Future rust prevention, I need some help. What about POR15?

Shuie · 10-25-2003, 07:07 PM

I’m in the process of completely refurbing my '73. The car is disassembled to a tub state. The rotted front pan has been drilled and cut out, and the battery boxes have been cut off and replaced with flat sheet metal.

The battery box panels have been have been fit and welded in place. Surface prep was done with a grinder and denatured alcohol. I used 20ga galvanized sheet metal for the patch panels, and welded them with a Lincoln 100 HD converted to MIG with C02/argon mix for shielding gas. After the welding was done I sprayed the seam with a cold galvanizing compound, ground it flat, and used an aerosol primer on it. I am starting to notice an orange (rust) color around the welds already and I’m a little confused and frustrated. Have I done something wrong on the battery boxes, or is this normal? I want to make sure I’ve got this process down to a routine exercise before I strike an arc anywhere near the front pan.

Another area of concern is the surface rust that I have removed from one of the one of the rear kidney bowls and the front platform above the gas tank under the master cylinder reservoir. The kidney bowl is obvious contamination from the surrounding backseat area (leaky window seal that I caught before the longitudinal wheelhouse was eaten up), but I’m not sure what happened up front. It looks like brake fluid has overflowed, eaten away paint, and surface rust has resulted over time. I used my angle grinder with a wire wheel to clean it up real good and followed with a coat of the aerosol primer. Rust is showing through the primer after a week.

I want to make sure that rust never eats up the front of this car again. I live in a very humid climate and I have limited time (1 solid day a week) to tool on this car. I’m worried about controlling the rust as I expose unprotected metal while my work progresses.

I need to change something about the way I’m trying to control the rust situation in my car as I’m working on it. It seems like its trying to rust out from under me. I really need about 80hrs straight to work on the car, but that’s not going to happen as long as I’m among the employed. What can I do to more efficiently control the re-appearing rust as I’m working on this car on the weekends?

If I shoot the front clip with some POR15 can I stop worrying about this and work on the car as I have time? Is this stuff that good? I was planning on shooting at least one coat of POR after all of the metal work was done up front anyway, will a base coat help me avoid the problems I’m having? Will the POR stop the surface rust from coming back in the areas like under the master cylinder reservoir?

tshih · tshih's Garage

Yup,
raw primer is porous and doesn't stop rust from forming. You should use POR15 or Wurth Rust Guard liberally over the welds and bare sheet metal as base coats. These products are a reducing protective formulation which seals out water and air (without which rust cannot form).

1974carrera · 1974carrera's Garage

Anytime I have bare metal exposed the first thing I coat with is a self-etching primer. I like to use a CR (chromate) wash two-part self-etching primer made by Sikkens...it will protect bare metal from rusting. I'm sure other paint manufacturers also have a self-etching primer. I then top the primer with Wurth Rust Guard.

john70t · 10-26-2003, 07:15 AM

In some climates there'll be flash rust in a couple of hours. I kept having it pop up after using store bought metal prep(as per instructions) but didn't have any with POR15s "Metalready".

The single chemical cans are useless. Use the 2-stages polymer types and a primer made for raw metal so it has the self etching to get rid of incidental rust and that will actually stick to the metal. The zinc coating should be protecting the raw metal as a sacrificial layer, so rust coming back is odd.

BTW, I hope POR15 works because I've done the interior, trunk and entire underside(especially wheel wells) with it and so far am impressed with the tough shell. It dosn't fix rust itself, and doesn't stick well to loose or greasy paint or smooth surfaces.

