Fighting Rust FAQ

From Dave's SwedishBricks mail list and the MG Experience Forums.
As far as I know, British and Swedish cars rust in approximately thesame manner. Contents:

• POR-15 Storage and Usage Note.
• My rust treatment program
• The corrosion process and various protection schemes
• Is there an easy way of removing the undercoating?
• How can I deal with surface rust?

POR-15 Storage and Usage Notes

As of yet I have not tried 'POR-15 rust preventative paint', as I have been pleased with Eastwood's rust-preventative products; however, recently I have become disappointed with Eastwood's long-term durability........ I would like to try POR-15, but first I have a couple of questions for the people that have been using it for awhile:

1. I know the POR-15 spiel says it can be top-coated with a paint of your choice, but is this really the case? Eastwood's 'Rust Encapsulator' also claims to be capable of being used as a primer-coat, but in my experience it creates a very soft finish; which can easily be chipped off with a fingernail! Is their anything special you have to do to promote adhesion (Some kind of POR-15 approved primer?)???

2. How much surface rust does it 'need' to adhere to the surface and actually stop MORE rust from forming? Eastwood's 'Rust Converter' requires a light layer of surface rust to be truly effective..... Otherwise it just bubbles again in the 'clean' areas.

3. Can I apply rubberized undercoating directly to POR-15? I would like to touch up some spots underneath my chassis where the undercoat has flaked off, but first I need to seal the surface-rust; and my experience with Eastwood's rust-proofing products leads me to doubt that they would be suitable for this task.

4. Can I paint POR-15 on top of primer? Say I have a panel which has an area where the paint has flaked off, exposing bare (Rusting) metal, and primer; can I pain the entire area, OR JUST the bare metal with POR-15?

5. Is POR-15 Self-Leveling, or does it need to be sprayed on to provide a satisfactorily smooth finish?

6. Do you have any hints or tips for using POR-15 to ensure the results promised by the company?

7. If properly top-coated, are the positive effects of POR-15 indefinite; or does it eventually lose it's ability to prevent rust from forming?

I apologize if the list grew to be a bit lengthy, but I fear it could not be avoided...... Any help answering these questions will be greatly appreciated!!!!!! I am also interested in your experience with other POR-15 products, including their "Floor-Armor Concrete Coating" and "PELUCID Clear-Coat"; though they are not the current priority....... Thank you in advance for any light you can shed on this matter, as your advice has the possibility of saving me from a rather nasty rust-induced migraine sad smiley ......

Yours Truly, Sam

1. POR sells an intermediate coat to be used as a base for top-coating with standard paints. POR rock hard and extremely resistant against chipping or scratching. It is still flexible however, so it can be used on springs. In my experience it will not "scrape off" unless mixed improperly with thinner.

2. It doesn't need any rust at all, but a very light amount of surface rust is reported to help with adhesion. Their "Metal Ready" product will cause this flash rust after use.

3. I don't know the answer, but I suspect roughing up the POR15 or applying their primer would give a suitable surface for undercoating to stick to.

4. Yes, but you defeat the main purpose of using POR15 - it's ability to bond to the metal and stop rust from spreading. Painting on top of another coating will render the POR15 only as effective as that base coat.

5. It has excellent self-leveling properties. I've applied with a cheap, course brush and had a glass-smooth finish form. I've even brushed away drips that were half dry, and it still leveled itself to the point that I couldn't see where I brushed it.

6. Their instructions are accurate an honest. Follow them to the letter. The most important thing is that there are ZERO contaminants on the metal to be painted. I would even suggest using clean gloves to handle the cleaned parts before painting, to prevent sweat from getting on the surface. POR15 is not forgiving at all. It will either last forever or come off in sheets. Prep is everything.

7. Properly applied it's pretty much permanent. POR15 will eventually "gray" if exposed to sunlight for long periods of time, but the rust-preventing properties will be undamaged. If the parts will see direct sunlight, you will want to give them a top coat with UV protection. POR sells these also, in different finishes. I've have good results with these top coats. They aren't as tough as the POR15 itself but are as durable as any other paint I've used. They are also easy to touch up should the top coat become damaged.

I have no experience with the other POR products in your list, but I've heard good things about the clear one and plan to try it someday.

Hope this helps! - Steve

1 - POR15 has it's own product, called Tie Coat (I believe, just look on the web site), that you use over the POR15 and then you can paint over it with whatever you want. I used the Tie Coat over POR15 in the wheel wells of my 356, then painted over it with standard auto paint and it has held up perfectly for years.

