TS-4 Odorless Stop Bath

[al olson]

I can't find any posts under 'TS-4' or 'TS4' so I am posting my problem here. Recently while ordering chemicals from Photographers' Formulary, I opted to try their TS-4 Odorless Stop Bath. I ordered the 10 liter size thinking I would first mix a stock solution and then dilute it to a working solution as needed.

The problem is that the stop bath comes in powdered form and the instructions are to mix with 10 liters of water. I know that subdividing the powder is not recommended because the mixtures are not homogeneous. I don't have any 10 liter containers, nor do I want any. I want to use it one liter at a time.

So my question is, is it possible to mix TS-4 as a 1 gallon stock solution for further dilution as a working solution? Has anyone had any experience with this problem?

[Erik Larsen]

Hi Al, maybe try and dissolve the entire contents in the least amount of water you can for a stock solution and figure out you dilution from there. It might dissolve in a gallon maybe?
Good luck
Erik

[nolindan]

Subdividing the powder can work quite a bit better than you might think. It works best with Kodak powders - Kodak adds/coats/hypnotizes chemicals so they mix well as powders and stay mixed. Typically powders are formulated all mixed together in large vats and then placed in the individual packets.

A small producer may formulate each packet individually, but this would drive costs through the roof for all but the simplest chemistries.

As for TS-4 the MSDS says that it is composed of a single chemical - whose identity is a 'trade secret' - so there shouldn't be a problem dividing the powder. The MSDS also specifies a solubility of 50g/l @20C. From the size of the 10L packet you should be able to figure out the minimum mix volume (probably a good idea to keep things safe - say no more than 30 or 40 g/l).

A few candidates for the 'secret ingredient':



Property
TS-4
Citric Acid
Boric Acid


Sp. Gravity g/cc
1.51
1.66 (1.5*)
1.44


Melting Pt C
170 - 185
153
171


Solubility g/l
48.8
73
48.8 (47.2**)


*Monohydrate; **48.8 in Boric Acid MSDS, 47.2 in Wikipedia

Chances are that PF stretches some of the properties to keep their secret ingredient a secret.

Although Boric Acid looks close, the MSDS effects of TS-4 don't match those of Boric Acid - and I have no idea at all if Boric Acid would even work as a stop bath, I just pulled it out of my arse as a weak acid found in photographic use.

As others have mentioned, Citric Acid would work as well as anything for an oderless stop.

Me, I like the smell of Acetic Acid in the morning.

[tgtaylor]

Al,

I'm not familiar with the TS-4 Stop Bath - I thought that you were refering to TS-4 fix - but I'd call them up and see if you can mix it in small quanities. Seems to me you should. If not, then maybe they will swap it out for Citric Acid. One pound of citric will make 30 liters of odor free stop and cost just $6.95. That works out to 23 cents/liter. I use 1500mL for a printing session which processes as least as many prints as does developer (Dektol) and fix (TF-5).

Thomas

[al olson]

Thanks for the research, Nicholas, I think I will opt for the assumption that it is citric acid (solubility 73 g/l).

I weighed the packet and found that it is 300 g. Dividing 300 by 73 gives me 4.11 liters, a little more than one gallon, but one gallon jugs are the largest I have.

I will warm up the water to see if more of the chemical will dissolve in a one gallon stock solution. If it does not all dissolve, then when I mix my working solution I will shake the jug until the undissolved powder is in suspension, then measure out the amount. If this doesn't work, I am only out $10 plus shipping.

I am surprised that the photo stores (Denver Pro Photo) do not at least sell 5 liter jugs since that is the size of many of the popular chemical kits today. The largest they have are one gallon and almost no chemical is sold in quart or gallon quantities any more.

Thomas, I think that PF uses the TS designation for stops and TF for fixes.

[nolindan]

I think I will opt for the assumption that it is citric acid (solubility 73 g/l) ... I weighed the packet and found that it is 300 g. Dividing 300 by 73 gives me 4.11 liters ...

Ooops - mistake in that table - that's 73g/100ml for Citric Acid - or 730g/l - I should know better ... one can almost make citric acid into a syrup.

So, from the MSDS it definitely isn't Citric Acid - though that was my first guess also. The physical properties listed are too different and the list of health effects are nothing like those of citric acid - the ingredient in TS-4 appears to have some CNS activity and seems rather nasty.

The chances are that the MSDS solubility is correct - around 50 g/l - and assuming 73 g/l is going to leave you with 1/3 of it at the bottom of a 1 gallon jug. I would suggest dividing the powder and using two 1-gallon jugs or dividing it 2/3 - 1/3 and using a 1-gallon [4l] jug and a 1/2-gallon [2l] jug.

[tgtaylor]

Instead of mixing up and storing a stock solution, I mix a working solution as needed: 15gm citric acid/Liter for a 1.5% working stop.

Thomas

[Richard Wasserman]

Instead of mixing up and storing a stock solution, I mix a working solution as needed: 15gm citric acid/Liter for a 1.5% working stop.

Thomas


Me too—1 tablespoon is basically 15 grams. Very easy!

[al olson]

Thomas and Richard,

I presume that the citric acid that you mention is not the same as TF-4. The TF-4 package weighs 300 g. That means that the amount would 30 g. per liter to make up the 10 liters, not 15 g.

Nicholas,

You say the ingredients of TF-4 are rather nasty. Hmmm, any worse than acetic acid? Maybe this odorless fix is not the best choice.

Otherwise I think that based on solubility my best approach is to divide the powder in approximately one half and dissolve each half in one gallon of water. Then (assuming that the chemicals are not homogeneous) to mix the working solution when needed roughly in the ratio of 3:3:2, where the first two numbers are the amounts from each jug (one gallon equals 3.785 liters) and the last is the added water. That is to take 375 ml from each jug and add 250 ml of water for the working solution.

[Doremus Scudder]

You guys need to get straight on the difference between TS-4 and TF-4.

TS-4 is an odorless stop bath (the "S" is for "Stop"); TF-4 is an alkaline fixer (the "F" is for "Fixer")

Whatever the chemicals in the TS-4, the solubility is listed on the MSDS as "4.88g / 100g H20 at 20°C." 100g of water = 100ml of water by volume at 20°C, so:

48.8 grams of whatever it is will dissolve in one liter of water. Look at the (metric) weight of the 10-liter package you have and divide it by 48.8. That will give you the number of liters you need to make a concentrated solution.

If the volume of the concentrated solution is less than 10 (and it likely will be), then figure out your dilution ratio for mixing a working solution. Example: your package will dissolve in 2.5 liters of water. 2.5 + 7.5 = 10, so your ratio is 2.5+7.5 or 1+3. Or: if it all dissolves in 2 liters, then 2+8 or 1+4 is your ratio, etc.

If your package will dissolve in an oddball amount of water, you might consider mixing the next-greater easier-dilution-ratio amount (e.g., if you could dissolve it all in 2,33 liters, maybe mixing 2.5 liters so you could easily dilute 1+3 to make the working solution might be the more convenient choice).

Another approach, and one I might use if the powder is homogenous, is to figure out how many grams of powder you need per liter of working solution by simply dividing the weight of the contents by 10 for your 10-liter package. If you have a scales, just weigh out what you need for a liter once, dump it in a graduate and note the volume. If the package contents stay the same (i.e., don't clump up with hydration, etc.) then you can simply use the volume measure to make the desired amount. Yes, weighing would be more accurate (and a more accurate method if you want to take the time), but a rough volume measure should be precise enough for a stop bath.

Best,

Doremus