Calgon is Not Sodium Hexametaphosphate

[dancqu]

Some interesting fog reduction experiments in a recent
thread demonstrated "Calgon" to be an effective fog
suppressent. Some weeks ago I came across the
New "Calgon" and it's make-up. Now I can't
find it. Anybody know. Dan

 

[Lee L]

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

Lee

 

[Tom Hoskinson]

Some interesting fog reduction experiments in a recent
thread demonstrated "Calgon" to be an effective fog
suppressent. Some weeks ago I came across the
New "Calgon" and it's make-up. Now I can't
find it. Anybody know. Dan

Yes, the product currently called "New Calgon Water Softener" in the USA is phosphate free. The same product is called "Original Calgon" in the UK.

The main ingredients of both of these Calgon products are:

Sodium carbonate
Trisodium citrate dihydrate
Sodium sulfate

See:
http://householdproducts.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&id=18001030

This stuff doesn't sound very useful for photography.

BTW, I still have a large box of the Calgon water softener product that is Sodium Hexametaphosphate.

 

[dancqu]

I see nothing in that list which would explain the
fog suppression reported by psvensson.

I might add, an odd ingredient that carbonate for a
product supposed to complex with calcium. Dan

 

[Tom Hoskinson]

"I might add, an odd ingredient that carbonate for a
product supposed to complex with calcium."

Yep!

The implication is that the Trisodium citrate dihydrate will dissolve/complex with calcium. The Calgon manufacturer warns that this particular Calgon product is designed specifically for washing machine use and should not be used in any other application.

If you want to buy sodium hexametaphosphate, you can find it at The Chemistry Store, Photographers Formulary, etc.

 

[psvensson]

Interesting. Whatever it is, it's doing something!

 

[Tom Hoskinson]

Interesting. Whatever it is, it's doing something!

Yes, interesting!

What is the source of your Calgon and how old is it?

The generic Calgon Trade Name is currently applied to a rather large number of Calgon products with very different chemical attributes.

 

[Tom Hoskinson]

Trisodium citrate dihydrate

This information is from: Dead Link Removed

Trisodium citrate dihydrate is widely used in foods, beverages and various technical applications mainly as buffering, sequestering or emulsifying agent.

• chelates calcium
• buffers pH
• maintains stability of active ingredients
• adjusts pH and forms metallic complexes in photo chemicals

Trisodium citrate dihydrate occurs as white, granular crystals or a white, crystalline powder. It is an odourless substance with a pleasant, salty taste. It is slightly deliquescent in moist air, freely soluble in water and practically insoluble in ethanol (96%).

Trisodium citrate dihydrate is a non-toxic, neutral salt with low reactivity. It is chemically stable if stored at ambient temperatures. Although it is not very hygroscopic, caking may occur upon prolonged storage at humidities higher than 70%. Trisodium citrate dihydrate is fully biodegradable and can be disposed of with regular waste or sewage according to local legislation.

In Europe, trisodium citrate is listed as generally permitted food additive (E 331) and may be added to all foodstuffs, following the "quantum satis" principle, as long as no special regulation restricts the use.

The US Food and Drug Administration (FDA) affirmed trisodium citrate as GRAS (generally recognized as safe) and permitted the use in food according to current GMP (CFR § 182.1751), without setting an upper limit.

 

[psvensson]

Thanks, Tom! I guess it doesn't look like a stretch to imagine that the citrate chelates silver.

The Calgon I used is of recent make. It says that it contains no phosphorous.

Here's the formula I used:

2 tbsp Diamond kosher salt
1/2 tsp Arm & Hammer Washing Soda
8 ml Calgon
2 g ascorbic acid
5 ml phenidone 1% in rubbing alcohol
1l water

Develops Tri-X in about 10 mins at 71F. It gives fairly fine-grained results, but not as fine as one that uses sulfite instead of salt.

The amount of Calgon appears to be close to the minimum: if I halve it, I start get dichroic fog.

 

[Kirk Keyes]

Have you been keeping control (i.e. checking) the pH of your developer? The trisodium citrate dihydrate may be lowering the pH of your developer and thereby lowering the fog level because of decreased activity...

