Cooking water before mixing with developer?

game · Sep 7, 2005

Has anyone heard of cooking water before mixing with developer?
In that way oxygenlevels should get lower and with that the oxydation of chemicals. This off course results in a mixure that does not get old as quick as it would get normally...

A guy in the shop told me this today....

clogz · Sep 7, 2005

It is a good idea. For long lasting developers - the 2 bath variety like Diafine - distilled water is recommended.

Cheers
Hans

game · Sep 7, 2005

why is that?
Does distilled water holds lower oxygen levels as well?

Game

Donald Miller · Sep 7, 2005

game said:
why is that?
Does distilled water holds lower oxygen levels as well?

Game

Distilled water does have the potential of containing free oxygen. The inclusion would occur after the distillation. The absolute best, if one is so inclined,( I am not) would be to heat distilled water.

Ryuji · Sep 7, 2005

It is generally best to heat water in a vacuum chamber if the chemical is sensitive to dissolved oxygen. Most photographic chemicals are reasonably ok with average level of DO because of high salt contents, especially sulfites.

When I mix developers for testing their chemical properties, or for long term storage, I use water line that does not go through an aerator, but instead goes through double filtration. Then I heat the water in vacuum, and then cool to the mixing temp (say 50C) while it's still in vacuum. After mixing the chemicals, I bring the solution back in vacuum again and let it cool to room temp. BUT-this level of operation is seldom, if not never, necessary for usual darkroom work.

Even if you use distilled or deionized water, if you let the water in contact with air for prolonged period of time, the water will absorb gas from air, including oxygen and carbon dioxide.

df cardwell · Sep 7, 2005

In other words, mix only the amount of solution you'll use in a relatively short period,
and use distilled water.

gnashings · Sep 7, 2005

Darn... and I just bought a new vacuum chamber

srs5694 · Sep 7, 2005

game said:
why is that?
Does distilled water holds lower oxygen levels as well?

The main reason to use distilled water is to minimize contaminants. Tap water can contain various metals, organic compounds, etc. Assuming your local water department is doing its job and your plumbing is in good condition, none of this should be harmful when consumed, but it's a big question mark when mixing photochemicals. Commercial developers are generally formulated with additives that neutralize or otherwise counteract common tap water contaminants, but they can't cover every possibility. Home-brew formulas are less likely to include such additives.

That said, most people seem to do just fine using tap water. If you're not getting the results you expect, though (either immediately or in terms of shelf life), using distilled water is worth trying.

titrisol · Sep 7, 2005

It is a good practice for long lasting developers, when distilled water is not available.
Not only you'll keep some of the oxygen out (which will more likely be dissolved back) but you'll get rid of any volatile gases (such as chlorine), bicarbonates/carbonates, and some salts will become insoluble and decant.

Kirk Keyes · Sep 7, 2005

Donald Miller said:
Distilled water does have the potential of containing free oxygen. The inclusion would occur after the distillation. The absolute best, if one is so inclined,( I am not) would be to heat distilled water.

Unless you are distilling under a vacuum or an inert gas, your distilled water will be saturated with dissolved oxygen as the water will be in intimate contact with the surrounding air. That means you would be wasting your time trying to get rid of oxygen by distillation.

Absolute best would be to boil under a vacuum and cool under a vacuum - distilled, deionized or not. Does not make a difference which you start out with.

Water at room temp will only contain about 10 mg/L oxygen. (Unless you have supersaturated it my shaking it in a partly filled conatiner or or run it through an aerator.) That is not very much oxygen. Unless you are doing the kinds of things that Ryuji mentions, you are not going to be getting any benefit from boiling your water if it is oxygen that concerns you.

If you still feel the need to boil your water, at least tranfer it to an air-tight container while the water is still petty hot, so that is will not reabsorb much oxygen while you are waiting for it to cool enough to use.

game · Sep 7, 2005

outofoptions said:
Yeah, you see it bubble, but you can bubble it until there is no water left. Also, raising the temp may make the water more reactive to the air and you may get more of it diffused in than you started with. Where do you think all of those bubbles come from?

Monueculs move faster at higher temperatures, right?
I don't believe cooked water ends up having more oxygen after cooking than before. I do feel that indeed water will eventually absorb the oxygen that has been cooked out...
As for now I plan to treat things a little more loose and don't be spastic about destilled or cooked water. I'll just use my normal water.
At least, reading all the posts, I don't feel a enormous concensus about either cooked or distilled water in comparison to normal water. Besides: distilled will cost more and I'm poor.

Are there guys that are completely agianst the use of normal water in their darkrooms?

Game

srs5694 · Sep 7, 2005

game said:
Are there guys that are completely agianst the use of normal water in their darkrooms?

