Polyurethane bumpers, need advise

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PostPosted: Mon Aug 26, 2019 9:05 am
That particular one is fairly simple with a methylene chloride active ingredient. You just use water to stop it's action which is what is stated on the tech. data sheet. Any time you are using a stripper always look up what stops/kills it's chemical action. That is always provided on the product/tech sheet. Most "neutral" pH strippers just used water to stop them. Some strippers have an alkaline activator so you must use an mild acid like vinegar to stop them. Acid activated strippers are rare and may require specialized solvents to stop them.
On any type of plastic I like to stop the stripper and still wash again with some Dawn in warm water, completely dry, and then start the final sanding/removal.
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PostPosted: Mon Aug 26, 2019 9:44 am
DarrelK wrote:That particular one is fairly simple with a methylene chloride active ingredient. You just use water to stop it's action which is what is stated on the tech. data sheet. Any time you are using a stripper always look up what stops/kills it's chemical action. That is always provided on the product/tech sheet. Most "neutral" pH strippers just used water to stop them. Some strippers have an alkaline activator so you must use an mild acid like vinegar to stop them. Acid activated strippers are rare and may require specialized solvents to stop them.
On any type of plastic I like to stop the stripper and still wash again with some Dawn in warm water, completely dry, and then start the final sanding/removal.


Thanks I didn’t think about a tech sheet for a stripper, duh. Is the plastic safe aircraft stripper no good? That’s all that I have available local.

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PostPosted: Mon Aug 26, 2019 1:36 pm
Yeah, you'd probably be okay as long as you remember....STOP at least a couple paint layers short of the actual plastic. Most of those strippers are Methylene Chloride based as well. They also combo those up with alcohols and acetone as co-solvents. All of that combines for melted/disfigured surfaces. The key is stopping before you hit raw plastic.
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PostPosted: Tue Aug 27, 2019 6:55 am
Thanks man. I’m currently searching for a good replacement bumper but if I can’t find one I the next few days I’m going forward with what I’ve got.

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PostPosted: Tue Aug 27, 2019 8:29 am
Yeah, those old bumpers are down right collectible now. I feel your pain. Gt tailights on the old Pontiac Fieros were once a few hundred bucks a piece. Saw a set go for 2 grand the other day.
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PostPosted: Tue Aug 27, 2019 4:12 pm
That’s insane man. A few years ago the 3rd gen camaro were all over the junkyard now finding parts is difficult. Don’t get me wrong I can find anything online but the prices are crazy for decent parts.

Any advice on “cheap” products to repair a small tear and a filler method? Is there a welding kit that isn’t crazy? I’ve found a few for $150ish. I’ve also found the small 2 part epoxy bumper kits and evercoats polyflex.

Ive also searched but haven’t found any answers as to the difference between the bumper specific epoxies vs plastic repair epoxies you find at Walmart like the jb weld products. I’m definitely buying an automotive designed product but I’m curious as to why they’re so expensive in comparison


:::edit:::


I just used the stripper on the bumper. There’s cracking in this one too but nowhere near as bad. I also haven’t attempted to sand any out yet. I kept a wet rag and wiped the stripper off the exposed bare polyurethane.

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PostPosted: Tue Aug 27, 2019 6:24 pm
You are making it too hard....okay, if you were looking at the Evercoat Polyflex let me turn you on to something that is not only better but usually cheaper.... that would be USC's Body Icing,, this is it.... https://www.tptools.com/USC-Icing-Finis ... O8QAvD_BwE
As for repairing a tear....welding is okay but you can get by with either simple bumper repair kits (go to http://www.polyvance.com and see what they have) or something like this...
https://www.amazon.com/IC-2000-20-45-Ru ... W6PDC6THYA
That is a rubber toughened super glue. It will stabilize minor tearing and then you can fill up with the Body Icing. You usually can find it at local hobby shops.
Oh, and I almost forgot....buddy of mine was over at Polyvance shopping and picked up one of these....
https://www.polyvance.com/Airless-Welders-1/5210/
He said he has used it on several types of bumper materials and has gotten good results. It is a very simple style of welder but hey, if it works, it works....
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PostPosted: Wed Aug 28, 2019 3:27 am
The tear I’m worried about is at the very bottom of the front bumper, that’s why I thought welding would work better for it. Similar to the pic but at the bottom but much smaller, about 1”-1.5”. And yeah I like I said these bumpers make me nervous. I see too many with bad repairs and paint that doesnt hold up.
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PostPosted: Wed Aug 28, 2019 8:40 am
If that is the case, yes, welding would be better. Welding allows for homogeneous and uniform blending of like materials. They will expand/contract at the same rate. When you see bad repairs it's usually a lot of regular bondo type products or guys assume they are working with fiberglass, etc., putting in rigid or semi rigid repair materials. Honestly if a tear is like the one pictured ordinarily I'd be pitching that cover. But, yours doesn't sound that bad to me....
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PostPosted: Wed Aug 28, 2019 1:32 pm
Definitely not that bad I just showed that pic because it’s an “open ended” tear so there’s going to be a tendency for failure with just epoxy I think. Mines at most 1.5”, maybe less than 1”.
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