Kirk - www.keyesphoto.com

 

[psvensson]

No, but I think the Calgon is alkaline. Note the carbonate content. It has that soapy feel to it too. If it lowered pH meaningfully I'd think I'd notice a reduction in activity.

 

[gainer]

Thanks, Tom! I guess it doesn't look like a stretch to imagine that the citrate chelates silver.

The Calgon I used is of recent make. It says that it contains no phosphorous.

Here's the formula I used:

2 tbsp Diamond kosher salt
1/2 tsp Arm & Hammer Washing Soda
8 ml Calgon
2 g ascorbic acid
5 ml phenidone 1% in rubbing alcohol
1l water

Develops Tri-X in about 10 mins at 71F. It gives fairly fine-grained results, but not as fine as one that uses sulfite instead of salt.

The amount of Calgon appears to be close to the minimum: if I halve it, I start get dichroic fog.

I think Ryuji is right in saying salt and sulfite are not as predictable as some would have you believe. When I did the experiments for the article "Salt to Taste" I got reduced grain in D-23 with pure salt but not the knd of grain you would want. Resolving power was actually reduced. Rodinal responded about that way to sulfite, and didn't do much of anything with salt.

The carbonate in Calgon is not intended to Chelate calcium. Calgon is a detergent, after all, in which the carbonate is the soapy part. The rest is to keep calcium in the water supply from precipitating the carbonate and leaving the dreaded film on the glassware.

 

[dancqu]

Two fogy; dichroic and chemical. I thought the same but
the quantity, 1 or 2 grams, too little. So I thought, what is
in Calogen that might give a bromide effect?

Well it's dichroic and citrate may do it. Counter productive,
I'd say, salt and citrate. Dan

 

[dancqu]

S&H $5 from www.microessentiallab.com . Dan

 

[Tom Hoskinson]

S&H $5 from www.microessentiallab.com . Dan

Good advice IMO, Dan.

 

[Ryuji]

Are you talking about developer fog or dichroic fog. They are different. Do you see different colors depending on the reflected or transmitted light? Sometimes dichroic fog may look like somewhat rainbow color hologram, or oily film on water.

Citrate can form very weak complex with silver but it's way too weak that it is practically negligible. In a rather crude classification, Ag+ is a weak Lewis acid, and carboxyl group of citrate is a strong Lewis base. They don't complex strongly. Strong Lewis bases are more likely to complex with strong Lewis acids.

If the problem is really dichroic fog, simple salt effect might have done something. Sometimes different temperature, agitation technique, etc. make difference.

 

[dancqu]

QUOTES are from RYUJI:

"Are you talking about developer fog or dichroic fog." If the
first we are back to the Calgon.

"Citrate can form very weak complex with silver but it's way
too weak" Way too weak to counter it's insoluable character
in the presence of chloride, carbonate, and even as an
ascorbate.

"If the problem is really dichroic fog, simple salt effect might
have done something." Im rooting for chemical fog.
I'll have played a Key role in establishing a New
Fog Fighter; Calgon. Dan

 

[Tom Hoskinson]

Chemical Fog is what were dealing with IMO, not Dichroic Fog.

 

[Ryuji]

I don't know what you mean by chemical fog. Can you explain what kind of fog it is?

Usually the term chemical fog is used when a fogging agent is added (for the purpose of fogging). That's not the case here.

 

[gainer]

It used to be that the water softener part of Calgon was separately available as Calgonite. Maybe that's what you need. How it would reduce chemical fog, I don't know. I have used it when I wanted to use my well water in a developer with carbonate. When I used it, it was a phosphate. It looks to me like the current version of Calgon would substitute for both the water softener and developer alkali in something like D-72.

 

[dancqu]

I think the types of fog are not, in one word, well defined.
I'm by no means an expert on the various fogs. But, other
than light fog, non-image exposure to light, I think they
are all of a chemical nature. That includes dichroic fog,
over active developer fog, fume fog, and likely one
or two more fogs.

The important point to remember is the disappearance
of whatever fog on the addition of 8 ml of Calgon. We've
not solved the mystery. If we knew THE fog involved it
would help. Dan

 

[Tom Hoskinson]

I don't know what you mean by chemical fog. Can you explain what kind of fog it is?

