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      12-12-2009, 04:18 AM   #1
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Road Salt & Vehicle Undercarriage Care

Road Salt

Although salt is inert when subjected to freezing (15 – 20.oF ) it’s considered the lower limit for salt to melt snow/ice but once H2O, even in the form of moist air (i.e. humidity) is added the freezing point is lowered and the saline solution(salt/water) will have an adverse effect on the vehicles paint and undercarriage.

When washing the vehicle ensure that all salt is removed to avoid a saline solution remaining on the paint finish. Using a durable protection (Collinite Insulator Wax) will provide a sacrificial and renewable protection to the vehicles paint finish.

The salts (often mixed with grit / sand for tyre adhesion) commonly used are;
(a) Sodium chloride (NaCl) the most common salt used
(b) Calcium chloride (CaCl2) works at lower temperatures than sodium chloride.
(c) Magnesium chloride (MgCl2) is the name for the chemical compounds and its various hydrates MgCl2 (H2O) x. These salts are typical ionic halides, being highly soluble in water.

Magnesium chloride is very effective even at the lowest temperatures but also contains the most aggressive corrosives (especially on glass surfaces) and a sprayed brine solution, it is used to prevent snow / ice adhesion to the road surface. A number of state highway departments throughout the United States have decreased the use of rock salt and sand on roadways and have increased the use of solutions of magnesium chloride (often called "liquid magnesium chloride") as a de-icer. Magnesium chloride is much less toxic to plant life surrounding highways and airports, and is less corrosive to concrete and steel (and other iron alloys) than sodium chloride.

Anti-icing liquids; according to State authorities the liquid consists of -Magnesium chloride, Calcium chloride and other liquids works like anti-freeze by lowering the freezing temperature of water and preventing ice from forming a strong bond to the road’
Needless to state that all these salts are acidic / corrosive so once you've removed the ice / snow it may be advisable to 'neutralize ' the residue road salt with an alkaline solution, (Canada-POR15.com) especially from the undercarriage and suspension.

Undercarriage Care

After removing dirt, road grime, and etc with a pressure washer (Karcher Model K5.93M) neutralise the effects of the acidic road salt (Canada-POR15.com) on the suspension / undercarriage (See also Road salt)
Methodology
• Thoroughly spray an undiluted citrus cleaner (P2IS Total Auto Wash) and let it soak in; remove by thoroughly rinsing with water. If you have a pressure washer available, fill tank with citrus cleaner and spray undercarriage (do not use excess pressure as water may penetrate crevices and seams where it cannot drain, causing corrosion), let it soak and then remove with plain water
• Spray undercarriage with (Chemical Guys Bare Bones ) one application will leave no residues, noxious fumes or flammable solvents
• Or apply POR-15 Marine Clean™ and then two coats of a rust inhibitor paint (POR-15 ) allow each coat to dry

Alternative products

Wurth High Build Underbody Spray - produces a jet black, textured finish in wheel wells and on lower rocker panels. This spray will hide a multitude of blemishes and make old wheel wells look factory new. Provides permanent yet flexible protection against flying stones, rust, water and road salts

Wurth SKS Stone Guard - matches OEM Factory applied stone protection on vehicles such as BMW, Fiat, Mercedes-Benz, Porsche and Renault. For use on door sills, front and rear body parts, mudguards, under bodies, rocker panels, etc. Wurth SKS Stone Guard is a water based product and offers easy clean-up. Wurth SKS is paintable and can be top coated with solvent based urethane or water-borne top coats (available in Black or Grey)

See also Winter Vehicle Preparation


An extract from one of a series of unbiased “Detailing Technical Papers” © TOGWT ™ Ltd Copyright 2002-2009, all rights reserved
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      12-12-2009, 03:11 PM   #2
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Seriously I could not care less how the undercarriage looks...It is a 40K BMW not a 400K lambo...

anyhow this is good info for the most anal of those 1 owners out there..
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      12-12-2009, 03:14 PM   #3
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Quote:
Originally Posted by AlBel1214 View Post
Seriously I could not care less how the undercarriage looks...It is a 40K BMW not a 400K lambo...

anyhow this is good info for the most anal of those 1 owners out there..
Those people that worry about keeping their car long term need to worry about degredation of the undercarriage.