2 - POR15 works best on freshly cleaned rusted metal, with as much of the rust removed as possible. This is because it required a tooth to the metal for proper adhesion. If the metal is smooth, or was never rusted to begin with, you need to add that tooth. You can use a disk sander to scuff the surface or just use the company's Metal Ready product (again, on their web site), which is an acid to etch the surface. I've done it both ways on my 356's underside and again it has held up perfectly over the years.

3 - For the rubberized undercoating you need to use the Tie Coat first over the POR15.

4 - You can only use it on bare metal, not over primer. It just won't work. The primer will eventually fail under the POR15 and it will peel.

5 - POR15 is self leveling and is best applied in two thin coats with a brush. But it can be sprayed if you thin it. If spraying, use a gun that you can throw away after you're done...it's just easier.

6 - Just follow the directions EXACTELY and the coated surface will outlast you, your kids and your grandkids. Of course the metal will rust through from the uncoated side before that...

7 - See #6

The biggest disadvantage of POR15 is actually proof of just how good it does it's job... It's almost impossible to remove once correctly applied. So much so that many body shops will turn down working on car that has been treated with it, and the ones that will work on it will charge a premium just because of the difficulty in removing it...makes it really hard to weld in a new panel.

- Emil

IPD offers a rust treatment paint called POR-15. Its suppose to chemically bond to surface rust and be a permenant fix. I've used it on several of my cars with great success. Just don't get it on your skin. You can't wash it off with any common solvents. You have to let it wear off which can be kind of funny when its accidently splattered on your face.

Anyway, one negative aspect of this POR-15 paint is that it tends to bond to the lid of the can to the can itself. The label warns you about this problem and suggests placing some plastic wrap between the lid and the can. This keeps the lid from bonding but also doesn't make for a truly air-tight seal of the can. I've wasted two cans already by having the contents dry out over the course of a winter. With the second can, in addition to the plastic wrap, I placed the whole can in a freezer bag and then placed about 50 pounds of weight on the lid hoping to compress the lid to the can to form the air-tight seal. This didn't help.

At ~$15/pint, I can't keep wasting paint like this. Has anybody found a good method to store this stuff?

Pete

Just read some articles on your "Fighting Rust FAQ" link. I note that someone was complaining about the POR-15 emulsion drying out. A couple of things to try that may prevent this are:

1. Turn the can upside down when storing, if any minor leak to the atmosphere is present it is quickly sealed as the emulsion is slowly exposed to air thus forming the perfect gasket. (An old painters trick)

or

2. Before you seal the tin, place a gasket of kling film (saran wrap) directly on top of the emulsion, this acts like a skin on custard. Then seal the tin as directed with a further cling film gasket in the lid to stop binding.

Hope this helps!

Cheers, Kim

Go to a (auto) paint store and buy some new, small volume (1/2 pt.) paint cans. Or, use other comparable small air-tight containers. Carefully (no dribbles on the lid/container interface) split up the POR-15 into smaller quantities so you will have little or none leftover after each use. I believe it is impossible to successfully store a partially-full container of the stuff for long periods.

MM

I bought POR-15 at a car show last weekend and they sold it in a six-pack. It was sort of pricey i.e. $30 for six 4 oz bottles. But this should eliminate the need to throw an entire pint away. Note: The salesman stated that the paint has a 6 month shelf life after being opened.

Brian W

I have won some battles. I used an angle grinder and POR-15 as well as the POR-15 rust reducer. I used the angle grinder to get what I could then the rust converter then POR-15 followed by primer followed by aerosol touch up paint. I have some back this spring after 2 years and some is still unsullied.

I found that zinciifed rust is stiff and brittle so if you plan to pound it into a shape suitable for Bondo or something then do all the grinding, shining, and shaping before you use the rust converter.

You must seal it as well as you possibly can. That means both sides of the metal which is hard on rocker panels, corners of doors etc but easy on bullets in the centre of door panels.

I also suspect my rust was not half as bad as I thought it was. I am going that route again this spring with the other rear fender area, the other doors, the other rocker panel,... And if it isn't november by then I will go back and fix the stuff from two years ago, worst to best. It would be really nice to follow all this up with a good was to help seal the body up a bit.

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My rust treatment program

Well it's spring time in the north east and time to repair the ravages of winter...

In a message earlier today about POR-15, Andre' says:

> does it work well to prevent the
> rust from coming back. I did some body work last summer.
> To
> my great displeasure, the rust returned with in 2
> months.
> Does the paint from IPD offer me any
> good chance of helping, or am I doing something
> fundamentally wrong with the prep-work.

Thanks Andre' you've expressed my frustrations well. Especially the part about the anti-rust primer having salt in it. I've had the same results and I thought I was doing things right too.

