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Q & A: de-ionized water and window cleaning

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Most recent answer: 01/08/2014
There is a big push in the Window Cleaning Field to use D.I. water for cleaning windows.I have been at this window cleaning for 50+ years and never heard of this until recently.Water fed poles are used with the various resin tanks hooked up between the water source and the water fed pole.Claimsare made that D.I. water can be use at below freezing temperatures and it does not freeze as quickly as tap water.True or False?Windows can be cleaned with this product with no spotting after drying.Simply wash the window with the D.I.water and it will dry clear.True or False?You can make say 5 gallons of D.I. water put it in a bucket and use it to wash indoor windows or store front windows with the same results.Once you applied the water and re-immersed your brush into the bucket to do the next window wuoldn’t your solution in the bucket be contaminated? This sounds too good to be true.
- Peter V. Cuprak (age 65)
I'll try to answer some of that.

I can't think of any good reason why de-ionized water would not freeze. Its freezing point is actually slightly higher than that of tap water. It might supercool a little more before freezing, but once a little contamination got in, that possible advantage would be lost. As you say, it'll get contaminated pretty quickly by the brush. It might make more sense to add a little alcohol if you just want to inhibit freezing.

The one real advantage would be that the thin film of salts that you get from dried tap water wouldn't be there. If the DI water is simply being sprayed on the windows and left to dry, that could make a difference, especially in areas with 'hard' water. In more conventional uses, it doesn't seem like it would matter much.

Mike W.

Lee H

(published on 10/22/2007)

Follow-Up #1: window spots from de-ionized water

My very conscientious window man used the deionization for the first time on a very hot day. Little spots remain on most of my windows. I do not know what to do. Technically if the spots remain, they are ruined... The exposure of our home is dependent on clean windows
- Linda Tell (age 65)

Thanks, that's important information for other users. We don't know what's in those spots. If it's some leftover salts (from imperfect deionization) maybe wiping with just enough DI water to remove them will help a lot. Distilled water would be even better. If it's some sort of film of organic matter (not necessarily ionic) maybe a wipe with some rubbing alcohol would be the best bet.

Good luck! (and let us and other readers know how it comes out)

Mike W.

(published on 01/08/2014)

Follow-up on this answer.