RoninLB · 10-26-2003, 08:10 AM

I use Por-15 products.
Two thin coats are better than one thick coat. It has to be primed with their liquid. Sometimes I'll prime with white vinegar.......Ron

k9handler · 10-26-2003, 08:54 AM

POR-15 products are great, use them and be happy!

gsxrken · gsxrken's Garage

"The" body and paint website is Autobodystore.com. They have message board similar to this one where the pros really compare notes. The owner, like Wayne here, also runs a supply store and is very helpful on the phone and on the board. For whatever reason, the board is generally dismissive of POR 15 and leans towards a product called Picklex 20. I used on my Mach 1 restoration, which I conpletely Da'd to bare metal and spritzed with this stuff... it then sat for 7 months (!) in my garage like that waiting for the bodyman to get to it. No surface rust, and the bodyman now swears by it too. The other product I would pitch is 3M weld-thru coating. SPray both pieces right where you are going to weld. Welds are super-prone to rust as it's really pure steel.

cmelecci · 10-27-2003, 05:49 AM

I came across a paint called "Hammerite" and used it on the rusted lower sections of my 82 bronco to buy me spme time untill I can fix it. Well the paint held up for 4 years without any new signs of rust. Since then I've used it brackets and swim platform on my boat and again no rust. I now using it on the floor pans of my project. Not saying it's the only solution, but worth a look.
http://www.hammerite-automotive.com/
Carl

targa80 · targa80's Garage

I am in the same boat as you are Shuie. My tub is down to the bare metal and I am in the process of cleaning off all the little bits of paint body shultz and primer that was left after the inital paint stripping. I also have some flash surface rust to deal with. I will be using the Por-15 but first I will wash the entire tub with a marine clean dry it and the metal etch Metal ready. Metal ready and marine clean are Por-15 products. The metal ready is a Phosporus(spelling?) acid That converts rust and lays a protective coating. I will shoot two coats of Por-15. 45 minutes after the second coat I can spray a light layer of the primer I am going to use. The tech's at Por -15 said this will allow the primer and Por-15 to chemically bond together. Then I can prime as much as I want before painting. They do not recommend using Por-15 over anthing except bare metal treated with metal ready etching solution. You can certainly do sections of the car if you want to. I thought about it but decided to wait until the whole tub is ready.

Shuie · 10-27-2003, 08:57 AM

Thanks guys!

I just ordered some Marine Clean, Metal Ready, and some POR15 from the POR store.

Im doing everything in sections, because everytime I think about this car as a whole I want to sell it and move on. Its less overwhelming in sections

OkieRon · 10-27-2003, 10:09 AM

Hey Guys,

I have a 72T that does not have huge rust issues. There are some holes in the battery boxes and some surface rust in areas around the battery boxes and seam running crossway in front of the gas tank hole. I have not gotten the front down to bare metal. However, I have scraped away at places that had signs of rust. I plan on using por-15 on those areas.
Can you use Por 15 over the top of the coating over metal (like the underbody coating) that came from the factory. What other places are there that are absolute rust worries that could use a coat of POR-15 I might miss.

john70t · 10-27-2003, 10:31 AM

I applied it over the undercoat after washing it well and giving it a sanding with 80 grit and it seemed to stick. Also chiseled off all loose undercoat that was peeling. The scary thing was the floorpan looked good except a fine crack revealed advanced surface rust.

targa80 · targa80's Garage

From what I have read putting Por-15 over anything other than the bare etched metal is a waist of money. They state to remove the possibility of rust reoccurring the Por -15 must bond directly to the metal.

RoninLB · 10-27-2003, 11:13 AM

Quote:

Originally posted by targa80
From what I have read putting Por-15 over anything other than the bare etched metal is a waist of money.

Not in my case. I had some left-over Por-15 clear rust preventive that I wanted to use because of the limited time before the rest of the can cures.

So I cleaned up the outer fender wells of the front wheels with tolune, then acetone, then scratched it with sandpaper. Then applied the clear in 40degF temps. It stood a week before the roads..
That was 40k miles ago. It remains un-chipped and a simple water hose cleans it 90% worth. The A-frame with Por-15 black has some chips.
So I guess the stock fender well flex-undercoating aided the non-chipped Por clear......Ron

Randy Webb · 10-27-2003, 12:45 PM

Be sure to remove and/or neutralize all the rust -- I use a chemical convertor product. It's recently been discovered that bacteria are involved in rust formation -- your car really is being eaten up.

