need advice with cloudy mixture

[David Lyga]

When I mix Dektol I get a nice, clear solution (Philadelphia tap water).

But when I mix D-72 I get a milky, cloudy solution after I add the sodium carbonate. Why, and what can be done to rectify this? The D-72 works fine but I store my solutions in clear PET plastic bottles and I hate to see the cloudy solution on my shelf (there really ARE worse things to complain about, true).

Philadelphia tap water is not hard: it makes a nice lather with soap. What does the proprietary formula (Dektol) have to prevent this? - David Lyga

 

[David Lyga]

No Dektol is said (by Kodak) to actually have somewhat INCREASED capacity. There is a slight difference. But what MAKES the cloudiness? That is what I want to nail. There are people who have a foundation in chemistry that would be able to respond fully. Thank you Michael R.

I just did a Google search and, indeed, Philadelphia water is moderately hard. This problem might be a precipitation of calcium carbonate that is causing the cloudiness. Any further advice appreciated. - David Lyga

 

[jeffreyg]

A couple of years ago I went back to Dektol and also get a clear solution. I have never tried D-72. Why not try mixing it with distilled water and storing in a glass container to see if there is a difference? My house is on well water that is treated with a home system and although soap lathers just fine I don't know what the chemical contents are. Our second well for the pool and sprinkler system doesn't go through the other system and contains enough iron and probably calcium carbonate to be noticeable. I suppose that despite the difference in my two systems the undesirable properties are still present but greatly reduced. We have no chlorine added which could be a factor in your municipal system. The way they treat the water could vary at different times of the year.

We drink bottled water just in case.

http://www.jeffreyglasser.com/

 

[desertrat]

When I mix D-72, it gets slightly cloudy right after I add the sodium carbonate. I think this is because the carbonate contains a small amount of insoluble material. I use Ph-plus, a swimming pool chemical that is sodium carbonate but probably also contains a small amount of impurities. After the solution sits a few hours, it gets a lot more cloudy. This may be from some reaction between some of the ingredients or between some of the ingredients and impurities in the well water or other ingredients. After a couple of days the suspended insoluble material settles to the bottom of the container as a thin layer of precipitate, and the solution is clear. The clear solution seems to work as it should.

But I seldom mix D-72 this way. Usually I mix it from dry chems at tray dilution and use it right away even though slightly cloudy, and it seems to work as it should.

 

[Gerald C Koch]

The cloudiness is due to calcium ion being precipitated as calcium carbonate. There are two ways of preventing this. You can boil the tap water and allow any precipitate to settle overnight and then decant the clear water for use in developers. This removes the temporary water hardness. 5 to 10 min of boiling should do it. The other method is to use a chelating agent. Calgon (Kodak Anticalcium #1 or sodium hexametaphosphate) is a cheap and effective sequestering agent. Use 2 to 5 grams per liter of D-72 depending on the hardness of your water.

 

[Nicholas Lindan]

Along with S. Hexametaphosphate you can use EDTA.

Don't use the Calgon found in the laundry aisle. It used to be SHMP but isn't any longer, although SHMP is still refered to as "Calgon". Laundry Calgon is something else now, and it stinks to high heaven with the usual gag-me-with-a-spoon laundry scent [designed to keep men out of the laundry room, near as I can figure]. Soap is chemically related to Estrogen, Cholesterol to Testosterone - makes sense to me.

When making up stock, adding a teaspoon / gallon of either SHMP or EDTA will take care of the problem.

--

Looked up the MSDS for the current incarnation of Calgon:

Carbonic Acid
Sodium Citrate
Sodium Sulfate

 

[Doremus Scudder]

... and it stinks to high heaven with the usual gag-me-with-a-spoon laundry scent [designed to keep men out of the laundry room, near as I can figure]. Soap is chemically related to Estrogen, Cholesterol to Testosterone - makes sense to me.

Nicholas,

This is the funniest thing I've read in weeks. Thanks.

David,

You are getting calcium carbonate cloudiness. Using distilled or demin water should solve your problem.

Best,

Doremus

www.DoremusScudder.com

 

[David Lyga]

Thank you all: I will try what you have recommended. But, Gerald Koch, I have already tried adding Kodak Anti-Cal to no effect. I will try boiling the water.
I, stupidly perhaps, would have no idea how to get ahold of either EDTA or SHMP. - David Lyga

 

[Gerald C Koch]

Beside Calgon the following chemicals can be used to sequester calccium. Sodium tripolyphosphate and sodium tetraphosphate. Some sequestering agents are available from www.chemistrystore.com. They are quite reasonable and this company also sells several chemicals of interesst to photographers. These chemicals belong to a class of compounds called condensed polyphosphates.

