painted over a small rusted rock chip.

P

pman626

New member
had a small rock chip with a little bit of rust at the base, less than 2mm in size.



i cleaned it with degreaser to get whatever dirt and grime out, but didn't get rid of the little bit of rust.

since the chip is small, I didn't think the rust was a big deal, so I painted directly over it with a few dabs of touch up paint.



I'm thinking as long as the spot is fully sealed by the touch up paint and doesn't crack, it shouldn't rust again, right ???

as long as water isn't getting in there, there's no way the rust could spread.



anyone have long term experience with this in regards to rust coming back in the exact same spot ?
 
[...anyone have long term experience with this in regards to rust coming back in the exact same spot?]



Paint is porous (water-based and even solvent-based, given time) moisture will reactivate rust and cause it to spread.
 
TOGWT is correct.. rust never sleeps.. you should have used a bit of sandpaper to remove the rust, then a dab of primer, then the touch up paint.
 
I can *usually* get by with merely treating the rust with a rust converter (pretreating with something acidic helps though) and then applying the touchup...but yeah, unless you do something to actually remove or neutralize the rust it's *always* gonna come back.
 
Agree with Accumulator. It would have been wise to put some rust converter on that spot.



Or you can just make sure your car is made out of aluminum like mine is! :D
 
assuming, ideally, there is no moisture or oxygen, rust will continue to grow?



I find that hard to believe. Then again, i've never had much experience with rust.



but some people do say that for tiny rock chips like this, sealing it with paint is fine.

How long would you say before the rust breaks through the surface of the touch up spot ?



Has anyone here taken this shortcut for tiny chips, and NOT had it rust for 10 years?





also, I'm assuming that not everyone can get all the rust 100%. So isn't primer also a cover-up, as paint is?
 
Its not about the rust breaking through the surface and making you re-touch it up, its about the rust spreading or going through the whole panel while underneath and becoming a larger problem before you realize.
 
pman606- I've been dealing with this issue since the mid-1970s. I've had bare-metal chips that stayed OK, I've had only-rust-converted chips that stayed OK, but I've *NEVER* had "normal paint applied over rust" chips that stayed OK.



Rust converters (at least the good ones) kill/neutralize/seal/arrest/"fix" the rust and also act like a primer. "Regular" primer is very porous and doesn't work over rust. "Rust sealant" products like POR-15, Rust Bullet, and (probably my fave) Eastwood's Rust Encapsulator will do what you want (namely act like a miracle primer) but results can vary, perhaps with the skill/meticulousness of the user.



Here's how Eastwood's stuff would work (and I've used it and it did work for me):



-Clean out loose rust mechanically (I like fiberglass filament "pens")

-Apply rust converter

-Apply Rust Encapsulator

-Apply paint that's compatible with Rust Encapsulator (enamels work better in this regard than lacquers)
 
thanks for the advice.



I think i'm going to scrape off the touch up paint, and do it over.



I'm reading conflicting information on the web.

phosphoric acid = converter, or just a remover?



I found stuff like naval jelly, which contains phosphoric acid, but is not considered a converter.



but other places say phosphoric acid is a converter.... ?
 
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