Treating/Curing pitted metal before paint

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Old Feb 26, 2023 | 09:22 AM
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Rallye469's Avatar
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Treating/Curing pitted metal before paint

Any tips on how to treat pitted metal on the body before painting epoxy?
I have a few bigger areas(shown) but also a lot of areas with tiny spots…just want to treat it all.
I’ve heard good and bad about Ospho and other rust converters…Any tips?
thanks.




Old Feb 26, 2023 | 09:30 AM
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I have only used Ospho for 35 years. I have not had any issues with it if used as per instructions.
Old Feb 26, 2023 | 11:46 AM
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The top pic shows a spot I'd treat with the traditional materials. I use PPGs DX579 followed by DX520 (or DX501).

The rust pits are different. If you use the above method it's possible to trap the chemicals in the pits which is not good. The best way to deal with pits (and the only way to get all the rust out) is with some kind of media blasting. I use sand.

Once blasted and the rust is completely gone the metal can't get any cleaner, and no metal treatment is required. Just epoxy prime, let dry and then fill them.

Good luck
Old Feb 27, 2023 | 06:04 AM
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Originally Posted by Rocketguy
The top pic shows a spot I'd treat with the traditional materials. I use PPGs DX579 followed by DX520 (or DX501).

The rust pits are different. If you use the above method it's possible to trap the chemicals in the pits which is not good. The best way to deal with pits (and the only way to get all the rust out) is with some kind of media blasting. I use sand.

Once blasted and the rust is completely gone the metal can't get any cleaner, and no metal treatment is required. Just epoxy prime, let dry and then fill them.

Good luck
This is solid advice.

Ospho, as another comment mentioned, does work relatively well in a pinch, but epoxy on clean bare steel is always best. You can get a hopper style sandblast gun at harbor freight for less than $20. It's handy to have around for lots of little jobs.


Old Feb 27, 2023 | 08:04 PM
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Thank you guys.
Looking into blasting those deeply pitted areas.
👍
Old Feb 28, 2023 | 09:58 AM
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I've used a "spot blaster" effectively on areas like your showing. Media is confined to a small area and mostly recaptured.
Old Mar 1, 2023 | 04:48 PM
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I got a portable unit from Harbor for less that 40 bucks.
happy with it…but it used a helluva lotta sand to get it all done.
But I feel much better about it now.

I’ll probably treat it as well.



Old Mar 1, 2023 | 05:25 PM
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Originally Posted by Rallye469
I got a portable unit from Harbor for less that 40 bucks.
happy with it…but it used a helluva lotta sand to get it all done.
But I feel much better about it now.

I’ll probably treat it as well.


Looks good. I wouldn’t treat it with anything. That’s a good clean blank slate to get some epoxy primer on before flash rust sets in. Wipe it with prep cleaner or acetone and shoot it. Then do whatever bodywork you need to do after that. If you wanna take it one step further, I’d pull that glass.

In the future you can take a clean shop vac and hold it opposite your blaster to recapture most of the media for re-use.
Old Mar 1, 2023 | 08:13 PM
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That’s a great tip. Will do next time.
I definitely will be pulling glass…just not yet.
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