Last summer I used Corroless, a rust inhibiting and encapsulating primer sold by Eastwood. It was supposed to be impregnable. I did the work (on my 17yr old 244) completely and thoroughly using electric drill mounted wire brushes and "Oxysolve" (another chemical which is supposed to change the rust into a zink phosphate coating). This I followed up with regular auto primer and finish paint.

This spring the rust is back. In most of the same places. I'm sure I have slowed down the deterioration process but I'm winning no battles. I'd like to hear from others who have won some. Anyone...?

John R

> Does the paint from IPD offer me any
> good chance of helping, or am I doing something
> fundamentally wrong with the prep-work.

Here's the rust treatment method I use ever spring with a high success. Note that I don't say 100% success because there's always a small spot either missed or improperly treated. But through itterations of treatment year after year, I've managed to keep the rust under control. The trick is not to let the rust get too far advanced.

1) Grind the loose surface rust off using a power drill with a circular wire brush disc as the attachment. This won't take the rust off down to the metal but gets the bulk of it off. I make sure that I grind atleast an 1/2" of good metal and paint around the infected area. I've seen rust spread underneath the paint without a hint of anything wrong to the naked eye.

2) Wipe down the work area with a dry rag to try to get the remaining debris like paint dust away from the work area. At this point, the infected area likely will still have a thin layer of rust on it.

3) Paint the area with POR-15. I've tried other types of rust treatment paints but this is the best. A somewhat close 2nd is a paint called 'Extend' which you can find at local auto parts places or even K-mart. It's much cheaper and is neat because it changes color from a milky white to black as it bonds with the rust. But I think POR-15 is better. I've tried other non-chemically bonding paints like Rustoleum's rust treatments with almost zero success.

4) The next day, paint over the POR-15 with the proper color touch paint from Volvo.

5) Repeat 1-4 every sprint and/or fall. You'll never win but if you do it regularly you'll keep the rust under control.

Other notes on rust:

Climb around underneath your car and check for places where rocks have pierced the undercoating material. Once that undercoating seal is broken, water and salt gets up in there a rots the floor real fast. I peal the loose undercoating stuff off, treat as described above, and then coat again with fresh undercoat spray. Also, the jacking points tend to develop surface rust because the paint gets chipped off while lifting the car.

Pull the lower trim off every so often. On both my 240's, rust has started behind the lower trim. I'm not sure why since this area is protected from stones. Maybe water and salt gets trapped between the trim and the car and eats at the paint?

Someone else wrote:

> "Oxysolve" (another chemical which is supposed to change the rust into a zink
> phosphate coating). This I followed up with regular auto primer and finish

I bought this 'Oxysolve' from IPD a couple years ago. IPD advertised 'Oxysolve' and 'POR-15' as a pair giving the impression that you should first treat the rust with the Oxysolve and then paint with the POR-15. When I received the two products, the POR-15's label explicitly says NOT to treat the rust infected area with any type of pre-treatment (like Oxysolve). I followed the POR-15 instructions and have never used by Oxysolve on anything.

The corrosion process and various protection schemes.

"RUSTEVADER" - with a name like that I think this product would be forcibly repulsed by some of the previous cars I've owned (Karmann Ghia & Fiat 850). I can just imagine it flying out of my hand if I got too close!

Anyway I normally don't nit-pick, but when I do I tend to go on a rampage; so I guess I'll further defend my scathing opinion of the "RUSTEVADER" While I don't claim to be the ultimate expert in this area, and have not in fact reviewed the patents as have others , I do have some knowledge of the corrosion process and various protection schemes. Of course I crumble quickly under group pressure and will shut up if I'm wrong or just plain too annoying. Also, I have great respect for John & Darryl having taken the time to investigate this product - the technology is in fact valid, but the application is not.

A steel surface without any protection corrodes because adjacent surface sites can become either anode or cathode. In the presence of water electrons flow from the anode site to the cathode site through the metal. Water tends to become partially dissociated into H+ and OH-, at the anode positive Fe ions combine with OH- to eventually become Fe2(OH)6 which is the same as Fe2O3+3H2O. The electrons which go to the cathode allow the H+ to form with dissolved gaseous oxygen to become H2O. The electrochemical driving force for this reaction is due to the difference in the activities of the dissolved oxygen and the Fe, H & OH ions at the two types of surface sites. (BTW, when I lived in Boston "iron ions" was pronounced "ion ions"). The reason some sites choose to become anode and some cathode may initially be due to a variety of reasons; eventually, however, these sites may become locked in due to their geometric configuration. The more difficult diffusion of species in and out of "pits" can cause local concentration fluctuations in the solution which effectively set up the electrochemical "cell". The pits, as you can imagine, are the anode sites where rusting occurs. This is also similar to the enhanced corrosion at crevices, such as the rocker panel seam just above the lower trim strips behind the doors on 242's. It is difficult for the dissolved oxygen to diffuse to these sites, so they become anodes -wherever the oxygen can be accessed more easily will tend to become cathode.

