INHIBITING RUSTING OF A CAR BODY

Zinc works for Electrolysis on steel boat hulls in water. Cars are more of a rust problem--I have spent thousands of hours painting boats which have both.

Electrolysis is local contact between two dissimilar metals.

My advice is to remove all the rust and then coat the steel--The case of: An ounce of prevention is worth a pound of cure. Once the original coating fails and the steel starts to rust and you coat over it, it will scale and continue to erode. A coat of zinc paint will slow the process, but will eventually be consumed and then start back on the steel. The zinc is as you stated, sacrificial, whether a paint or zinc bar.

Your real problem is rust and the only real cure is prevention from a coating, not cathodic protection. I have researched this here and got some good information-along with years of doing maintenance on a well kept vessel.--We had hundreds of zincs, but only where the steel was submerged or flooded in sea water.

Sandblast the rust and coat it or let it go-Rust never sleeps Regards, K T

Buy a Corvette, newer ones have aluminum Frames, supporting the Fiberglass bodies, then all You have to worry about is damage from Sunlight to the Gel-Coating.

I'm not sure that this will work in your application. Typically the sacrificial metal (in this instance zinc) is isolated from the base metal and contact occurs through the galvanic activity that occurs during submersion in salt water. (A result of the oxidization process). Possibly some form of aftermarket galvanization (there are several aerosol products available) could prolong the agony some but such coatings will need to be applied prior to painting.

Have you considered marine coatings? The upper parts of ships are made of steel, exposed to direct salt air and harsh environments and do not benefit from sacrificial plates. These exposed surfaces must be protected by their coating alone.

Being from the U.S. I'm not familiar with GB plates. Could you explain?

I have several suggestions.

One is a car cover of a water repellent synthetic fabric. We've used one on my wife's 99 Lexus, that sits outside all the time. (http://www.calcarcover.com/)(their "WT" grade fabric) The car still has the wax the dealer put on it when we took delivery. This suggests that in your environment such a cover may do well at keeping the salt away from the body seams.

Another possibility is the periodic application of a light mineral oil like automatic transmission fluid to the external body seams or perhaps the entire exterior. There could be an issue with compatibility of the oil with plastics and rubbers in the car body. Perhaps a vegetable oil (olive oil?) that is good for that. I would ask around the island about whether the old timers like that approach.

Check out a product called Salt-X. Google it for info and sources. Check ebay. I've found at least one ebay seller of fishing gear that ships internationally and sells Salt-X. I've had no experience with it yet but a lot of friends who regularly visit one of the the salt covered desert areas of the western USA swear by the stuff.

Ed Weldon

I'd put my money on polysiloxane

bwire ---

I googled polysiloxane and it seems that its big application is as a concrete sealer. I got the impression that it cures or hardens. Is that what you're thinking of? Do you have any experience with the us of this stuff on things like steel car bodies? Any good links that tell that kind of story?

Ed Weldon

Did you follow the hyper-link? Did you google Acrylic Polysiloxane?

A Patented (US 6, 281, 321 and

EP 0 941290) Polysiloxane finish coat

• Provides unrivaled short, medium and

long-term color and gloss retention

• Offers the same high performance

anti-corrosive protection when used

in an approved two coat system as

that achieved with traditional three

coat systems

• Good abrasion and impact resistance

helps reduce damage during service

• Long term flexibility makes Interfine 979

ideal for use on thin gauge steel

fabrications.

I've lived on a few islands where salt spray corrosion was always taking shine out the waxing on the cars. I don't recall the product name that is used in the inner auto body cavities which has wetting properties. Often it seemed the body panels rusted from the inside out without it.

There was a liquid product called "Blast-Off" we used to remove and stop the oxidation before painting too.

My thanks to everyone who have so far replied.

Alan.

Great and informative.

Thanks,

Alan

I did, in my travels, run into different products we used that may be of interest--

Ospho™--Phosphoric acid--works on rust and bleed, but any scale left and it's only temporary and you still have to remove the root cause of the rust.

Aluma Brite™--Another acid that is designed for Aluminum, but works good for cleaning the rust bleed that discolors the marine paint.

Corroseal™--Not sure what it is exactly, but we found it at the end of my fishing career and I didn't get to see if it would stand the test of time--It did a combination of things--we could scale the rust and paint this stuff on. It turned any rust purple and then formed a plastic coating which we could paint over.

I had to paint a 110' boat, stem to stern, every year(two part, three coat system). It was only worth doing, if you do it right. Once you get behind on the rust, it took several years to get it back under control.

