Spot Free Water

[lucid696]

NESLAB, cooling systems manufacture, writes in the Instruction and Operation Manual: "Higly distilled/deionized water, above the 3 megohm-cm region, may become aggressive and is not recommended for use with units with wetted parts other than stainless steel. Distiled/deionized water in the 15 megohm-cm region is definitely aggressive and should not be used."

This is not the correct reference for what we are talking about here. The usage of ultrapure water in cooling systems is very different from washing your car with some DI water.



Extremely pure water (much more pure than an OTC DI product will get you) will dissolve a minute amount of what it contacts--but even tiny trace amounts of silica (very hard to remove from water, BTW) inhibit corrosion.



Also, this needs to be a high velocity environment, where the water is continually dissolving and taking away ions--in a static environment, the ions would saturate the droplet, and no further dissolution would occur.



BTW, the same happens with your ordinary droplet of "polluted" water, too.



Standard corrosion occurs when there is a salt/solid in the water, because corrosion is an electrochemical reaction. My best friend (a chemical engineer for steel manufacturer) tells me that steel makers test corrosive resistance of steel samples by placing them within 100 yards of an ocean coast. The salt spray is what corrodes the steel.

 

[Mark Waldron]

I think Beav hit it right on the head when he said that CONTSTANT exposure to DI water can be corrosive but not just rinsing with it.

After using the CR System for a while now, I'm realizing that doing a DI rinse after washing, as opposed to using a regular water rinse followed by a final DI rinse, works best. I'm getting a little spotting because the regular water is drying to quickly, thus leaving spots that the DI water won't get out.

 

[jet_m3]

that's why i'm using it from start to finish :woot:

 

[The Big Kahuna]

How do the brake disks look after being rinsed with DI water? Do you notice any discoloration?

 

[HumSki]

Every major rent a car company and all major car dealerships rinse their car inventory daily with DI water. If there were a problem with DI water corrosion, they wouldn't be using it. I'm talking Hertz, AVIS, National, etc.



Try DI water on your car and you'll probably never look back.

 

[Setec Astronomy]

I don't see how pure water free of any ions would accelerate corrosion? If so, what are defined as exposed metals and is it all of them or some? I don't buy it.

I found this intruging so Googled for some info. Apparently, de-ionised water will leach ions out of metals thus accelerating corrosion. :shrug:

It is precisely the absence of ions in the deionized water that makes it corrosive...it wants to combine with something cuz it's not combined with anything. But as others have said, the brief contact as a rinse shouldn't be harmful. FWIW, the temperature is important, too--hot DI is more corrosive (as in a heated rinse tank).