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atlcruiser
8-May-2011, 17:29
Hi All,
last week I posted a question about the mix of Sodium Thiosulfate "Plain Fixer" to water to make a plain fixer. I had planned to use it, with the addition of sodium bisulfite in fix one, as a two step fix process.

I mixed 16oz of the Sodium Thiosulfate to 2 liters of water at around 90'. It really did not want to dissolve and eventually did dissolve but I ended up with a very thick liquid that had a greasy feel to it. I did not want to chance a print in it so I swapped back to reqular rapid fixer for the rest of the session with no issues.

Did i mix this wrong? I bought regular Sodium Thiosulfate from e bay listed as for photography. Was the mix i listed above for the concentrate and should I make a working solution from that?

Should I give all of this up and admit defeat? :)

thanks
david

Richard Rankin
8-May-2011, 19:45
When I asked about how to do Sodium Thiosulfate "Plain Fixer" of the folks from Photographers Formulary, they told me:

You want to go by weight so use 15 grams to 100 ml of water to make a 15% solution so 150 grams to 1000ml

So, for 2 liters of 15%, you'd use 300g by weight.

Richard

Leigh
8-May-2011, 20:23
Well, 16oz is roughly 454gm, so in 2 liters that would be about a 22.7% solution.

You're not that far above the desired 15%.

I don't understand why it would be "thick and greasy". Are you sure it was the right stuff?

- Leigh

Jim Shanesy
8-May-2011, 20:42
What you want is sodium thiosulfate pentahydrate rice crystals. The best source I've found for this is the Chemistry Store (http://www.chemistrystore.com/Chemicals_S_Z-Sodium_Thiosulfate_1.html). The 50 lb. bag is the best value. 16 oz. (two cups) dry measure of this per 1/2 gallon of water at 90F will give you the fixer you want. It goes into solution quite easily.

Either your ebay source gave you some other chemical or it's not prismatic rice crystals. I've used hundreds of pounds of this chemical from the Chemistry Store and it makes a great alkaline fixer. I promise. You can't go wrong.

atlcruiser
8-May-2011, 20:46
Thsi is what I bought:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290501341803&ssPageName=STRK:MEWNX:IT

Specifically stated to be:
Sodium Thiosulfate Pentahydrate
Crystals


When I say thick I am not talking maply syrup thick...it was just much thicker than any fixer I have ever seen and it did have a greasy feel to it and was sort of hard to wash off.

Funny enough I bought most of my other stuff at the chemistry store! Maybe I messed up here!

Jim Shanesy
8-May-2011, 20:52
Thsi is what I bought:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290501341803&ssPageName=STRK:MEWNX:IT

Specifically stated to be:
Sodium Thiosulfate Pentahydrate
Crystals

Funny enough I bought most of my other stuff at the chemistry store! Maybe I messed up here!

The Chemistry store is cheaper, even in small quantities. ($2.50/lb. for 2 lb.) I don't know about the greasy feel, since I always have a glove on when I put my hands in it, but it's not particularly thick when mixed.

The picture looks like the right stuff. I would've tried fixing a print with it. In any case 1 lb. certainly won't last very long. Buy 9 lbs. or so and give it another try.

Wayne
8-May-2011, 21:40
Did you use hot water to start?

Ole Tjugen
9-May-2011, 00:14
A strong solution of thiosulfate is a bit viscous. Nothing wrong with it at all.

jnanian
9-May-2011, 04:00
When I asked about how to do Sodium Thiosulfate "Plain Fixer" of the folks from Photographers Formulary, they told me:

You want to go by weight so use 15 grams to 100 ml of water to make a 15% solution so 150 grams to 1000ml

So, for 2 liters of 15%, you'd use 300g by weight.

Richard

exactly -

water is 1g = 1cc(ml)

atlcruiser
9-May-2011, 08:16
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

tgtaylor
9-May-2011, 08:21
To the above I would add the clarification that you would want to add Sodium Thiosulfate to water and then bring up the resulting solution to the desired volume. For example add 15 grams of ST to less than 100mL of water and then bring it up to 100 mL. Only then will you have a 15% solution - 15gms of ST, 85 gms of water.

Thomas

atlcruiser
9-May-2011, 09:18
So my goal is a 15% solution. When I was reading Michaels A Smiths Lodima/Azo techniques he wrote 32oz to 1 gallon that is why I mixed 16oz to 2L. If I go with the 15% solution goal it looks like I made the solution to rich.

thanks

Lynn Jones
9-May-2011, 09:53
You'd better have some Na Sulfite in the solution because it regenerates the thiosulfate. Whatever you do, don't use two bath fixation, lots of films have been destroyed by that silliness. It is a common cause of colloidal sulfur contamination. Always use good fixer, properly. Some replenishment is perfectly acceptible.

