Figuring dilution for small amount of developer?

[Zelph]

Have directions for mixing one litre of stock solution which is then used in small amounts to make a working solution of developer.

I want to make the working solution without having to keep bottles of stock on the shelf.

Mix calls for 750 grams of chemical and water to make 1 Litre. I want to make 10ml of the solution - so do I put in 7.5 grams of the chemical?

I think it is right - but math, numbers and I don't get along too well and with a recent move some of the charts I have it written on have somehow disappeared.

 

[markbarendt]

Math sounds right.

 

[Ricardo Miranda]

No, wrong if you are talking about the Stock Solution and if that is made of powder chemicals.
Always follow the instructions of the manufacturer to the letter.
Could you clarify what developer is it and what "750 gr of chemicals" is it? Powder?

 

[mgb74]

I believe the issue with powder chemicals is that the different chemical may not per perfectly mixed. So your 7.5g of chemical may not have the same % of each component as the entire 750g container.

 

[Zelph]

Pyrocat HD. Just want to make up Part B for 1:1:100 dilution for one litre of working developer. Or 2:2:100 dilution of working developer. Potassium Carbonate is the power for Part B of the solution.
Since I mix the photo chemicals from scratch - it is not "manufacturer" instructions.
And yes, I can weigh the powder accurately using a scale accurate to +- .001 gram.

 

[markbarendt]

Ricardo is right if you are using a powder that is made up of more than one chemical, like most developer mixes, then you need to mix up the whole batch.

 

[jeffreyg]

Plus 1 on mix the full amount. Use what you need and store the rest of the stock solution in brown glass pharmacy type bottles filled to the top. When I use a pyro developer I use PMK Pyro from Bostick and Sullivan. Liquids "A" and "B" separate bottles and mix as needed. The concentrates last.

http://www.jeffreyglasser.com/

 

[destroya]

i make pyro-hd from scratch also. I make 250ml of the stock solutions. they last for quite a long time. part B will last years based on my usage, so make up 100ml of it, not 10. I would find that almost a waste of time, to measure, weigh and mix every time. 100ml will last 10 liters of stock solution, or 20 rolls of 120 or 30 rolls of 35mm. but its up to you. yes you could make 10ml of part B as its only 1 ingredient

 

[Dennis S]

i make pyro-hd from scratch also. I make 250ml of the stock solutions. they last for quite a long time. part B will last years based on my usage, so make up 100ml of it, not 10. I would find that almost a waste of time, to measure, weigh and mix every time. 100ml will last 10 liters of stock solution, or 20 rolls of 120 or 30 rolls of 35mm. but its up to you. yes you could make 10ml of part B as its only 1 ingredient

That is the way I do it also. Also Propylene Glycol which lasts longer but a friend just uses distilled water which works well for him. You have to be very careful of cross contamination but I use separate everything except for the final mix.