 

[Gerald C Koch]

I have already tried adding Kodak Anti-Cal to no effect.

The amount of Anti-Calcium used depends on the pH of the developer. More is needed for D-72 than for D-76. How much did you use?

 

[David Lyga]

Gerald (and others): I have achieved success. I have some old Kodak Anti-Calcium (sodium tetraphosphate) and the trick is to add it to the water BEFORE you add the sodium carbonate! If you add it AFTER cloudiness results there will be no effect.

This past weekend I did lots of experimentation and got the requirement down to an astounding 0.1 g sodium tetraphosphate per liter of developer. You have to 'prepare' the water this way and I did this many times to confirm my results. I mixed one gram of the sodium tetraphosphate into 100ml of water to make a stock solution. Then I add 10ml of this stock to one liter of water to prepare the water, then add the chemicals for the developer (yes, even for an alkaline paper developer). I am truly amazed with how clear, suddenly, both my solutions (and life!!!) have become. Thank you all, especially Gerald Koch.

Since Kodak Anti-Cal is no longer made is there another convenient source? Any way a large supermarket can have this in another product? Or is it necessary to buy it online? I have had a darkroom since I wa 14 (1964) and this discovery is truly revelatory. - David Lyga

 

[Gerald C Koch]

The two suppliers that I use most often are www.chemistrystore.com and www.techcheminc.com. The Chemistry Store sells supplies for soap making but many of the chemicals are also used in photography. For example, sodium sulfite, sodium carbonate, sodium hydroxide, sodium thiosulfate, ... For basic chemicals they are very reasonable. BE SURE TO VISIT THE .COM SITE AND NOT THE .NET SITE WHICH IS ANOTHER COMPANY.

The other company Tech Chem sells photographic chemicals and I buy my metol, hydroquinone, and Dimezone from them.

The price per pound drops very quickly the more that you buy. TCS smallest size of Calgon is 10# for $36.60 while TCI sells 1# for $14.40.

I find The Photographer's Formulary to be overpriced and some of their chemicals of questionable purity.

Calgon and other pyrophosphate chelating agents slowly hydrolyse in solution. Even if 0.1 g/l works you may want to use the amount that Kodak recommends. The speed of hydrolysis is dependant on pH and so faster in D-72 than D-76.

Calgon company used to sell just the pure chemical for clothes washing but the last time I looked they sell onjly the perfumed stuff for personal bathing. This product also contains other ingredients which could harm negatives and prints.

 

[desertrat]

The important thing to realize here is that it's not necessary to obtain sodium tetraphosphate. Sodium hexametaphosphate (industrial calgon) works, is much easier to obtain, and is much less expensive. If the company you contacted is a distributor of laboratory chemicals, that would explain the price. Laboratory chemicals are very expensive.

 

[Gerald C Koch]

Sodium tripolyphosphate can also be used to chelate calcium. The Chemistry Store sells it for $13.40 for 5 pounds.

 

[Doremus Scudder]

I fail to see why one would go to the trouble of buying and shipping yet another chemical (effective or not) even at a "reasonable" price when the entire problem is easily solved by just using de-mineralized or distilled water, which is available at your local supermarket or in vending machines for just a few cents a gallon...

Sequestering agents make sense for big companies producing consumer mixes for which they cannot control the quality of water used for mixing.

You can easily, and therefore do not need a sequestering agent if you just use pure(r) water.

Cheaper and better all around I would think.

Best,

Doremus

www.DoremusScudder.com

 

[David Lyga]

Just seeing all the options.

The cheapest bottled water here in Philadelphia is at the dollar store: $1 per gallon. Certainly that is affordable but I also wanted to read all the options. I always used proprietary formulae (D-76, Dektol) and did not realize that the sequestering agent was already included in the pre-mixed package. Now I know. I was so surprised at seeing the cloudy mixture that I had to nail the reason down. I now have that list of options. Again, thanks all. - David Lyga

 

[Gerald C Koch]

Here is information on four chelating agents for calcium and magnesium

tetrasodium pyrophosphate Na4P2O7 Ca (poor) Mg (very good)
sodium tripolyphosphate Na5P3O10 Ca (good) Mg (good)
sodium tetraphosphate Na6P4O13 Ca (good) Mg (good)
sodium hexametaphosphate (NaPO3)6 Ca (excellent) Mg (poor)