I repainted an old Dodge van years ago. I used Ospho, combined with a rust prep coating that was sold and recommended by Dupont for use on reused bare metal areas. I covered it with epoxy primer, followed by Imron paint. There was no paint on any of the roof when I got ti. The paint showed no signs of the rust after 8 years of Florida sun. When I sold it it was as good as when I painted it. Lots of words, but I believe Ospho works well.

Another product out there is called Extend. It is designed to convert rust into a weatherproof coating. Eastwood sells another product called Por-15 that seems to be popular with people restoring older cars. I have had very good results using a product called Corrosion X. It is in an aerosol can , and dries to a wax like substance. I have used it inside some rust prone areas around the shop.

If I tow around an old Ford, will it serve as a sacrificial anode to stop my Chevy from rusting?

Thank you. Very kind.

Fiberglass might not make good frame rails, but a similar (stronger) product such as "Carbon Fiber" is gaining popularity, and with it lower costs. I believe Lotus makes a two-seater Carbon Fiber car now that isn't available in North America, probably because of the rigidity of it in normal crash tests.

But if You want to bring up older American cars, the frames/body panels were overbuilt that is why they last longer, and weigh so much, nobody gave much thought to lightening the weight until they went racing, or were looking to save at the pump. Some racers even dipped whole bodies in acid bathes to thin the metal panels to paper thin sheets, to the point where driving the car in a headwind would make the panels ripple, and make noise.

When Japan started making Cars they concentrated on making the cars as lightweight, and cheap as possible to flood the market with cars that got twice the fuel economy as an American/European counterpart. Thus You wind up with a car made from very thin stamped steel, which if rust starts is very hard to overcome.

Now China is getting into the fray, but their biggest problem seems to be in quality control of the alloys they produce, some products may be suffering from Lead being in the Steel the way it seems to break so easily.

______________________________________________________________

The future seems to be in hyroformed aluminum, or fiber/resin frames, and a whole myriad of choices in composite panels.

If it was only about weight, I would say, "sure, bring it on". I would need a lot of convincing to believe that the few ounces saved by using carbon fiber would actually save much fuel. I DO believe that a ligher vehicle will stop quicker...a very important consideration when racing, and for safety on the street. However, auto body design has so much more to it than aesthetics. Some of the reality shows on TV have a lot to answer for because they tend to ignore simple engineering considerations. A lot of cars are "unibody", like an aircraft. The body is actually the chassis, or frame if you prefer. At least in whole or in part. Most of these "considerations" have been addressed, and resolved, more or less in modern steel automotive design.

Price....painted steel is pretty cheap, especially compared to stainless.

ease of manufacture....steel can be stamped. It can be formed really quickly, without long cure times that resin based equipment with minimal worker (and possible error) input.

Less labour in manufature.

Steel fenders and body work are designed to crumple under impact, providing a cushion which absorbs energy. There are many different directions that the impact can come...like rollovers, and sideswipes. Most of these requirments are government mandated, and all the engineering work has been done. A new material, even fiberglass (which is not all that new) will have to go through a lot of testing to meet the ever changing regulations.

The steel rails are designed to hold the heavy engine in place, away from the passenger compartment. When they give way, they are designed to direct the hurtling engine away from the cabin. This involves bending in predetermined ways. Fiberglass or carbon fiber don't really DO the "bending" thing...

Carbon fiber is lighter for the stiffness you get. In an accident involving an aircraft (which was riddled with carbon fiber), we in the air force were told to beware of the toxic nature of the material, and masks were only the first level of defense. Wrecks with carbon fiber panels broken all over the place were hazardous because the way the stuff broke it was a nasty pile of needles lying in wait for any rescuer. The dust which blows up , don't get it in your eyes....

Steel is more easily repaired in a minor fender bender. Fiberglass simply fails, and carbon stands up really well until even it gets destroyed, but by then it is catastrophic.

Steel can be shifted and dragged back into place in manufacture or repair, and a crumpled fender will still function as a fender. Crumpled fiberglass doesn't shrug off a few dents like steel will. I dragged my fender away from the tire once, and drove that car for a long time...it sort of "oil canned" back into place. No cost repair. Gotta love that.

Steel can be welded to repair a hole. Of course, fiberglass can be filled as well. If the hole is in a stress panel, the weld will stand up pretty easily. Fiberglass can be repaired in much the same way.

Cars made from steel can be crushed, and remelted into new cars. Fiberglass just fills up landfills.