Cathodic protection works by attaching the steel to something else which serves as the anode so that the entire steel surface becomes a cathode and therefore doesn't rust. An example of passive cathodic protection is the plating of steel with a less noble metal such as zinc or dangling a zinc block in your radiator. In these cases the zinc is in electrical (physical) contact with the steel *and* both are in contact with the solution. The primary driving force which makes the zinc an anode is the difference in activity between the Zn and Fe ions (I think this is the work function for you physics types). The zinc, therefore, is the sacrificial electrode, it wants to corrode at the steel's expense.

Active cathodic protection works by using an external bias to make the steel surface a cathode and something else the anode. In this case even a material more noble than iron can be made the cathode (such as graphite). This technique is used with great success in protecting ships, bridges, oil pipelines, etc.; these are all things which are immersed wholly in the corrosive solution (apparently moist soil works well for pipelines). Also the "sacrificial anode" is immersed in the solution and is connected electrically (through the battery) to the steel surface. Note that something like a graphite anode will tend to corrode very slowly (much slower than steel would otherwise corrode) and still serve to protect the steel.

The original "RUST EVADER" used this method, although I'm not sure of the anode material. The reason this device was/is such a piece of crap is that it is a misapplied technology. A car is (hopefully) never immersed fully in the aqueous solution, there will always be wet spots on the car that don't contact the anode. These wet spots will corrode in the old fashioned way of setting up alternate anodic & cathodic surface sites, the solution doesn't "see" the more active sites of the sacrificial electrode. The "new" rust evader I don't understand, but if it's trying to treat the whole car as a capacitor plate then the opposite plate of the capacitor can be treated as the "anode". Simply applying some kind of charge to the car's body shouldn't affect the way corrosion proceeds on an isolated spot, it will still set up localized anodic & cathodic sites - there might be some shift in the absolute activities of the ions, but there will still be localized *differences* in these activities. I kind of think about it this way - the extra electrons may reduce the ability to form positive Fe ions and hence reduce the anodic reaction, so you would expect corrosion to reduce, but the extra electrons will also tend to promote the cathodic reaction which must occur to counter the anodic reaction, therefore corrosion should increase. I think the "RUST EVADER" company is trying to change its patents/technology /marketing in such a way as to make you think they've improved what they must have realized was a dysfunctional product. Remember, just because something is patented doesn't make it any good (like the new coke). OK end of diatribe. Actually I would love to be wrong because my car needs something like this - Let me know if you have convincing evidence to support its use.

BTW, JC Whitney does sell something like this which claims to "flood the car with electrons" every eight seconds by electrical discharge, and it does use anodes (which I refer to as sacrificial). It also retails for quite a bit more than the engine overhaul pellets - this stuff totally rebuilds your engine for only $9, awesome!

Regards, Bob

Is there an easy way of removing the undercoating?

Kyle writes:

> Hi, Is there an easy way of removing the undercoating? I've be chipping it off but it's going really slow.

Yes, there is an easier way. Take your brick to a HD Truck repair facility. Many have HP Steam systems used to degrease million mile rigs before re-builds. A few brushes of the old wand and the rustproofing will melt right off. A low enough temperature setting does not melt the rubber though since no trucker wishes to replace *all* hoses and electricals come re-build time.

Paul G

How can I deal with surface rust?

From Appiazgato on 1.8.96:

> I am renovating (not "restoring") a P-1800 and I need some advice on dealing
> surface rust and preparing the heavily pitted surface for painting. The car
> spent five years outside exposed to northeastern US weather and is about 25%
> covered by surface rust.

> Common restoration wisdom suggests dipping or sandblasting to remove rust.
> Neither of these approaches is practicable for my circumstances.

> I've spot-blasted. This cleans the surface beautifully and gets deeply into
> rust pits. I've also used a body
> grinder with 24, 50 and 80 grit. Grinding does not get into the pits and I
> don't like the idea of removing too much metal. It also is
> energy-consumptive. Wire brushing also doesn't get into the pits.

> I have also used acid ("God! It's God, I see God!"). Naval jelly doesn't
> touch my rust. Daredevil that I am, I experimentally treated my hood
> (bonnet, for you Brits) with muriatic acid (dilute hydrochloric acid). I
> brushed it on to wire-brushed rust and after about an hour, the rust
> disappeared!