Frankly, a good rapid fixer with replenishment will last for a very long time and without serious chemical problems.

Lynn

tgtaylor
9-May-2011, 11:16
Strike ""- 15 gms of ST, 85 gms of water -" in my post above as the solute also has volume. dissolving 15 grams of ST in water and then adding water to bring the volume up to 100 mL will give you a 15% solution but you will have a little less than 85 grams of water as the solute has volume necessarily greater than 1gm/mL.

Thomas

BetterSense
9-May-2011, 11:45
Why could 2-bath fixing possibly cause problems?

Leigh
9-May-2011, 12:15
Perhaps I'm missing something, but it seems that...

given the molecular weight of the pentahydrate as 248.18, and
given the molecular weight of water as 18.015,
thus water constitutes over 36% of the pentahydrate by weight, so...

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.

Yes/no?

- Leigh

Kirk Keyes
9-May-2011, 12:33
150 grams of anhydrous sodium thiosulfate would give a 15% w/v solution when dissolved into 1 L of water.

I've never heard of two-bath fixing ever ruining film. In fact, I've been using it for about 20 years now and never had a sheet (or roll) ruined by it - from colloidial sulfer or otherwise.

I recommend two-bath film fixing as a great way to ensure complete fixing.

Leigh
9-May-2011, 12:36
150 grams of anhydrous sodium thiosulfate would give a 15% w/v solution when dissolved into 1 L of water.
True, but what's being discussed here is pentahydrate, not anhydrous.

That was the reason for my previous post.

- Leigh

atlcruiser
9-May-2011, 12:49
I am strongly in the camp of the 2 fix...it has been done that way for years by many, many folks with no issue especially whwn the sodium bisulfite is added and the fix is swapped. I want to ensure there is nothing left in the paper!

I only do this with FB paper and use rapid fix for all RC papers.

Kirk Keyes
9-May-2011, 13:14
True, but what's being discussed here is pentahydrate, not anhydrous.

That was the reason for my previous post.

- Leigh

Interestingly, heylloyd lists "plain hypo fix" as using 160g anhydrous sodium thiosulfate into 1 liter (along with 30-60 g sodium sulfite).
http://www.heylloyd.com/technicl/plain.htm

eddie
9-May-2011, 13:25
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
9-May-2011, 14:05
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.

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9-May-2011, 14:14
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Leigh
9-May-2011, 14:51
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
9-May-2011, 17:13
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 90F. 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
9-May-2011, 17:19
atlcruiser:

Take a measuring cup and put 2 cups of pentahydrate rice crystals into enough water to make 1/2 gallon at 90F. 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
10-May-2011, 07:03
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
10-May-2011, 07:19
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
10-May-2011, 09:13
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
19-May-2011, 08:24
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.

ZoneIII
19-May-2011, 08:27
150 grams of anhydrous sodium thiosulfate would give a 15% w/v solution when dissolved into 1 L of water.

I've never heard of two-bath fixing ever ruining film. In fact, I've been using it for about 20 years now and never had a sheet (or roll) ruined by it - from colloidial sulfer or otherwise.

I recommend two-bath film fixing as a great way to ensure complete fixing.

Funny, I have been developing film for over forty years and I don't remember hearing of anyone fixing film twice. It is completely unnecessary. Now, with fiber base paper, two fixes is the traditional method. But film? No.

ZoneIII
19-May-2011, 08:29
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

Well said!

Harold_4074
19-May-2011, 10:22
Pure sodium thiosulfate in solution is unstable in the presence of even a weak acid. In my experience, a liter of solution in an open two liter beaker will turn cloudy in a matter of days, due to carbon dioxide having dissolved in the water and formed carbonic acid. (This was a mystery when I first observed it, but a 1937-vintage chemistry text describes it explicitly.) The cloudiness is precipitated sulfur, which could definitely be trapped by paper fibers, probably oxidize to form sulfurous acid, and possibly cause eventual fading of a silver image.

Elemental sulfur is insoluble in water, so washing will remove it only mechanically. However, sulfur reacts with sulfite to form thiosulfate, so hypo clearing agent will (at least theoretically) dissolve it. Ironically, the usual advice is that "HCA is only needed if an acid fixer is used", implying that plain hypo would make it superfluous.

Both alkali and sulfite from developer carryover will tend to suppress the decomposition, so it would seem that the greatest risk would come from fixing in a tray (large surface-to-volume ratio) of pure (no added sulfite or bisulfite) hypo solution following a running-water rinse in lieu of stop bath, particularly in the absence of an HCA treatment before washing.