"very humid climate" Baton Rude is worse than that! I grew up there and couldn't wait to leave. I feel for sorry for anyone that lives there. Also, hope you are not anywhere near N. BTR as the air pollution will eat your apint near the chemical plants (if they don't explode and kill you first).

I'd advise moving to New Orleans or Lafayette -- better food & culture to ofset the mosquitos, bugs, corrpution, and .....

Shuie · 10-27-2003, 03:01 PM

Quote:

Originally posted by Randy Webb

Also, hope you are not anywhere near N. BTR as the air pollution will eat your apint near the chemical plants (if they don't explode and kill you first).

I'd advise moving to New Orleans or Lafayette -- better food & culture to ofset the mosquitos, bugs, corrpution, and .....

I was out of town last week for some training. Upon returning to my office this morning, I couldn’t help but be remember how bad this place sucks.

Randy, you sound homesick. Here’s what you've been missing:

All of the refineries have been running full production 24/7 and laying off the Chem E's ever since the price of fuel really started to go up. In an effort of efficiency they have cancelled all of their maintenance contracts. Everyone knows that things like catcracking units don’t require a whole lot of maintenance, right?

That whole West Nile Virus scare last year was such an over reaction on the medias part.

As far as the political circus is concerned, I’m really disappointed in things here. I honestly can’t believe that someone from Louisiana didn’t think of recalling a gubernatorial election before this California thing happened.

Thankfully, DEQ has just announced that we will only be allowed to buy reformulated gas starting next year, so the air pollution problem should be cleared up soon

Randy Webb · 10-27-2003, 03:34 PM

Hah - I agree, La. is being upstaged by Florida and Cal. (all southern tier states, tho...). I've been back for 2 weeks every year since I left at age 18 (I'm 51 now) -- still enjoy New Orleans(!!). Sounds like you're a ChemE. Financially, it could be worse, eh. (you could have just gotten your EE degree in 2000). Good luck! And enjoy the food -- even if you have to drive 90 miles south or west...

Shuie · 10-27-2003, 04:47 PM

Quote:

Originally posted by Randy Webb
Sounds like you're a ChemE. Financially, it could be worse, eh. (you could have just gotten your EE degree in 2000)

I actually graduated EE/C in 2000 from LSU. I guess it could still be worse though. My fiance graduated ChemE in '01, has two other technical degrees, and is currently out of work

. The bottom has completely fallen out of the ChemE field here.

The food is damn good though.

dotorg · 10-27-2003, 05:48 PM

Quote:

Originally posted by OkieRon

Can you use Por 15 over the top of the coating over metal (like the underbody coating) that came from the factory. What other places are there that are absolute rust worries that could use a coat of POR-15 I might miss.

You can, but you'll get no benefit out of it, like others have said, its got to be directly on the metal. When I bought my car the better part of two days was spent by myself and two helpers removing all the underbody coating on my car down to absolutely bare metal, etched with Metal Ready and POR15'd.

becky'sdroptop · 10-27-2003, 06:33 PM

POR-15 really needs to go to bare metal for best results. I have been using it since it first came out and have never had any rust return where it was applied properly. It really is designed to be top-coated with a good UV-resistant color coat if it is on surfaces that see direct sunlight.

We have used the chassis black for years with very good results. They have changed the formulation over time so that it is supposedly more UV-tolerant so that may not be an issue anymore.

For really tough topcoats I have been using PM Industries paint for a couple of years now. It seems to be less prone to chipping than POR-15 but will chalk out it not clear-coated.

WORD OF WARNING - POR-15 is a polyisocyanate so very good respirators with NIOSH-approved particulate filters are a necessity when shooting it. It is actually worse than Imron was for killing your lungs (know of at least one excellent painter that is now taking a dirt nap from his exposure over years with no respirator).

Paint has come a long way in being able to handle existing rust and staying adhered to less-than-perfect subsurfaces. POR-15 or PM Industries (I am sure there are others, too) will really help keep the rust gremlin at bay.