Using less than total package quantities

Developers are an unstable mixture. As soon as the powder is exposed to the air and humidity iy begins to decompose. Transferring the contents to jars helps but even so the damage in the form of moisture has already begun.

This week I tried to see how little water I could use to dissolve D-76, on the theory that a more highly concentrated working solution would last longer in storage. It didn't work at all and I ended up just mixing a full gallon. I then split the results into 4 1-qt datatainer bottles, filled near the top, and squeezed just a bit to set up a negative pressure in the bottle. 1-qt size fits my processing habits nicely. Per helpful suggestions in another thread, the bottles are on the shelf in the basement, which stays in the 70'sF in the summer.

pbromaghin said:

This week I tried to see how little water I could use to dissolve D-76, on the theory that a more highly concentrated working solution would last longer in storage. It didn't work at all and I ended up just mixing a full gallon. I then split the results into 4 1-qt datatainer bottles, filled near the top, and squeezed just a bit to set up a negative pressure in the bottle. 1-qt size fits my processing habits nicely. Per helpful suggestions in another thread, the bottles are on the shelf in the basement, which stays in the 70'sF in the summer.

Click to expand...

The problem with doing this that you will be near the solubility limit. If the temperature drops components will start to crystallize out. The crystals can be very hard to redissolve in particular the metol

The solution to all this is to only buy enough to fit your usage. Why is this so difficult.

I only use partial mixing for liquid photographic chemicals.

Gerald C Koch said:

The problem with doing this that you will be near the solubility limit. If the temperature drops components will start to crystallize out. The crystals can be very hard to redissolve in particular the metol

The solution to all this is to only buy enough to fit your usage. Why is this so difficult.

Click to expand...

My desire was to find the solubility limit, and through direct experimentation I succeeded in finding that it offered no advantage over Kodak's recommendation. Wanting to buy to fit my usage is all well and good until it bumps into the realities of the quantities available.

Puggsy said:

A noobie post!
I have in the past divided Lith powder developers (Part A&B) with never a problem.
As a retired pharmacist I cannot see a problem with dividing powders if the powder has been mixed or stirred to become as close to homogeneous as possible (ie. acceptable tolerance).
In my profession I have packed headache powders in paper wrappers from bulk powder mix (many years ago!). All tablets are pressed from a small sample of a large powder mix. All the same principles apply to dividing up 'dry' photo chemicals. Deterioration from oxidation, humidity, etc, are other problems to consider if the original pack has to be opened.

Click to expand...

So would you agree with my method to devide powder developer I descibed before ? I ask my wife - she has worked as a pharmacist for many years.
But she has got no answer to me ...
And she has thrown away her complete
antic messurement equipment as she desided she will not need it anymore.....?
I didn't know this - as I was informed about it was to late.
So this method comes from my own thoughts.The only problem with mixing
powder is the fact that the smalest parts of powder are most on the botton.
But this method will awoid it.
Do you agree with - in concern to statistical normal distribution?

with regards

To my wife this issue seams to be to much complicate... - she
is more in concern of digital messurement and analysis methods. ....
this is to complicate to me .

Gerald C Koch said:

Developers are an unstable mixture. As soon as the powder is exposed to the air and humidity iy begins to decompose. Transferring the contents to jars helps but even so the damage in the form of moisture has already begun.

Click to expand...

But compared with best stored liquid
solutions it should be no problem at -
shouldn't it ?
Some chemical compounds began to oxidize just at the moment they are in contact with air (ppd for example) within
days or weeks they changed their surface
color.
But most chemicals are quite stable.To
avoid moisture is nearly easy.
Do you not think so ? Handle powder exact like liquid from storage will give them a livetime of decades.
(with possible lost of chemical reaction
potential of some simple percent - after years)
Do you agree - to very most compounds ?

with regards