In researching why metal rusts, (Something Canadians do) I came across some interesting info on rust conversion - I've experimented with several products - everyone wants $50 a bottle for their own special product, but what seems to work is microcrystaline zink phospate. This is zink in a solution of phosphoric acid. I found a local source in Ontario, but only available by the huge drum - 500Gal and is sold by the kilo weight - $2 a kilo - maybe a gallon's worth?

I also found the POR-15 has gallon quantities -@$45 per gallon of the same stuff. Probably watered down even more. (make me want to get into the chemical snake-oil business for stupid car restorers - at those profits - $2 gets you $45)

Basically a watery liquid that you spray on rust. After drying, it leaves a white power which you rinse off with water and the zink is chemically bonded to the metal while desolving the rust.

Car manufacturers use this stuff to dip bodies before primer and paint.

Zeibart also uses it to treate underbodies on older cars before the black coating.

I also bought some other black gooey stuff based on tanic acid which also convers rust to a black-like primer. I plan to use this in the trunk.

In fact - I'm going to go do it now -


Has anyone tried anything else?
Soon....

Product called 'naval jelly' is what I'm familiar with - it blackens rust and then you paint it. The stuff is water soluble but burns like hell on your flesh if you get any on you. And the fumes will hurt your eyes, it's toxic stuff.

The zinc idea reminds me of steel hulled commercial fishing vessels where zinc plates are bolted to the hull. Then the zincs somehow 'absorb' corrosion from the steel and themselves dissolve and corrode to dust instead. You might see several 5 lb zinc plates attached to a 75' steel hull vessel.... so they gotta be pulling rust from wide radius somehow.

Maybe going to a boat marina and picking up a few smaller size zinc plates and attaching em behind headlight buckets and on rocker corners in fender wells on the 220sb can do alot of good over period of time, i dunno. But I suspect the zinc coating wears out the same as zinc plates dissolve like alka-seltzer over period of time.

Naval Jelly is phosphoric acid. Dunno if it has zinc in it or not, it may I suppose, but I do know it's phosphoric acid. And DD, the only spot on my hands it burned were a few spots where they were chapped (using it in the winter without gloves = bad idea!) The smell DOES tend to linger on your hands...

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

The zinc phosphate you describe that dries to a white powder when applied on rust sounds like the metal prep that POR-15 sells. The sell a degreaser and then a prep, then you put the actual rust blocker on. The stuff ain't cheap but seems to be very tough. I don't know if the zinc by itself would just wash off over time without some exterior sealant like paint or the POR.

It is what I use.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

Yes you would have to apply a coat or rust proofing emulsion on top.

Many make the mistake of not converting the rust surface first and the rust continues to spread under the paint - no matter how good the paint is. The zinc will also help the paint to bond better. This is a reason factory paint tends to last - the metal is dipped into zink phosphate first. You may notice if you get a chip in your new car, the rust will not start for a long time even though metal may be exposed, the zinc is protecting the metal.

A quality restoration should have a rust conversion done first. This is also true for undercoating an older car.

If you are restoring an area with bad rust, you could also pre-clean the metal with muriatic acid, neutralize and wash, then the zink.

If you just sand the metal, the rusting process will start right away, even though you don't see it yet. Humidity in the air, combined with oxygen. Ask your body shop - if they don't know what you are talking about - find someone who does.

soon...