I feel like I just studied for my chemistry final...nice read.
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      12-12-2009, 03:22 PM   #4
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^^ True.. If I was planning on keeping this over about 4 years I would be more concerned...
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      12-12-2009, 03:48 PM   #5
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how does one keep their undercarriage clean without access to a detail shop materials?
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      12-12-2009, 05:22 PM   #6
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You mean you don't have a lift in your garage like the rest of us? ha
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      12-13-2009, 07:17 AM   #7
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Quote:
Originally Posted by BrokenVert View Post
Those people that worry about keeping their car long term need to worry about degredation of the undercarriage.

I feel like I just studied for my chemistry final...nice read.
Your exam grades will be posted on to you

It is my intent to educate, based on five plus decades of experience; passing on to my readers the dynamics that take place; the cause and effect not just “ How” it works, but also “Why” it works, as well as an explanation of the scientific terminology and chemicals involved with detailing products. I try to write in a way that helps the reader to understand the technical and scientific facts along with any relevant chemical information, but if you’ve read any of my forum posts / threads you'll already understand just what I mean
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      12-13-2009, 10:17 AM   #8
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I think that saying salt is acidic is not correct, and there is no need to "neutralize" it. It is not alkaline either.

Salt obviously does indeed increase rates of corrosion, but not because it is acidic, and more to do with increasing the rate electron transfer and ion transfer in the water. Since the rusting or oxidation process involves ion and electron transfer, salt increases the rate of oxidation.

I just don't want people going into their kitchen and mixing up solutions of baking soda or sodium hydroxide and spraying it on the undercarriage and thinking it will mitigate rusting.

The main ways to minimize corrosion/rust are to:
- keep things dry
- keep oxygen away
- reduce exposure to salts (this won't prevent corrosion, but will slow it down)
- reduce time exposed to water/oxygen/salt (cleaning)

If you can't do these things (clearly you can't with a car undercarriage), then coatings or non-rusting alloys may be the best option.

Cleaning and protecting is obviously important, and I think that was your main point.
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      12-13-2009, 04:29 PM   #9
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You are correct in your assertion that dry salt is neither acidic nor alkaline, as stated its inert, its only when water is added that it becomes a corrosive alkaline (pH 9.0)

As a professional writer I need to ensure it speaks to the level of the readership; without becoming obtuse in scientific explanation or terminology and phrase things that are understandable and have a practical application. Never forgetting there is a fine line between divulging knowledge and insulting the reader’s intelligence.

Last edited by TOGWT; 12-14-2009 at 11:52 AM.
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      12-02-2012, 09:49 AM   #10
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Quote:
Originally Posted by Artmasterx View Post
I think that saying salt is acidic is not correct, and there is no need to "neutralize" it. It is not alkaline either.

Salt obviously does indeed increase rates of corrosion, but not because it is acidic, and more to do with increasing the rate electron transfer and ion transfer in the water. Since the rusting or oxidation process involves ion and electron transfer, salt increases the rate of oxidation.

I just don't want people going into their kitchen and mixing up solutions of baking soda or sodium hydroxide and spraying it on the undercarriage and thinking it will mitigate rusting.

The main ways to minimize corrosion/rust are to:
- keep things dry
- keep oxygen away
- reduce exposure to salts (this won't prevent corrosion, but will slow it down)
- reduce time exposed to water/oxygen/salt (cleaning)

If you can't do these things (clearly you can't with a car undercarriage), then coatings or non-rusting alloys may be the best option.

Cleaning and protecting is obviously important, and I think that was your main point.

I just want to make sure I understand this correctly.


In this part of Canada they use road salt heavily in winter, sometimes it looks green maybe its the other chemicals added to it.

Are you saying that if I go to a spray wash in winter (what I've been doing on average once a week on my VW for the past few years)

This is bad because it will accelerate the corrosion process? I guess I was given poor advice, I thought the goal was to wash off all the salt right away and to not let it sit on the car for long periods. It seems like it may be better to have the salt sit there if its cold enough and rinse it off less often? A lot of the roads here look "wet" even during sub freezing temperatures...

What steps can I take to slow down or prevent as best as possible rust from forming prematurely? I don't have access to a lift or these undercar paints/sprays.
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