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Ed Bray
9-Dec-2012, 03:07
I have been using Pyrocat HD for a while now and am usually pleased with the results, but I would like to move away from having a stock solution of Part B and making it up as I need. Part A is made in distilled water exactly as described by Sandy King, but as I have an almost infinite stock of Light Sodium Carbonate (Light means anhydrous) I have been using that to make up the Solution B at a ratio of 200g per 1000mls of water, then in use I am using 1:5:100.

I would like to do away with the Stock solution of Part B and just mix the SodaCarb into the distilled water used for developing. So just want to check that I have got the sums right, and would there be any issues from using this process?

So currently I am making up 200g of SodaCarb into 1000mls of water to make a Stock Solution, this means that in each ml of stock solution I would have 0.2g of SodaCarb, as I then use 5x this amount per 100mls of water to make the working strength developer, can I take it that there should then be 1g of SodaCarb to every 100mls of water in the working strength developer?

So what I would like to do is make up a working solution of developer of 800mls for my 3010 Expert Drum (when full), therefore I propose to initially make up 8g of SodaCarb into 800ml of distilled water, when completely dissolved add 8mls of Part A just prior to beginning processing.

Would this work?

TIA, Eddie.

Doremus Scudder
9-Dec-2012, 03:43
"Would this work?"

Short answer: Yes.

Being a bit more exact: 1+5+100=106 --- 106x8=848. If you've been mixing your working solution this way, i.e., 8ml A + 40ml B + 800ml water, then mixing it the way you describe will result in a bit less solution. 800ml water + 8ml A + 8g carbonate would result in 808ml of solution plus whatever volume increase that adding 8g of dry carbonate creates (possibly none). In practice, you may simply be able to ignore the difference. If you wanted to stay precise, you could just top up your solution to 848ml after dissolving the carbonate. If you've calibrated your system precisely, then it would probably be a good idea.

If you've been mixing 8ml A + 48ml B and then adding water to get 800ml total working solution, then simply start with 700ml water, add 8ml A and your dry carbonate and then top up to 800ml after the carbonate has dissolved.


Best,

Doremus

Ed Bray
9-Dec-2012, 04:14
Thanks Doremus, I have not actually used 800ml yet as I have not yet used the 3010 drum. I have used 1:5:100 and also 1.2:5:100 (1.2 was to allow for the slower Unicolor Motor Base) but these would have been 5:20:400 making a total of 425ml in total.

I would like to eventually get repeatable results but with an ease of making up an accurate repeatable developer and to that end would like to standardise the makeup as best I can. I have a very accurate 2ml pipette dispenser so would like to use a multiplication of that for Part A, as well as my original scenario I was thinking of trialing 8ml Part A mixed into 750ml Distilled Water which had been premixed with 7.5g of SodaCarb.

Doremus Scudder
9-Dec-2012, 04:31
If I were you then, I'd just start with 800ml of water, add the dry carbonate, dissolve, and then add 8ml of solution A to make 808ml+. That's closer to the original recipe than your 750ml + 8ml A.

I also might measure out a few batches of 8g of carbonate and put them in small containers (film cans, tiny zip-locs, etc.) so you didn't have to weigh out the carbonate each time.

FWIW, I've been using syringes to measure out small amounts of various chemicals for years now with great results. I have several sizes. With PMK, I have one syringe for sol. A and 1 for sol. B. Easy to dose and wash out and easy to get at the local pharmacist.

Best,

Doremus

j.e.simmons
9-Dec-2012, 05:58
I agree on the amounts. I've been mixing my B solution one shot for years. It works very well and since you are mixing powder directly into the developer, it avoids the possibility of contamination of the A solution. I also agree on the syringes.
juan

mdm
9-Dec-2012, 13:03
I just use washing soda, pentahydrate. 5.4g to make 1 liter at 1:1:100, about double that for 2:2:100

Doremus Scudder
10-Dec-2012, 06:57
I just use washing soda, pentahydrate. 5.4g to make 1 liter at 1:1:100, about double that for 2:2:100

David,

The Pyrocat alternate with sodium carbonate calls for 1 part A solution, 1 gram of sodium carbonate (Sandy King recommends making a 20% solution and using 5 parts as Ed notes above) and 100 parts water. One liter (or up to 1060ml depending on mixing methods) would then have 10g carbonate.

The most commonly used version of sodium carbonate is the monohydrate, which I assume Sandy is specifying for his recipe.

Washing soda is the pentahydrate, as you note, and contains more water. In order to get the same amount of chemical as 10g of monohydrated sodium carbonate, you would need 23.1g of washing soda. The conversion factor is: monohydrate x 2.31 = decahydrate (which is washing soda and the same as crystals).

Bottom line, you seem to be using to little carbonate...

Best,

Doremus

mdm
10-Dec-2012, 21:43
Thanks for that, that explains a few things. It works fine though, just some films I struggle to build enough density for alt prints. Thats probably why my divided pyrocat negatives turned out so thin, but still usable. And why some of my negatives have in the past suffered from defects. Probably why I have got best results mixing at what I thought was 2:2:100.

I have that printed out and I knew that you mixed it 200g/l and I converted correctly, just forgot to use it 1:5:94, didnt read that far with my stressed hurried brain. I have updated my recipie and just as well as I have a set of 8 negatives to develop.

David