Surprisingto some, fiberglass is heavier than steel for most robust applications...carbon fiber is light, but in either case, it is not the weight of the fibers, but rather the weight of the resin. Because carbon is so much more expensive, it tends to be made with a little more care, a little more engineering has gone into it. Read...expense... This expense is not minor consideration either! No body makes carbon fiber "chop", for instance. (or maybe they do...but the question would then be, "why?) Gel coat and chop are the way to go, assuming you want to go that route.

When I was rear ended a couple of decades ago, my rear tail light was broken. The fiberglass fenders and hood of the car that hit me exploded into tiny bits. Admittedly, the temperature was well below freezing. Fiberglass reacts differently when the temperature fluctuates wildly. That makes it use in stress panels difficult to engineer. The guy that hit me was faced with a huge repair bill. My tail light globe needed to be crazy glued back together.

Resin panels support combustion.

Fiberglass panels don't rust. However, the bolts and screws used to hold on everything from door harware to window trim DO rust.

Well, these are some engineering considerations. I didn't realize whien I started this list how biased it was away from fiberglass. But to understand why fiberglass is not used as much as it probably should be..well, this is a start.

Interstingly enough, I was talking with a fella a few years ago who was traveling in Africa. He noticed that there is a lot of sisal which some of their best and brightest were using to weave into very coarse cloth, or mat. Then they would soak this mat in resin and mould it into body panels, barrels, and a thousand other things. It wasn't super light, but it WAS super cheap, very resistant to fungus, moisture, and damp. I wonder what ever happened to this project.

Suggest you get a car that utilizes 2 side galvanized sheet in its manufacture, or one with a fiberglass body.

I have seen advertisements of a system that you clean off an area of about four square inches of the frame down to bare metal and attach a sticky pad which is connected to some sort of black box that you plug in that reverses a small current and prevents corrosion of anything electrically connected to the frame. I have seen this on a television show here in the U.S. called Two Guys Garage but can't seem to navigate to any information about that product. It is marketed to car collectors and I have seen it in use a few years ago.

Complete Scam, every conductive piece of Your Car's frame/body (if Metal), is electrically/physically connected to the Negative Post of the Battery. Which cycles Hundreds of Amps of current per hour.

Do You think any device You connect to the Metal Frame/Body will Have any effect on that charge. Especially if it's power source is the Car's Battery...

If it is powered by a Large outside source, like the A/C Source in Your wall outlet You could only use it while the Car is parked in Your Garage, and it still won't do squat!

what you describe is a sort of cathodic protection of a car body. This is not possible 'cause cathodic protection works only if you havea a metal placed inside an electrolyte, like a boat in water or a pipe in soil .Cathodic protection will not work in the air.

Also what you use is not a cathode but an anode that protect the metal (the cathode).

S

corrosion protection

http://www.zero-rust.com

ZeroRust Performance:
Continued refinement of the Zero Rust formula has netted ASTM-B117 salt spray testing results exceeding 2000 hours at 3.5 mils dry film thickness (d.f.t.). This equates to 600 hours per dry mil, which was previously unheard of in an air-dry system. The Zero-Rust rust protection performance exceeds that of commonly used red oxide, DTM Acrylics, water-borne alkyds and epoxies on these types of surfaces. Zero-Rust rust protection performance has been confirmed by industrial, commercial and marine industry. Black and Red Oxide Zero-Rust are recommended as the primers for corrosive services -- including marine, coastal and industrial surfaces. The effectiveness of Zero-Rust on bare steel surfaces is optimized at 2.5 to 3.0 mils d.f.t. over profile. Rule of thumb: Zero-Rust should provide five years of rust protection for every a mil d.f.t. With the addition of a topcoat or a thicker film of Zero-Rust to take the ultraviolet rays, sealing protection can easily double.

This Bag is 3 mils thick:

But if it gets cut, Your Balls are gonna get Wet!

Or you come to the States and buy a Delorean!

Try googling " electronic rust control " and read the info. there.

They are selling a lot them here in Canada.

Prices are about $ 200.00 Canadian and they are very easy to install .

The Navies of the world have been using this type of rust control for years and it involves simply introducing a very small constant trickle charge to the metal body of the vehicle ( or ship ) to stop the rusting process.

If it works for them, then i submit that it is probably worth the $ 200.00 bucks to try it out. The system is also easy to transfer from one vehicle to another so you only have to purchase it once.

Wouldn't dragging a ground strap essentially produce similar results?

See Strider6's Post regarding cathodic protection above.

In Navy (& other) Vessels, the salt-water is an electrolyte, And the Boats do not use the Hull as a Ground conductor for the electronic circuits.