Distilled water alert

Wouldn't pure acid be a solid/powder? HCL is aqueous, not a liquid.

Alex and PE,
Basic chemistry tells you that distillation will distill anything which vapourises at or below the temp used. Therefore basic chemistry tells you that distillation will not purify water 100% if there is anything in it which does vaporise at or below the being used. What the PH scale is, is irrelevant in understanding that. You have said in your own answer that distillation won't drive everything out of water. So it would seem you are contradicting yourself.

So once again, why do assume that distillation will make 100% pure water which you then test by looking at its PH?

The results everyone are quoting show its not PH7 but still you persist in the assumption that it should be. Sounds very much like a very basic misunderstanding of chemistry to me.

Ian Grant said:

Does that mean it's produced by one of those methods rather tan by all

Ian

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Ian, all of those processes are involved in producing the final product.

Kvistgaard said:

hi Photo Engineer - would you happen to have a URL to that thread? I'd like to read it, because I have been using the water from our tumble dryer, which works by condensing the water from the wet clothes. I'd assume that whatever problems water from a basement de-humidifier has, water from my tumble dryer has as well.

I've been using the water from the dryer to wash my negatives after development, not for mixing chemicals.

Thanks.

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There's lots of fungus spores in the air, lots of bacteria in wet clothes (wet clothes are extremely disgusting...drying really cleans them). Just a lot of nasty crap, which is why you're not supposed to drink dehumidifier water.

FWIW, I've been printing some negatives that were processed 50-60 years ago with water that came straight from the well on our farm. No treatment whatsover. The source for the well was the Olagalla Aquifer in western Kansas. There's been no practical deterioration of the film whatsoever. That doesn't by any means suggest that all well water in the world is suitable for photographic processing. That's a matter of the local geology.

Here's the link...

Deja vu all over again.

(there was a url link here which no longer exists)

In my biased opinion, DW - real or RO - is so cheap in America I don't know why anyone wouldn't pay $1/gal for it for mixing developers and Photo-flo. Just cautionary, especially in areas of hard water.

Using condensates is probably worse than using typical tap water. Whether A/C, dehumidifier, or the dryer type Autumn speaks of (never heard of such a thing) the air is loaded with dust and pollen. The resulting water is anything but pure.

Alex Hawley said:

FWIW, I've been printing some negatives that were processed 50-60 years ago with water that came straight from the well on our farm. No treatment whatsover. The source for the well was the Olagalla Aquifer in western Kansas. There's been no practical deterioration of the film whatsoever. That doesn't by any means suggest that all well water in the world is suitable for photographic processing. That's a matter of the local geology.

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Good enough for corn, good enough for Dektol, I always say......

Ian Grant said:

Does that mean it's produced by one of those methods rather tan by all

Ian

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It's Wal-Mart. They saved cost by eliminating the ampersand.

Grammar don't come cheap there bubba...

Isn't this all irrelevant, except to say that distilled water is an even better stop bath than we all gave it credit for?

By my thinking, all that matters with distilled water is that it is essentially free of particulate contamination: no chlorine, no fluorine, no lead, etc.

All you need are some pH strips, sodium- or potassium hydroxide, hydrochloric or sulfuric acid, something with which to measure pH, and a table with optimal developer and fixer pH's, and you should be able to use water with any reasonable pH and adjust it to the correct pH after mixing.

Am I not right? Granted a lot of people, myself included, don't nitpick this much and assume that the pH of the water we use is "close enough" to the optimal pH for mixing chemistry.

Paul Verizzo said:

Recently? At one of the major water distributors?

Why would it be so cheap?

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It is often a waste product - alcohol distillation, steam heating, dehumidification, cooling towers, salt production ...

As noted, just because it is distilled doesn't mean the pH is 7. Vinegar can end up in the 'distilled water' if the feedstock includes soured grape juice. Or it can have quite a bit of alcohol in it if the juice is still in the fizzy stage.

The term 'distilled water' has come to mean water that is good-enough-pure for most uses. Technically 'distilled water' could contain only the merest drop of water.

FilmIs4Ever said:

Isn't this all irrelevant, except to say that distilled water is an even better stop bath than we all gave it credit for?

By my thinking, all that matters with distilled water is that it is essentially free of particulate contamination: no chlorine, no fluorine, no lead, etc.

All you need are some pH strips, sodium- or potassium hydroxide, hydrochloric or sulfuric acid, something with which to measure pH, and a table with optimal developer and fixer pH's, and you should be able to use water with any reasonable pH and adjust it to the correct pH after mixing.

Am I not right? Granted a lot of people, myself included, don't nitpick this much and assume that the pH of the water we use is "close enough" to the optimal pH for mixing chemistry.

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correct, but you have to ask why the thread was started and to my mind it was because there is a basic misunderstanding of what distillation of water achieves.

I think that people who use distilled water for the final wash are mainly concerned about drying marks from minerals dissolved in the water--mostly calcium I suppose--and that's also what people who use distilled water in their irons are worried about. Could it be that water destined mainly for irons might be a little acidic to help keep the iron clean, and we're just not told that?