Usually the term chemical fog is used when a fogging agent is added (for the purpose of fogging). That's not the case here.

Sorry, I should have been more explicit. I meant the increased (above normal base) fog level caused by too active development, usually controlled by adding a restrainer like KBr or Benzotriazole.

It would help if we knew the pH of the developer before and after the addition of the Calgon.

 

[Ryuji]

I think the types of fog are not, in one word, well defined.
I'm by no means an expert on the various fogs. But, other
than light fog, non-image exposure to light, I think they
are all of a chemical nature. That includes dichroic fog,
over active developer fog, fume fog, and likely one
or two more fogs.

There are many kinds of fog. One kind is emulsion fog, where development center is somehow created on grains, so that they develop in absence of light exposure. There are way too many causes for this to happen, and history of silver gelatin emulsion is in one sense fight against fog. Bad emulsions can have fog right out of the kettle (reacting vessel). Emulsion fog can be caused by continued chemical reaction (sensitization reaction) during storage, naturally present radiation, etc. Then the coated material can be fogged by inadvertent exposure to light. These kinds of fog hcannot be effectively overcome by adding bromide or any other antifoggant to the developer. IF the fog isn't too bad, they may give you false sense of killing the fog, but that is because development is not complete.

Fog can be caused by overactive developer. If the reduction potential of the developer is too close or above the energy level of the conduction band of the silver halide, electron can be injected to the valence band without latent image, and the grain will be developed whether exposed or not. This nonspecific development of grains is called developer fog, and it's a sign of poorly designed developer. But this developer fog can be intentionally caused in, for example, second developer in b&w reversal process. Unrestrained developers may not be good enough for this purpose, and fogging agent like dimethylaminoborane is used. Some labile sulfur compounds are also active chemicall fogging agents. Sodium sulfide, polysulfides, or thiourea in alkaline solution can do this. Film or paper can be exposed to gaseous hydrogen sulfide for same effect.

Dichroic fog is caused by a different mechanism. This is caused when there is a high concentration of soluble silver complex and reducing agent is present. The silver is very often formed where diffusion is limited, i.e., near the surface of the coated material.

Anyway, when fighting with fogs, it is very important to know what kind of fog it is, caused by what mechanism.

 

[Ryuji]

I meant the increased (above normal base) fog level caused by too active development, usually controlled by adding a restrainer like KBr or Benzotriazole.

It would help if we knew the pH of the developer before and after the addition of the Calgon.

I see. In order to test whether Calgon is really an antifoggant, it is crucial to test at a controlled pH.

 

[edz]

Some interesting fog reduction experiments in a recent
thread demonstrated "Calgon" to be an effective fog
suppressent. Some weeks ago I came across the
New "Calgon" and it's make-up. Now I can't
find it. Anybody know. Dan

This confusion, I think, is caused by the use of the name Calgon. In the formulas (many German in origin) the term "Calgon" is used for Natriummetaphosphat (Sodium metaphosphate). The branded tradename "Calgon" of the Benckiser company goes back to their inclusion of the tradename "Calgon" for the substance "calgon" (Hall's "Calc [be] gon[e]") in the German trademark registry in 1934, its market popularity and low cost--- one should in this regard also consider that the Calgon brand of products did not start to be exported to North America untill 1960. Calgon in the context of [photo]chemistry should always refer to the substance originally intended "Natriummetaphosphat" phostphate salts and never any of the products with the "Calgon" brand. This is, for instance, much like the term "Kleenex" which is used to denote nearly any standard facial tissue in North America. The brand "Kleenex"[tm]--- a term which is occupied by the word "Tempo" in German, a brand started in 1929 by the Vereinigten Papierwerke Nürnberg but today owned by Procter and Gamble--- also includes, however, a whole array of papers from kitchen to toilet. This practice is wide spread reflecting the power of branding during the phase of early market adoption: In the UK one uses the term "Hoover", for instance, to refer to any electric vacuum cleaner and hardly those from the Hoover company. Sometimes the development of brand into term is so strong that the brand does not even have to be available to still be used. The word "Chiclet" used in many parts of the world to denote "chewing gum" comes to mind. The brand too can develop and these are many examples of items whose current market is irrelated to the original placement.