Bodywork[rust] Question

72 four door · 02-26-2003, 04:50 PM

Hi all can someone tell me what the best way to eliminate rust on the roof of the car. Its about 6" wide and there are a few spots The rust is not thru but has eaten away the medal pretty good. I was going to grind down and putty, Prime and sand apply putty coat[ [scratch filler] and prime and paint Is this right ? or should i sand blast? And then grind? Any help on this would be greatly appreciated.

HawgRyder · HawgRyder's Garage

Any place on mine that had more than just a tiny spot of rust got treated with a "rust killer" sold by the local auto parts store.
It bubbled and turned the metal a light sandy colour...so I guess it worked....time will tell.
As to the rest...I would go with the best type of filler you can....I prefer fiberglass myself...but it's tough to work with to get it smooth.
The final pass in my case was with glaze putty (spot putty) to get the last indentations.
Bob

RonMaxwell · 02-26-2003, 05:46 PM

paul,

grinding won't get it out of the pores, sand blasting would work but it is hard on the surface. the best thing is the stuff you can buy from the eastwood company por 15, it actually converts the rust into some other chemical composition. it becomes black and hard as epoxy. i have also used the rust converters you can buy at the local auto stores , they work on the smaller spots. then apply your glaze.

Ron Maxwell
30 years of restoring

72 four door · 02-26-2003, 05:58 PM

Can you aplly glaze over por-15?

john70t · 02-26-2003, 06:23 PM

No. POR15 shouldn't be used on any surface that will show because of it's characteristics.
I think of it as a plastic paint. Great for making a sheath coating over pitted, rust treated metal like a frame rail, but it really has lousy binding characteristics to anything other than the above. Nothing sticks to it and it doesn't stick to anything without texture. I do like the fact it doesn't let any moisture through.

If the rust is a bubble poppping up through the paint, one way to treat it is to mask off the whole area and take it down to bare metal, neutralize the rust, fill with bondo/weld patch, polyester primer seal, sandable primer, match paint and clearcoat.
By then doing the whole car seems almost as feasable.

Once rust has popped through, you know there is a film of it runing as fast as it can underneath the paint over the entire area and eventually, so you may be looking forward to saving a few "k"s out of the alphabet soup.

You might want to sand the area with 120 grit to take off as much as possible to get to the stuff activly eating the metal.
There's stuff called Marhyde converter that changes it to primer- but I've used it, and then sanded the top layer off to find fresh rust underneath.
The Metalready from POR15 is a good etcher to disolve rust, and has great zinc phosphate to protect the surface, but I'm not sure if it actually chemically converts it.

Chuck Moreland · 02-26-2003, 08:20 PM

There are a number of rust converter/nuetralizer products on the market. Rust Mort is a brand name that I've used with good results. I've also used por15 Metal Ready.

I think these products are similar, but they are not the same. However they do work well on surface rust. If you've got serious cancer you may need to cut away till you reach good metal, then weld in a new panel. Less extreme is to sandblast, then treat with Rust Mort.

The right course of action depends on how deep the rust is.

Mukilteo911 · 02-27-2003, 01:41 PM

More about the Por 15. I bought a car that was really trashed about 2 years ago and have used the poor 15 on it in rusty areas. It has done very well, no rust.

Here are my suggestions using it.
1. Remove all paint and putty under it so it is painted on metal. Use metal ready on all smooth metal.
2. Clean surfaces with the por thinner before painting. Don't use alcohol, it ruins Por's grip on the paint.
3. Before applying second and third coats, give it a quick sand with high grit and then clean with the thinner.
4. Before puttying or painting over it you must use the Por Primer Tie coat. It allows other paints and fillers to stick to the por 15.

In areas that do not get sunlight UV, you can use the clear por 15 so you can monitor the surface. I did this on a gas tank rebuild and I can see through the paint that the rust is not coming back. I love it.

I have asked the company about painting my whole car in it and between all the metal body parts like the rockers, door jams, window posts and they say it should work fine as long as I used the Tie coat on the exterior before the final coats.

I have 1/2 of the car covered in Por15 right now on my way to 100%, then comes a new paint job.

Hopefully I will have a anti rust car.

72 four door · 02-27-2003, 04:32 PM

Ok thanks for that bit of info on the Tie coat, Is that also made by por-15?

john70t · 02-27-2003, 11:42 PM

I did somewhat the same thing as Mukilteo911( only not with the same enthusiasm) with the trunk, interior, and wheelwells and underside.
Many many weeks of painful scraping loose undercoat, fixing surface rust (and patching several holes). I also filled in the dirt trap/rust hole in front of the rear wheels with expando foam(3x max!), fiberglass filler and then POR15.

Mukilteo911 · 02-28-2003, 10:28 AM

Also dont forget the por putty, very helpfull stuff.

kenrinc · 02-28-2003, 10:43 AM

[QUOTE]Originally posted by RonMaxwell
[B]paul,

grinding won't get it out of the pores, sand blasting would work but it is hard on the surface. the best thing is the stuff you can buy from the eastwood company por 15, it actually converts the rust into some other chemical composition.

----

POR-15 does not convert rust! It starves the metal of oxygen a key component in the electrolysis process. Things like metal ready, Oxysolv etc ... do convert rust to black zinc oxide and are usually used as a last step after grinding the metal clean. Much of the time you can't get all the rust out (some of it you can't see) so the metal preps are used to convert any rust that is there to zinc oxide.

This fix depends on what you are expecting for results. Do you want the repair to be undetectable? If not, sure just clean up the rust with a wirebrush, treat with a metal prep and paint on some Por-15.

A proper repair would be quite involved and I don't know what your goal is. If you want to to do it right I'd suggest you do some research into basic autobody refinishing as all the answers are there. Quickly: you'd grind the rust off, treat with metal prep, shoot epoxy or a direct to metal primer and then a topcoat typically with a urethane.

Kenr-