Yes there are. I don't happen to be one of them, but I've seen posts from people who advise 100% use of distilled water for mixing darkroom chemicals. Their arguments have been presented in this thread in weaker form -- tap water has unknown quantities of unknown contaminants, and that leads to unknown effects on the chemistry. As I said, though, I'm not a "100% distilled water" sort of guy, so I won't try to advocate this position.

srs5694 · Sep 7, 2005

outofoptions said:
Just because you see the water bubble does NOT mean you are driving the oxygen out. If that is what was happening, at some point there would be no more bubbles? Right? ;-)

Perhaps this is just folklore, but I seem to recall hearing that the small bubbles you see forming along the sides of a pot of water before it begins to boil are air. Once the boiling begins, though, the bubbles consist of steam.

Also, a tip from cooking that I'd expect applies to photo chemistry, too: Draw cold water from your water tap and heat it to whatever temperature is required to mix the formula; do not use hot water from the tap. The reason is that hot water more readily leaches metals from your pipes, so it's better to start with cold water and heat it. In reading up on XTOL, I ran across the advice to heat water in a non-metal (presumably glass) container to avoid metal leaching from the container. Take all of this with a grain of salt, though; it could all just be urban legends for all I know.

Aggie · Sep 7, 2005

srs5694 said:
Perhaps this is just folklore, but I seem to recall hearing that the small bubbles you see forming along the sides of a pot of water before it begins to boil are air. Once the boiling begins, though, the bubbles consist of steam.

Also, a tip from cooking that I'd expect applies to photo chemistry, too: Draw cold water from your water tap and heat it to whatever temperature is required to mix the formula; do not use hot water from the tap. The reason is that hot water more readily leaches metals from your pipes, so it's better to start with cold water and heat it. In reading up on XTOL, I ran across the advice to heat water in a non-metal (presumably glass) container to avoid metal leaching from the container. Take all of this with a grain of salt, though; it could all just be urban legends for all I know.

The cold water you draw from the faucet has been sitting in those pipes picking up much more of the metal leachings than the hot water would.

Ole · Sep 7, 2005

Aggie said:
The cold water you draw from the faucet has been sitting in those pipes picking up much more of the metal leachings than the hot water would.

But the hot water has been sitting just as long in the cold pipes, and even longer in the water heater. Besides the solubility and solubility rate is much higher in hot water. So there will still be far more metals in hot water!

clogz · Sep 7, 2005

This is getting too complicated for me...Contemplating going digital....now we are going to need all the water we can get, be it distilled, demineralized to put out all the flames..

Cheers
Hans

Ryuji · Sep 8, 2005

game said:
At least, reading all the posts, I don't feel a enormous concensus about either cooked or distilled water in comparison to normal water.

Watch out. Internet forums are full of craps and consensus may not be correct scientifically. At least in darkroom chemistry, I see a lot of errorneous posts that are left uncorrected. (Also watch out for popular darkroom chemistry books and popular magazines.)

I generally don't believe that you need a special water to mix regular developers, stop, fix, toner, etc. (You do need a very pure water to make good emulsions, but that's a different story.) If you get decent municipal tap water, that's fine for darkroom use.

Ryuji · Sep 8, 2005

outofoptions said:
Also, raising the temp may make the water more reactive to the air and you may get more of it diffused in than you started with.

Solubility of gas in water generally decreases with increasing temperature. Check with a decent freshman chemistry textbook.

Ray Rogers · Sep 8, 2005

Thats right.

And as any brewer will tell you, cabonation is best done COLD.

(This is for CO2 but the same would be true for O2 as well.)

Ray

titrisol · Sep 8, 2005

NOP, when water boils the bubbling is gaseous water (steam) raising from the bottom of the pot which is the hottest spot.
You cannot have more oxygen than what you started with, solubility of oxygen is dependent on temperature, as you cool the water the oxygen goes in from the air again.
When you see initial bubbling (before boiling) is a lot of things leaving the water, not only air but chlorine and other gases that most likely will not come back and can help.

I;m not against using tap water in the darkroom, BUT it depends a lot in the quality of your water. If the water has Iron or other minerals in it you may cnsider boiling/fuiltering or a Brita pitcher.

outofoptions said:
Which is exactly why you end up with MORE oxygen than you started with. You don't get to choose which way this reaction works. Just because you see the water bubble does NOT mean you are driving the oxygen out. If that is what was happening, at some point there would be no more bubbles? Right? ;-)

dancqu · Sep 9, 2005

outofoptions said:
Different components boil off at different temps.
So, you may be condensing the oxygen that is
already in the water. Can't find a good answer
on that one.

So one might be left with a concentrate of oxygen
at the bottom of the container depending upon what
other components are present? Dan

game · Sep 9, 2005

Think there is no need for pseudo scientific discussion
It's simply true that if one bolies water, oxygen levels will drop. Maybe not much, but it'll happen.
Fact two is that low levels of oxygen in water increase durabillity of develloper with which you mix it.

BUT for all the reasons and speculation that has been going on in this topic there is reason to assume that all this work in lengthing the life of your chemicals is not worh the effort.

So, although in theorie it all seems really nice. In practise one can generally forget about it (and just remember it in case you have problems with your printing).

Gerald Koch · Sep 9, 2005

Ryuji said:
If you get decent municipal tap water.

"Aye, that's the rub", to quote WS.

Jerry

Cooking water before mixing with developer?

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