It reminds me of a story of a friend who used the venerable technique of putting boiled linseed oil on a saw blade to keep it from rusting and found that it rusted faster that way. He called the manufacturer and spoke with their chief paint chemist, and learned that it contained dryers that made the oil dry faster and incidentally caused metal to oxidize, but there were no warnings to that effect, since that wasn't the main intended purpose of the product.

FilmIs4Ever said:

Isn't this all irrelevant, except to say that distilled water is an even better stop bath than we all gave it credit for?

By my thinking, all that matters with distilled water is that it is essentially free of particulate contamination: no chlorine, no fluorine, no lead, etc.

All you need are some pH strips, sodium- or potassium hydroxide, hydrochloric or sulfuric acid, something with which to measure pH, and a table with optimal developer and fixer pH's, and you should be able to use water with any reasonable pH and adjust it to the correct pH after mixing.

Am I not right? Granted a lot of people, myself included, don't nitpick this much and assume that the pH of the water we use is "close enough" to the optimal pH for mixing chemistry.

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I'd have to agree, these are the same reasons I ended up using cheap distilled water instead of tap water. It's just more predictable in terms of dissolved solids.

And without any buffering from carbonates, etc. the pH doesn't mean much, as another person pointed out, since the chemistry added to the water is going to more than dominate the hydrogen ion concentration, or lack thereof. Whether the water is 'pure' is kinda immaterial in this context, isn't it?

Didn't someone mention dissolved CO2 is responsible for the acidic pH of 'distilled' water by formation of carbonic acid? I wonder if boiling it out and bottling it warm in glass jugs makes the slightest difference in actual use, other than by saving time in the batch operation. Or I could get a life. If only they had 'em on sale, too, at Wal-Mart.

Probably the most important warning is don't put distilled water in your Whisky.

When I used to run an analytical lab we bought and used distilled water only for certain tests, the rest of the time we used de-ionised. Prior to that I always used de-ionised water when I worked as an emulsion/photo chemist, only using distilled for parts of emulsions manufacture. But whether de-ionised or distilled the pH was always 7.

I once asked a very experienced motor mechanic what difference it made using distilled water compared to tap water in a car battery, his reply was with one you battery will last a year with the other only 12 months.

There are extremely few occasions as photographers where we really good distilled water, tap water is usually OK for the rest, and yes boiling is usually sufficient to remove a lot of the potentially harmful substances.

Ian

David A. Goldfarb said:

It reminds me of a story of a friend who used the venerable technique of putting boiled linseed oil on a saw blade to keep it from rusting and found that it rusted faster that way. He called the manufacturer and spoke with their chief paint chemist, and learned that it contained dryers that made the oil dry faster and incidentally caused metal to oxidize, but there were no warnings to that effect, since that wasn't the main intended purpose of the product.

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So, just to re-state the original problem, just as "boiled linseed oil" ain't "boiled linseed oil" anymore, "distilled water" ain't "distilled water" anymore. Makes one think about whiskey, doesn't it?

Photo Engineer said:

Dissolved CO2 would not lower the pH of DW very much, probably to about 6.5 or so.

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PE - I have to completely diasgree with you. 18 megohm water, DI by ASTM Type II specification, will be pH 5-5.5 in a mere 30 minutes when exposed to air with stirring. As more carbon dioxide dissolves in, it will trend to pH 4.5.

I have seen this happen countless times while testing pH and alkalinity in the labs I've worked at.

In fact, the conductivity changes so fast - away from 18 megohm that you need to use a flow-through cell to accurately measure the conductivity from DI water as it comes out of the tap. If you put it in a beaker, and put an electrode in it, it most likely will fail the 18 megohm requirement for conductivity.

If your DI is pH 5, it will be perfectly acceptable.

Ian Grant said:

There are extremely few occasions as photographers where we really good distilled water, tap water is usually OK for the rest, and yes boiling is usually sufficient to remove a lot of the potentially harmful substances.

Ian

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The one place where I do use distilled water is for the silver nitrate solution that I use for albumen printing, but now this thread has me thinking...

Well, I never stated that it was a problem, just a possible problem due to pH. Distilled water is assumed to be pure water with some dissolved gases from air including CO2. Our atmosphere is acidic and oxidizing and so the assumption is that the water would be in equillibrium with the air at about pH 6.5 FWIW.

Water with ammonia in it, when distilled carries over ammonia, and water with HCl in it carries over HCl. Pure HCl is a gas, and pure Sulfuric Acid is a liquid (unless one considers Sulfur Trioxide to be the parent compound in which case it is a solid).

So, DW is not necessarily DW and is not necessarily pure. It may also be more acidic than chemists assume it to be, and the buffer capacity may vary at any given pH value.

I viewed several DW units at Kodak and at major suppliers of photo chemicals. They all basically distill the water and do not use RO for purification unless the water is also labeled DI or deionized. Kodak performed both the distillation and deionization and supplied DW and DW, DI water in the plant.

So, my precautionary note was intended to alert you to the fact that your DW could be good or could have some contaminants in it. For now, we can assume that it is pure but slightly acidic in the normal case, and can vary up to pH 7.0 (best case but not assuring purity). It also means that alkaline DW is not really pure.

