Photo Engineer
Subscriber
Patrick;
To start with, you have said you purify borax by making a saturated solution and decanting the concentrated supernatant. The impurities are concentrated (hopefully) in the solids at the bottom of the beaker. Well, in a later post, you remark on how your developers are often cloudy with an unfilterable suspension. This indicates a contradiction in that the impurities are still somehow present.
So, with a cloudy developer that is not filterable, how to test.....
First make a reference developer with known good chemicals and which does not form a cloudy solution, and run some exposed 35mm film through the clear good check develper. Now, mix up the same developer with borax that yields cloudy developer and develop identical exposures in this developer. The next step is to examine prints and photomicrographs of the two 35mm negatives side by side and look for particles trapped in the film processed in cloudy developer. This would be the first and easiest step.
Of course, pH measurements and titration curves of these developers or at least equimolar solutions of the borax would be useful as well. If the buffer capacity or pH is different between the two developers, then it becomes necessary to run sharpness and grain measurements as well. Of course, it would be nice to do them anyhow just for further verification.
Now, to nail it down, a small partial factorial experiment would be useful to see if the two borax samples reacted the same to small fluctuations in the developer formulation, and I would run the experiment several times due to statistical variations that are normal in photographic systems.
Don't forget to include step wedges made using a sensitometer.
That is what I would do to check out my borax or any other critical chemical such as sulfite and etc.
So, that is the basic experiment to do this...... I don't have the time nor a microscope, nor do I have a microdensitometer and some other ancillary odds and ends, but go to it.
And, BTW, what I did at Kodak was more akin to running several grades of chemical purity for comparison, but they discouraged me from going too far, as it had been done before. What we did do was analyze every incoming chemical and reject those that were sub standard based on the tests run by the Analytical Chemistry Division and left us to the "real" work which involved designing the new chemistry and reading their reports.
Now, to a specific example of all of this especially for Alan..
Imagine that someone untrained in chemistry and physics, but well intentioned, comes to you and tells you that he has been playing around in the lab and has found that gases do not obey the laws established by Boyle and Charles, ie. PV = NRT.
He tells you that increasing temperature causes a decrease in volume! Will you go out and prove him right or wrong? Will you ask him if his gas volume returned to the original volume when returned to the original starting temperature? If you ask him the latter, what if he tells you that he never bothered to check that out....?
Then you might conclude that his increase in temperature introduced a leak around a gasket and he lost some gas. Since there was no check, you can't prove anything to him! What use was the experiment?
I might remark that when I was in the AF, we used photograde chemistry to scratch mix almost everything. At one time, they complained about a bad odor in the HQ, but things "looked" ok. I opened the drum and found that the HQ was contaminated with quite a bit of green crystals and the HQ had a strong odor. It was Quinone.
We returned the batch with a complaint, but in this case the level and nature of the contamination did not cause a serios effect. So, sometimes you squeak by.
Oh well.
PE
To start with, you have said you purify borax by making a saturated solution and decanting the concentrated supernatant. The impurities are concentrated (hopefully) in the solids at the bottom of the beaker. Well, in a later post, you remark on how your developers are often cloudy with an unfilterable suspension. This indicates a contradiction in that the impurities are still somehow present.
So, with a cloudy developer that is not filterable, how to test.....
First make a reference developer with known good chemicals and which does not form a cloudy solution, and run some exposed 35mm film through the clear good check develper. Now, mix up the same developer with borax that yields cloudy developer and develop identical exposures in this developer. The next step is to examine prints and photomicrographs of the two 35mm negatives side by side and look for particles trapped in the film processed in cloudy developer. This would be the first and easiest step.
Of course, pH measurements and titration curves of these developers or at least equimolar solutions of the borax would be useful as well. If the buffer capacity or pH is different between the two developers, then it becomes necessary to run sharpness and grain measurements as well. Of course, it would be nice to do them anyhow just for further verification.
Now, to nail it down, a small partial factorial experiment would be useful to see if the two borax samples reacted the same to small fluctuations in the developer formulation, and I would run the experiment several times due to statistical variations that are normal in photographic systems.
Don't forget to include step wedges made using a sensitometer.
That is what I would do to check out my borax or any other critical chemical such as sulfite and etc.
So, that is the basic experiment to do this...... I don't have the time nor a microscope, nor do I have a microdensitometer and some other ancillary odds and ends, but go to it.
And, BTW, what I did at Kodak was more akin to running several grades of chemical purity for comparison, but they discouraged me from going too far, as it had been done before. What we did do was analyze every incoming chemical and reject those that were sub standard based on the tests run by the Analytical Chemistry Division and left us to the "real" work which involved designing the new chemistry and reading their reports.
Now, to a specific example of all of this especially for Alan..
Imagine that someone untrained in chemistry and physics, but well intentioned, comes to you and tells you that he has been playing around in the lab and has found that gases do not obey the laws established by Boyle and Charles, ie. PV = NRT.
He tells you that increasing temperature causes a decrease in volume! Will you go out and prove him right or wrong? Will you ask him if his gas volume returned to the original volume when returned to the original starting temperature? If you ask him the latter, what if he tells you that he never bothered to check that out....?

I might remark that when I was in the AF, we used photograde chemistry to scratch mix almost everything. At one time, they complained about a bad odor in the HQ, but things "looked" ok. I opened the drum and found that the HQ was contaminated with quite a bit of green crystals and the HQ had a strong odor. It was Quinone.
We returned the batch with a complaint, but in this case the level and nature of the contamination did not cause a serios effect. So, sometimes you squeak by.
Oh well.
PE