> My local auto paint suppliers say to wipe the rust-blushed surface with SEM's
> Rust Mort, a phosphoric acid-based "rust killer," let it set up, and then
> prime. So I did.

> Over sand blasted, ground or muriatic acid (plus Rust Mort) treated areas
> I've sprayed DuPont Variprime, a two-part self-etching enamel primer.
> Phosphoric acid is the etching/rust attacking ingredient in this primer.

> Ok, so how am I doing? What works? Do I wire brush, apply Rust Mort and
> prime? Do I apply muriatic acid, Rust Mort and prime? Do I bite the bullet
> and spot-blast the whole car one inch at a time? Do I forget Rust Mort
> entirely? Does the self-etching primer have enough rust killing power to
> kill and seal in rust for the duration? And what about POR-15? Has anyone
> really gotten several year's worth of experience with it as a basis for
> finish paint work? Do I just resign myself to stripping and repainting in
> five years?

Your post raised a few quetions in my mind and I'll through out a few other comments for consideration and some of my experiences.

I'm curious why sandbasting isn't an option for you. If you have the spray and ventilation capacity to properly do the other things you have experimented with, why not prep and bring in a blaster for a day or two. If you're shooting Variprime I assume you have your own compressor. There are some inexpensive attachments that will allow you to use that and blast with a bucket of sand (good for large scale spot blasting) if you're not familiar. (I've never used them but the concept seems useful. Can anyone comment?) Or perhaps even subcontract out the sandblasting or at least parts of it. If the rust is as extesive as you say, the fee may be well worth it considering the amount of time, effort and materials expense needed in order to get by with the other methods. I feel that surface prep is easily the most essential part of the refinish, a few extra hours or dollars here are probably well worth it in the long run.

You also mention grinding as "energy-consumptive". Do you mean energy used as in electric power, or maual labor. If you are running an air tool, I don't see it as more consumptive than most. What about a combination of grinding and then spot blasting the remaining bad areas? I can appreciate your concern about removing too much metal, but I feel it is far worse to have the rust come back a short time later. Because then, not only will you have wasted much of your work if you have to refinish, but you will again be removing metal -likely more then if the job was done properly the first time.

I'm wondering if the metal removal might be a mental block (it's tough to grind away what appears to be perfectly good metal ) or if the amount of remaining metal is scarce. If that is the case, I would consider any safety issues. Do you have enough good metal to insure durability? You may be better off cutting out the severly rusted areas and patching in some new sheet. (You could even use fiberglass and poly-resin, although I'd don't know how I'd trust it for large diameter patching) How important the underside appearance of the patch is will determine the amount of work involved.

A possible complication to serious acid etching, and I stress possible because I have no real word data relating to auto refinish, is acids have a tendancy to make some metal brittle. If you are faced with thin, brittle metal in some spots....

Some of the metal etch prep products I have used do seem to neutralize small amounts of rust, but they only act on the surface of the rust -creating a hard black finish like anodized alum. However, If you scrape or chip the neutralized section away, the rust is still there and will act up again. Often, I use a Dremel moto-tool to pinpoint grind these spots before conditioning the metal for priming.

Though I've not tried POR 15 (I will if it is contrary to past experience), I've tried other rust preventive auto and marine primers and have come to the same conclusions about all of them. They can be useful in areas where proper surface prep is difficult (either because you cant reach with tools, or because parents refuse to allow a cutting torch on their property) but there are some drawbacks that may not make them them the best choice for paintable surfaces (depends on your circumstance mainly). First, most do not guarantee rust protection if you reduce them to put through a spray gun. So then your faced with a less then ideal primer finish that is not sandable (in order to preserve rust blocking ability). I have also not found any that handle lacquer based primer-surfacers well. Plus, I've had less then spectacular success with their protective effects over a 4-5 year period. Hit or miss in some areas. Curing conditions seem very important though.

One last possibility that I would like some feedback on is the use of molten lead as rust neutralizing body fill. I don't know of many shops that still use it today (my mom thinks the fumes will kill me if I try it, any tinners or bullet casters care to comment ) I'm thinking that the heat of the molten lead would drive out any moisture and oxygen in the repair area, effectively sealing and stablizing the rust. Does it work that way?

Comments and clarifications welcome.

Ron

Our 1971 Chev Impala was hit when it was only one year old, and repairs were done with lead, around the right tail light assembly. The car had 4 body jobs since then, and the ledded area never needed any attention. However, working with lead takes a lot of practice, little cold and it crystalizes, little hot and it drips. As far as vapours, there are appropriate masks with filter mediums, that should be used for any time of body work. Most auto body product of today are very toxic.

Jim K