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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, ( 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 ( on the suspension / undercarriage (See also Road salt)
• 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