Dissolving 240gr Sodiumthiosufat in 1 liter water...

[light-zone]

Am I the only one who has problems getting the Sodiumthiosufat to

dissolve in 1 liter of distilled water as a part of Pyro PMK Part B?

 

When I ordered the PMK Kit from Photographers Formulary, I had no

problems whatsoever getting the part B to dissolve. Now that I'm

putting the PMK together myself, it's a different story. I'm buying

good quality ingredients and am using distilled water and following

the instructions in Book of Pyro to a "T". The book mentions

alternative methods like heating and or making a higher dilution by

adding more water.

 

How are you guys dealing with it?

 

Thanks,

 

A Pyro newbie

[ed b.]

Part B of PMK contains sodium metaborate, not sodium thiosulfate (hypo). However, you shouldn't have trouble disolving either one. You can heat the distilled water to 80 degrees F to facilitate disolving these chemicals. You will have to stir a lot.

[light-zone]

Of course, I had a brain fart at the moment. I had also put together F24, and in my hurry to post the question, wrote down the wrong ingredient...

 

Sorry

[neil_miller2]

I agree with Ed about the stirring.

 

I use a stirring paddle with a thin, round handle that you put between the palms of your hands then rub them quickly together. The paddle is under the surface and really agitates the solution while the stem is thin enough not to churn a lot of air into the mixture.

 

After I have stirred the solution for 3 or 4 mins I leave it for a time while I do something else, then come back and mix it some more. It usually all goes into solution, but I understand that a little undissolved solids can be filtered out and don't make that much difference if your solution is almost totally saturated.

 

Also, FWIW, are your scales OK? I only ask because I got my wifes digital kitchen scales as a hand-me-down recently. These accurately weighed a 200 gm weight, but my old balance scales made one 200 gm weight weigh more than the other - by nearly 3 gms. Just a thought.

 

Regards,

Neil.

[jim_galli4]

You're worrying too much. Leave those last few particulates overnight and they'll be gone. Even if you want to use it immediately after mixing it won't make a difference.

[light-zone]

I've got a digital scale that is accurate to within a 1/10th of a gram.

The battery is also new (within the past 4 weeks).

 

I just tried making a new solution. I heated the disstilled water and used my blender on a low speed. I added the 300gr Sodium Metaborate slowly and, after it was all in, I let the mixed run for about five minutes. The solution looks better than before, but it's still milky white. Does that sound right? I'm hoping it'll clear in time...

[light-zone]

Jim,

 

is it normal that after letting the solution come to rest, after considerable mixing, the bottom 1/4 of the 1 liter bottle is a fine sediment? It quickly dissipates after shaking, but comes back in time.

 

I'm off to the pharmacy with something I weighed on my scale, and will have them weigh it as well to see if my scale has gone haywire.

 

Thanks Guys

[light-zone]

My scale checks out fine. It's now about 4 hours since I made the B Solution and it's still settling way more than I expected. A real super saturated solution....

I wish I knew what the difference is between what I'm currently using and what is in the B portion of the Photographers Formulary PMK Kit...

[patrick_gainer]

I am curious to know if the metaborate you got is anhydrous. The Handbook of Chemistry and Physics shows both anhydrous and tetrahydrate. If it is anhydrous, you will never get 300 grams to dissolve in a liter, but the saturated solution will work. Years ago I got 25 pounds of Kodalk. The label said the package contained sodium metaborate.4H20 if I remember correctly. It did not say if there were any other ingredients, but law only requires identification of things you wouldn't want to swallow or inhale or that couls be harmful to touch.

I agree with the others who say you are worrying too much. The developer will work, and in any event you will want to test your mixture to mate it to your own methods of exposure and development.

[light-zone]

Sodium tetraborate decahydrate Na2B4O7 10H2O

 

Please remember, I'm in Germany and there are ever so slight differences in the naming of the chemicals. Not all, just a few, and of coourse Sodium metaborate is one of them.... here it seems to go under the nate Sodium TETRAborate instead of METAborate.

 

I'm just not too comfortable using this solution which BTW, is still milky and still forms sediment in the bottom 30% of the bottle. It seems to me it would be like developing my film in sandy water.

 

I've uploaded a picture of the Chemical bottle and the bottle of the

B solution.

 

Thanks again<div></div>

[light-zone]

is the settled chemical, NOT the desk showing through the bottle.

[ryuji_suzuki]

William, sodium tetraborate and sodium metaborate are two different chemicals! Sodium tetraborate decahydrate (Na2B4O7-10H2O) is often called borax and sodium metaborate octahydrate (NaBO2-8H2O) is often called Kodalk or balanced alkali. That's why your solution won't clear. But you can add some sodium hydroxide or even carbonate to make metaborate out of tetraborate, so you don't have to throw out anything.

[light-zone]

I've discovered the samething you mentioned. I never imagined that Sodium Metaborate would be next to impossible to find here in Germany. I have called about 8 major chemical supply houses and not one has it in stock.

 

I found a conversion chart on the web. It said that Sodium Carbonate can be used instead of Kodalk by multiplying the amount of Kodalk needed by 0.59, and the result would be the amount of Sodium Carbonate to use instead of the metaborate.

[jim_galli4]

Hmmmm....that causes me some concern. Unfortunately I only have a general knowledge and am not an expert. First, sounds like your conversion might be for solubility. Which would explain why the borax wouldn't all disolve but Kodalk would have. Second is I think the Metaborate has a lower PH value than carbonate or borax which the Pyro needs for increased developer agent activity. Chances are that the correct amount of sodium hydroxide might lower your ph to what it needs to be. I hope some of the chem guru's will jump in and be more help.

[ryuji_suzuki]

Here's what you need to do. I assume the original volume is 1.0 liter so if you have different volume just scale to what you have.

 

Get a bigger bottle, at least 2.5 liter.

Pour all you have (240g borax and 1 liter water) in your new bottle. Fill your 1 liter bottle with water and add to new bottle. You want to adjust the final water volume to be 2.2 liter. (2.2 times original volume) Try to dissolve borax as much as you can by shaking dozen times, and wait for a few minutes. Do not heat. Slowly, and carefully dissolve 50 g of sodium hydroxide (NaOH) to this 2.2 liter solution. Gently shake a few times, and if the solution is hot (because dissolution of NaOH gives off heat) cool it down. If you still have some precipitation, you should be able to clear by shaking a few times.

 

Basically, you should dilute and add sodium hydroxide. I recommend to use eye protecting gogle when handling NaOH. This process will yield more than double the amount of sodium metaborate solution than you planned, but as long as you keep it free of air (stay away from CO2 in the air) it will last long.

 

I don't recommend that substituion entirely with sodium carbonate. They are not the same.

 

Jim, I am afraid that metaborate is a stronger base than borax, and sodium hydroxide is one of the strongest base used in photographic chemistry. Addition of NaOH will increase the pH in the step I described above.

[light-zone]

In school I was never much for chemistry. I was the "Artist". If I had only known how valuable it would have been ,I would have paid better attention.

 

Thanks for all the valuable information!