The purpose pf the patent system is to protect a person's interest in his own discoveries and designs without having to resort to secrecy. Now you read a patent disclosure and see that the range attempted to be controlled by the disclosure is so great that there has been no true disclosure. The patent I have read, about stabilized black-and-white developing compositions and methods of use, is a case in point. A manager, I reckon, gave these two experimenters a task to perform in as many different ways as they could think of. Was there a stroke of genius involved? Is that treatise expected to be put to use practically, or is it an effort at obstructionism?
Sorry, I promised myself I would play with other threads.
FX-1 uses your 1:10 ratio: .5 and 5. Beutlers uses a 1:5 ratio:
Originally Posted by jdef
1 and 5. But other factors influence the amount used; ph
buffering and some thought for longevity are two.
I put a Pan F+ 120 roll through 500ml of developer which
had .3, .9, .9 gram metol, sulfite, carbonate. The solution
was slightly yellow after 12 minutes and the negatives a bit
contrasty. That, BTW, was a little Ansco 120/Beer's A.
Your A bath is a five fold FX-1 or a short sulfite D23 used
dilute. At that high ph the ascorbate, I think, a VERY
active reducer. In situ regeneration of the metol
takes place at a quick pace. Dan
Sorry about being so late with this opinion - ethylene glycol is not "very" toxic. It is probably best to say that ethylene glycol has low acute toxicity via oral, inhalation, or dermal exposure.
Originally Posted by Photo Engineer
From the first MSDS that came up online, the Oral Human Low Leathal Dose is listed as (ORL-HMN LDLO) 786 mg/kg. For a 80 kg person, that's about 62 grams of ethylene glycol.
It is even added to some wines and a study found a maximum reported concentration (6.25 mg/litre) of ethylene glycol in wine in Italy (Gaetano & Matta, 1987).
I do agree about the warning on accidental poisoning issues with children and pets. For photographic use, there should be no issues with it's use - at least as far as toxicity goes.
IF you are interested in further study - this reference will be very helpful:
Boy, that's the truth. (I'm an ordinary chemist that has specialized in chemical analysis outside of photography.)
Originally Posted by Ryuji
Ryuji - Could you name this book?
Originally Posted by Ryuji
It's mentioned on my web site as well, but the one by E. N. Mitchell. The book doesn't spend many pages on chemistry but it is a comprehensive book on photography for general scientific audience.
Originally Posted by Kirk Keyes
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