How to mix Powders

[Reticenti]

I bought powdered chemicals (Ilford ID-11) since it was cheaper than the liquid. Now my question is: How do I dilute a powder to a certain dilution. Lets say I need a 1+3 dilution and need to make 500ml. Would I weigh out 125 grams of the powder and add the rest in water, since water is 1g/mL? Also, how much would I add of each packet, since there is an A and B packet.
OR, do I just make up a stock solution of everything and go from there?

Thanks

 

[Michel Hardy-Vallée]

You always make a stock solution when you work from commercial powder packages. They contain many different chemicals together, and there is no a priori guarantee that they are equally dispersed. If you worked from raw chemicals and a scale, then you could easily measure your working solution each time.

 

[Reticenti]

This makes sense.
Thanks

 

[Sparky]

You'd even be surprised how inconsistent a liquid mix can be! Definitely do it in aqueous solution. Don't mess around with powder, unless you're ADDING it together. Never divide though.

 

[Tony Egan]

I use the bladders from 5 litre wine/water boxes to store stock chemicals. The bladders shrink as chemicals are used reducing the amount of air in the bladder. I find it a very secure way to store and chemicals keep very well. Much better and cheaper than the plastic concertina bottles in my experience. I also use them for working strength fixer measuring out and refilling the bladder as required. Good luck.