Sodium Thiosulfate "Plain Fixer" question

[eddie]

just add the fixer to the water slowly and keep stirring. i do basically what you are asking so i think you just added the fixer too fast.

it should not be greasy.

FWIW i add 15g per 100ml....i call it 15%....even if it is not really 15% all will be fine as this is far from rocket science.

eddie

[Ole Tjugen]

The strength of aqueous solutions of solids is usually stated in w/v - weight per volume.

Molarity doesn't enter into it, nor does the different densities, ONLY that if you have 15g of something dissolved in a total of 100ml solution, you have a 15% w/v solution.

But - you have to know what "something" is. Especially since there is a difference between anhydrous and pentahydrate...


Come to think of it, adding 85ml water to 15g sodium thiosulfate (whether anhydrous or not) will give a little LESS than 100ml total solution. So always top off in the end.

[johncina36]

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[Leigh]

I want to ensure there is nothing left in the paper!

But hypo only acts on silver halides, and those are only found in the emulsion, not in the paper.

Archival problems arise when the fixer is not completely removed from the paper during the wash phase.

- Leigh

[Jim Shanesy]

Dissolving 150 gms of the pentahydrate in 1 liter (total volume) of solution would only yield about 10% sodium thiosulfate, the remaining 5% being water contributed by dissolving the crystals.

atlcruiser:

Take a measuring cup and put 2 cups of pentahydrate rice crystals into enough water to make 1/2 gallon at 90°F. Mix well. That's what Michael Smith has been using for over 40 years. None of his prints has faded yet.

I doubt he could tell you the molecular weight of sodium thiosulfate if his life depended on it.

[atlcruiser]

atlcruiser:

Take a measuring cup and put 2 cups of pentahydrate rice crystals into enough water to make 1/2 gallon at 90°F. Mix well. That's what Michael Smith has been using for over 40 years. None of his prints has faded yet.

I doubt he could tell you the molecular weight of sodium thiosulfate if his life depended on it.

That is exactly where I started

I feel like I opened pandoras box !

[Lynn Jones]

Better Sense:

2 bath fixation: I first came across this shortly after WWII when Europe was in a mess. The purpose of it was to first fix in old nearlyexhausted thiosulfate and then fix in fresh thiosulfate fixer, this to extend the life of fixers at a time when supplies were frequently low and always high in price. It seemed like such a good idea until some time later when sulfiding of films and prints destroyed the silver based products.

In near exhaustion, fixation takes place slowly but under those conditions, coloidal sulfur (at that time invisible) absorbs and subsequent fixes and washes will not fully remove it. Hence, oxygen, silver, and sulfur do their brown fugitive magic.

One fresh fixer is always preferable to any other choice.

Lynn

[cyrus]

Better Sense:

2 bath fixation: I first came across this shortly after WWII when Europe was in a mess. The purpose of it was to first fix in old nearlyexhausted thiosulfate and then fix in fresh thiosulfate fixer, this to extend the life of fixers at a time when supplies were frequently low and always high in price. It seemed like such a good idea until some time later when sulfiding of films and prints destroyed the silver based products.

In near exhaustion, fixation takes place slowly but under those conditions, coloidal sulfur (at that time invisible) absorbs and subsequent fixes and washes will not fully remove it. Hence, oxygen, silver, and sulfur do their brown fugitive magic.

One fresh fixer is always preferable to any other choice.

Lynn

I'm very interested in this post Lynn. Are you saying that two-bath fixation promotes sulfiding because of the initial use of near-exhausted fixer?

[Leigh]

I consulted my copy of The Film Developing Cookbook by Anchell for a fixer recipe and was surprised to find the following (page 105):

"The most current research indicates that sodium thiosulfate, the photographer's standby for most of the 20th century, cannot adequately fix modern films or papers. This appears to be due to the increased use of iodide in contemporary films and papers. If an acid fixer is to be used, use only acid "rapid" fixers based on ammonium thiosulfate."

The first quoted sentence includes a note referencing an article published in the Journal of Imaging Technology, vol. 10 no. 1, Feb 1984.

- Leigh

[ZoneIII]

Thanks all...I did mix it a bit strong at 16oz to 2l of water. I will trash what i have and mix again.

I did mix it at about 90'. I think all is well and maybe I was a bit slow on the uptake

I realize that it's too late, but for future reference, if you mix it to too high of a concentration, there's no need to "trash" it. Just dilute it util it is the correct concentration.