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Name: David
Status: other
Age: 50s
Location: N/A
Country: N/A
Date: 1999-2001


Question:
While driving in the winter in Kentucky, an auto gets it underside covered with salt and other snow melting corrosive solutions. Question, after washing under the auto what can be sprayed on the bottom of the auto to neutralize these solutions? No matter how well the car is washed corrosive solutions are traped in the cracks and crevices? Will any of the following mixed with water do the job: borax, vinigar, baking soda? What would you recommend for the best rust prevention. We get tons of salt and calicum scattered on our roads each winter.


Replies:
David,

You have raised an issue as nettlesome as death and taxes -- all inescapable. Simply put, there is no practical way to prevent salt from encouraging your car to rust out. Your idea to was the underside of the car as best you can is a good idea even if you can't rinse out all the nooks and crannies. Also beware that some caw washes use recycled water. Imagine the damage that can do when your well-intentioned efforts actually make things worse. If you use a car wash, ask the operator if they use recycled water.

None of the things you list will neutralize the salt or its effects. In fact, all of them would be almost as bad as salt. Actually, salt (both sodium and calcium chloride) simply makes the water better able to conduct an electric current. On order for iron to oxidize and form iron oxide (rust), it must surrender electrons to oxygen. Dry iron in the presence of oxygen oxidizes very slowly. However, if salty water is present, electrons can flow through the solution from the iron to the oxygen and rusting can really take off.

Unlike salt water, a non-ionic de-icer -- like the ethylene glycol antifreeze in your radiator -- would not encourage rusting because the glycol is a non-conductor. However, economic constraints and other factors make such a de-icer impractical for use on roads.

I have always wondered why auto manufacturers don't use sacrificial (magnesium) anodes like those attached to the steel hulls of some ships. Magnesium oxidizes more easily than iron. When the two metals are in electrical contact, any oxidation that occurs happens on the magnesium rather than on the steel.

I have a satellite dish that is bolted to a concrete pier. I have successfully prevented the metalwork from rusting by electrically connecting the structure to a buried piece of magnesium salvaged from an automobile engine. The system has been in place for four years and there is no trace of rust on it anywhere.

I hope you find at least some of my response to be helpful.

Regards,
ProfHoff



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