rust is cancer it will come back even if you manage to cut it out and do the fancy remove n replace trick, there 40 year old cars and been through long rainy days, moist days n what ever else. there just gonna rust on the next pannel ;)

alot of you guys mention brands like wattle,dulux.

highly non recomend i would never use cheap stuff..

all rust needs to be removed
all bare metal needs to be primed or rust-protected

Arg great info guys but painting seems like such a daunting task now,,,tho it was bad enough before ;)
I know my wags need a coat before too long, its still pretty rust free, but things like inside the holes in the cross-floor-box-sections (body cross members? whatev you call them?) have some rust that will be hard to get at without blasting.
It seems there are as many ways to do it right as to do it wrong!

D is this the link you were talking about? Ive always liked the idea of this method...if only for the fact that it would be dirt cheap and you can take your time with it...like painting your car over a few months might give you no reason to take shortcuts and only needing to prep one area at a time. But if it were that simple maybe there might be more people doing it :/

So edp youre saying just use no converters whatsoever after ensuring all the rust has been cut out? To neutralise a converter with water seems like its just risking more rust in some areas. then what...is it always nessecary to etch-prime on bare metal?

D what is it that 1000's were dipped in from factory? That stuff has done a good job of keeping many 1000's relatively rust free.

There is nothing wrong with using good old deoxidene on surface rust. I would have no worries using it on the boot lid below. Deoxidene and scotchbrite or steelwool and scrub it. It will go black but you can keep scrubbing or wipe it off and then keep scrubbing till clean metal. Then wash it off with water. Then wipe the surface over with thinners or prepwash, then go about your normal repairs.

Deoxidene wont fix rust, it will only remove surface rust.

No need to scare monger about using it the way its intended.

Here's an example, from my bluebird.

I found a few spots of what most people would call "surface rust", but when I sanded them back they started getting bigger, not smaller!

I quickly figured out the problem, so cut out the piece entirely. May not look at that bad on the painted side...




But on the other side...!




The ONLY way to fix this is to cut out the metal and replace it:

Agree wholeheartedly. ALL rust should be COMPLETELY cut out.

99.9% of people also misunderstand "surface rust'. Surface rust is exactly that... a little bit of rust colour on the outside of a piece of bare metal, that you can easily sand/blast/etc off the metal. A rust bubble under paint is NOT surface rust. It is normally the worst kind of rust, being rust that starts from behind the panel, rusts through the metal, and then starts to come out the other side & through your paint. This type of rust needs to be COMPLETELY cut out.

rust never sleeps, seems like that idea's gotten across, I think the major point thats being missed here is really DONT USE PHOSPHORIC ACID TREATMENTS UNLESS YOU COMPLETELY REMOVE & NEUTRALIZE IT PERIOD! you cant have an acid underneath a painted surface w/o some risk of it causing lifting & de-lamination of the painted surfaces above. You then need to sand it off to insure a clean & prepped metal surface thats ready to accept a layer of paint.

For example - if you acid treat then POR 15 the sh*t out of the surface prep you've given yourself the double whammy of potential paint failure. Ospho & other rust treatments are / were created for heavy industry where no one gives a crap how pretty their fishing vessel, excavator or tractor is, they just want practical application methods. A fishing vessel have what 3/8" plate steel ??? so is that going to rust thru or have problems like a car w/26 ga. steel.

Just lose the acid treatment bullsh*t altoghther & you'll all be better off, its the shortcut you dont really want to take. Ask yourself if its really worth the risk then throw that crap out of your paint arsenal!

Or if your a gambler........go ahead & use it just dont bitch when your paint fails.

some very good points on rust, never let it rest and cut it out or
make sure you phosphorise the crap out of surface rust.

OH my goodness - I just read the link to the por15 rust stuff. I have never heard that the product is recommended to be just painted over rust or a non prepped surface. If that is even remotely true, whoever came out with that should be hanged drawn and quartered.

Nothing in the world will fix up rust besides cutting it out, stripping it back.

Once you have gotten it all out, phosphoric acid (which you can get from chemical supply houses in fairly decent quantities cheaply, or for about 50 times the price from a autobarn or whatever (it's variously sold as de-oxidene, rust buster, god knows what other brands) can help. It is not a magic wand, but best guess is that it reacts with the surface layer of metal and more or less 'hogs' the metal and doesn't let the oxygen react with it, forming a sort of boundary or surface barrier to the beginning of rust. You still of course want to follow this coating with prepping, proper surface primer then the epoxy paint (for the undercarriage at any rate).

Do not EVER paint over rust. Do not ever think you can get away with less than full removal of any rust.

Do NOT leave a car in primer any longer than absolutely necessary (it is porous and will let moisture through). You see cars for sale that have been in primer for months - nothing short of sandblasting the whole darn shell that was primered will do. You'll see rust come right through before you know it.

Another thing to be careful of is galvanic corrosion. If you put a ferrous metal and a non ferrous one in contact with each other they will start to corrode one another. This can occur occasionally when hardware store screws or bolts are combined with bits of plate (alloy or something). Probably the most common place i see it is on trailers - home made ones - with angle iron frames and alloy sheets for the floor or vertical bits.

I just finished mine with rattle cans on the outside. Can't say much for longevity (thats not what i'm after anyway), but it cost $400ish, that was all materials and cans. I used a lot of cans, much much more than I thought I would. Takes some time to set it all up, and at the end of the day I wish I bought a el cheapo compressor and paint, much easier coverage I reckon, my finish is patchy. If you go with rattle cans, make sure its a hot day, the hotter the better. My best finish was on hot metal. Mind you matte black is a bit unpredictable but thats what I found out. I didn't really cut much of the old paint, just sprayed on top.