krud Kutter (https://www.homedepot.com/p/Krud-Kutter-22-oz-Graffiti-Remover-GR226/205552884) worked great on house paint in a tub and tile that I had taken way to long to get around cleaning off. Claims to be safe on plastic. If you don't have something to test it on I'd keep the sit times short initially, and slowly work up Lowpuller alludes too.
 

Doug

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Castrol Super Clean or the purple automotive cleaner/degreaser you can get at Wally World. Works great and is biodegradable. Put the plastic parts in a sealable container and let them soak for 24 hours. Take them out and use an old toothbrush to clean the stubborn parts clean. Rinse in water, let dry, use. Then pour the liquid back into the container to re-use later.

And wear gloves when taking parts out, I've heard it can have a negative effect on skin. I just use simple latex gloves and have never had a problem.

I use it on plastic model parts all of the time.
 

buzzII

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Easy Off oven cleaner takes the paint right off, and will not hurt the plastic.
 

redleder

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Thanks again. The first Citristrip Q&A on Amazon suggests wrapping in plastic wrap overnight to hold gel against paint - so that sounds fairly gentle on plastic.
I just used citrus strip on my MDRM NC this past weekend and it worked well but did do some damage to the cone. It softened it up a lot and it had to re-stabilize. It is also made it gummy and sticky, which required other solvents to get off. There is another thread over in the techniques sub thread where a lot of folks offered up good suggestions on solvents and techniques. If I used citrus strip again I would only leave it on long enough to start seeing the bubbles and then scrap it off immediately. Anything longer is chewing on the plastic. See pictures of my NC after stripping, after heavy buildup primer and then painting again. It looks better than it did originally because all of the original NC imperfections are completely gone now.

Jarod















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neil_w

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Wow, terrific final result. Is that black night metallic?
 

redleder

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Wow, terrific final result. Is that black night metallic?
Dupli Color Chrysler Black Pearl. Looks even better in real life. The iPhone struggled getting the white balance right. It has a very deep look to it and has a ton of sparkle in the light.

I have pretty much switched to Dupli Color car paints. They work very well and I can prime, sand spray and top coat back to back about 10-30 minutes apart without the paint screwing up or running/sagging. Their build up primer and sealer are awesome for rattle cans. When you sand, dust is actually made instead of little gum ball of paint.

J


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