[window cleaner]

I don't know if I should ask this sort of question in this forum, but it's worth a try.

I'm a window cleaner and use what's commonly known as a Reach and Wash system for health and safety reasons; no ladders needed.

Anyway, it works like this:  water is purified though a reverse osmosis unit and then de-ionised through a resin chamber.

This treated water is then pumped through a long pole, through a brush head and used to wash windows.

When the windows dry; they're clean; no spots; no runs; just clean because the water is 'pure'; so I'm led to believe.

The manufactures say that 'pure water' is more 'aggressive' than normal tap water because purified and dionised water wants to return to its natrual impure state; so has better cleaning abilities.

Is this just waffle?  It does work though.

Can anyone explain in simple terms that a Geordie window-cleaner can understand how water purified through a reverse-osmosis system and then de-ionised works for cleaning windows?

[Alberto_Kravina]

Maybe deionized water is a better solvend because it has hardly any dissolved salts, so the less dissolved salts there are in the water the more it cleans.

I'm not 100% sure about this, though....

[window cleaner]

Maybe deionized water is a better solvend because it has hardly any dissolved salts, so the less dissolved salts there are in the water the more it cleans.

I'm not 100% sure about this, though....

That sounds about right, but then wouldn't soft water (pure water) have the same effect without the water having to be de ionised also?

Why de ionise it?  The final stage after the reverse osmosis process is for the water to be fed through a chamber filled with mixed-bed resin where 'something' happens to the water's ions.)

I'm not even sure if the water is de ionised; I believe it's more of an exchange of ions.

I hope this makes more sense to you lot than it does to me!

I'll post any results here on the window cleaning forum which I moderate (don't laugh).

[Borek]

That sounds about right, but then wouldn't soft water (pure water) have the same effect without the water having to be de ionised also?

Are you using deionised water for all the cleaning, or only to rinse at the end? Deionised water will not leave any traces as these are usually things that were dissolved and were left on the glass surface when water (solvent) dried out.

Why de ionise it?  The final stage after the reverse osmosis process is for the water to be fed through a chamber filled with mixed-bed resin where 'something' happens to the water's ions.)

I'm not even sure if the water is de ionised; I believe it's more of an exchange of ions.

Sounds like deionisation. Are you regenerating resin with strong acid/base?

I'll post any results here on the window cleaning forum which I moderate (don't laugh).

That's the power of internet - no matter how specialized discussion is, there is 6 billions people on the world and you may always find someone interested

[window cleaner]

Are you using deionised water for all the cleaning, or only to rinse at the end?

We use deionised water for all the cleaning, and for the final rinse.

Deionised water will not leave any traces as these are usually things that were dissolved and were left on the glass surface when water (solvent) dried out.Sounds like deionisation. Are you regenerating resin with strong acid/base?

Although I've heard it's possible to regenerate resin, it's simpler to purchase it.

But I could simplify my question:

Some window cleaners who live in soft water areas don't use a reverse osmosis sytem, as their water is fairly pure anyway, which is the net result of the water after the reverse-osmosis stage.

They just pass their water through a resin-filled deionisation chamber and use the result to clean their windows with.

We test our water purity with a TDS (Total Disolved Solids) meter which measures water purity (within certain limitations) in PPM.

So my first question is, what makes deionised water such a good cleaning solvent?

Secondly, would heated deionised water increase the cleaning efficiency?  

Thanks for your help so far.

Things were much simpler when all that was involved was a bucket and set of ladders!

[Borek]

We use deionised water for all the cleaning, and for the final rinse.

As is, or with some cleaning agent?

Some window cleaners who live in soft water areas don't use a reverse osmosis sytem, as their water is fairly pure anyway, which is the net result of the water after the reverse-osmosis stage.

They just pass their water through a resin-filled deionisation chamber and use the result to clean their windows with.

We test our water purity with a TDS (Total Disolved Solids) meter which measures water purity (within certain limitations) in PPM.

So my first question is, what makes deionised water such a good cleaning solvent?

I can think of two reasons. First was already mentioned - no traces of dissolved salts left when drying. Second is more subtle. Hard water often reacts with soaps/detergents used, deactivating them this way or another.

Secondly, would heated deionised water increase the cleaning efficiency?  

Could be - every kind of grease will be easier to clean as they soften when heated.

Things were much simpler when all that was involved was a bucket and set of ladders!

You don't have to carry ladder with you now, so it was simpler before, today it is lighter

[window cleaner]

As is, or with some cleaning agent?

As is; nothing added; just DI water.

Second is more subtle. Hard water often reacts with soaps/detergents used, deactivating them this way or another.

Can you add to the second statement?  Remember, you're 'talking' to a Geordie window cleaner.

To me it seems that pure water reacts more with soap.  Just a little bit of detergent gives you far more 'bubbles' than hard water.  (If I'm being a bit technical here; just ask me to slow down).

Thanks.

Ken.

[Borek]

As is; nothing added; just DI water.Can you add to the second statement?  Remember, you're 'talking' to a Geordie window cleaner.

Classic example is with standard toilet soap. In the presence of hard water it precipitates some greasy and grey salt - as long as the calcium and magnesium dissolved is not precipitated, such soap is not working as it is consumed in precipitation. Fancy detergents don't precipitate but in reality - even if they don't precipitate - they often somehow react with both cations and their effecitivity is reduced (note: these are my observations, not confirmed by rigorous experiments, I can be wrong here).

To me it seems that pure water reacts more with soap.  Just a little bit of detergent gives you far more 'bubbles' than hard water.  (If I'm being a bit technical here; just ask me to slow down).

That's exactly what I am talking about.

It is possible that there is other effect taking place also - in the presence of charged ions structures built by the detergent particles on the water surface (and on the impurities surface as well) can be distrorted making detergents less effective. Once again, that's only educated guess.