City and well water can vary from about 5 - 9 depending on municipality, location and additives used such as fluoride and descaling agents.

So, this was intended to be some things to think about in case you have problems, it was not intended to be a major conflagration.

PE

Kirk;

This from Wikipedia:
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"Acidity of carbonic acid
Carbonic acid is diprotic, that is it has two hydrogens which dissociate from the parent molecule, and thus there are two dissociation constants:

H2CO3 ⇌ HCO3− + H+
Ka1 = 2.5×10−4; pKa1 = 3.60 at 25 °C, for -log (2.5×10−4) = 3.60.
HCO3− ⇌ CO32− + H+
Ka2 = 5.61×10−11; pKa2 = 10.25 at 25 °C.
Care must be taken when quoting and using the first dissociation constant of carbonic acid. The value given above is correct for the H2CO3 molecule, and shows that it is a stronger acid than acetic acid or formic acid: this might be expected from the influence of the electronegative oxygen substituent. However, in aqueous solution carbonic acid only exists in equilibrium with carbon dioxide, and the concentration of H2CO3 there is much lower than the CO2 concentration, reducing the measured acidity. The equation may be rewritten as follows (c.f. sulfurous acid):

CO2 + H2O ⇌ HCO3− + H+
Ka = 4.30×10−7; pKa = 6.36.
This figure is quoted as the dissociation constant of carbonic acid, although this is ambiguous: it might better be referred to as the acidity constant of carbon dioxide, as it is particularly useful for calculating the pH of CO2 solutions.


[edit] pH and composition of a carbonic acid solution
At a given temperature, the composition of a pure carbonic acid solution (or of a pure CO2 solution) is completely determined by the partial pressure of carbon dioxide above the solution. To calculate this composition, account must be taken of the above equilibria between the three different carbonate forms (H2CO3, HCO3− and CO32−) as well as of the hydration equilibrium between dissolved CO2 and H2CO3 with constant (see above) and of the following equilibrium between the dissolved CO2 and the gaseous CO2 above the solution:

CO2(gas) ↔ CO2(dissolved) with where kH=29.76 atm/(mol/L) at 25°C (Henry constant)
The corresponding equilibrium equations together with the relation and the neutrality condition result in six equations for the six unknowns [CO2], [H2CO3], [H+], [OH−], [HCO3−] and [CO32−], showing that the composition of the solution is fully determined by . The equation obtained for [H+] is a cubic whose numerical solution yields the following values for the pH and the different species concentrations:

TABLE OMITTED
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The operative points are in the table. The pKa of carbonic acid is 6.35 and that would follow from what I have posted. It varies with the partial pressure of CO2, the absolute temperature. The values I used came from STP values from my old chemistry courses. So, maybe global warming and the increase in CO2 concentration has something to do with it.

Old values that I have placed it at about 6.5 in distilled water. However, I have to believe your values Kirk which only emphasizes the fact that the pH can vary with conditions, and pH is not a measure of purity by any means.

PE

rob champagne said:

correct, but you have to ask why the thread was started and to my mind it was because there is a basic misunderstanding of what distillation of water achieves.

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Well, since this is in the B&W film paper and chemistry forum, anything other than a discussion of the chemisty of distilled water as it relates to traditional B&W silver based photo finishing is outside of the scope of this site

In seriousness, the method of distillation of water AS IT RELATES TO PHOTOGRAPHY (why else would it be in this forum) is irrelevant as long as the particulate content is basically eliminated, as pH is adjustable with the addition of acids and bases after the processing solution has been mixed.

I think that Rob has a good point. People assume that distilled water achieves a neutral pH with high purity, but it may not in all cases and that was exactly my point.

PE

FilmIs4Ever said:

...the method of distillation of water...

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DW: Condensed H2O vapor? Condensed water vapor?
At any temperature and pressure of distillation other
volatile chemistry will carry into the distillate.

I don't see where scale becomes a factor other than
very long term. The condenser portion of a DW
installation is subject to only H2O vapors
and some minute amounts of other
volatile chemistry. Dan

rob champagne said:

And what makes you think that distilling makes water pure. I ask because it seems that a lot of people think that is does. It does NOT. Distilling is a process for separating fluids with different boiling points. Anything that boils [edit]below[/edit] the temp you are using will get distilled off. That could be several fluids including chlorine which will get distilled with water.
And distlling does not deionise water and water that has not been deionised will never be PH7. So to put it in a nutshell, I don't understand why the question has been raised in surprise that distilling does not make water a more neutral PH than it does.

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I agree, but people think distilled water is pure water. Those who homebrew photo chemistry should test for ph...EC

Photo Engineer said:

So, this was intended to be some things to think about in case you have problems, it was not intended to be a major conflagration.

PE

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For heaven's sake, don't pour any more DI water on it, it might conflagurate!

I am not going to argue about water anymore after this:

Distilled water is *pure enough*. Most companies even list the acceptable impurities on the outside of the bottle you buy it in. If CO2 is a problem, then just mix chemistry in a vacuum