Thank you for sharing.Found this on archive.org and thought I'd share it. Has a lot of general information, but contains some formulas and other info on Edwal developers and other chemistry: https://ia800202.us.archive.org/7/items/ModernDevelopingMethods/Edwal - Modern developing methods (1947).pdf
3rd Edition, Sixth printhing: March 1947
Thanks!!
Interesting read ... the Edwal 10 formula listed is quite different than the one I found on Photrio.
Thanks. I note from p129 that Diamine-P is p-phenylenediamine and Monazol is glycin.
I hope to make some Edwal 12 (p30) sometime to compare with Jay DeFehr's Halcyon I made and used up.
Found this on archive.org and thought I'd share it. Has a lot of general information, but contains some formulas and other info on Edwal developers and other chemistry: https://ia800202.us.archive.org/7/items/ModernDevelopingMethods/Edwal - Modern developing methods (1947).pdf
3rd Edition, Sixth printhing: March 1947
This is a nice book with a lot of useful information. On page 32 it has a picture of a chapel which according to the book "was made by Dr. E. W. Lowe in 1932 from a negative on the first full roll of film ever developed in Edwal-12". Does this mean that Dr. Lowe didn't develop full rolls of film with intermediate versions of his developer?
Has anyone attempted Edwal 20.
There's some uncertainty about the composition of a key ingredient, Gradol.
Gerry Koch seemed pretty sure the last time @Paul Howell asked about ithttps://www.photrio.com/forum/threads/edwal-20-and-gardol-is-it-pyro.140425/
So, can it be used just like Gardol, in terms of same amount of p-aminophenol for Gardol or it does it need to be further refined to become Gardol?
Very cool!I have my Dad's copy, pre-war I believe.
I found my Dad's copy, 3rd edition April 1945. My Mother gave it to my Dad January of 1946, this was their 2nd anniversary. They got married off the Navy base he was assigned right before going to support the big push in the Pacific Theater WWII.In that other thread Gerald Koch suggested calculating the molecular weights and adjusting accordingly: "You can substitute the hydrochloride salt if the make adjustment for the differing molecular weight." I can't find the hemisulfate he describes but it looks like p-aminophenol sulfate has a molecular weight of 207.21 g/mol. vs p-aminophenol hydrochloride is 145.59 g/mol .
If he's right about the substitution, and he meant sulfate, then you'd use 70% as much p-aminophenol hydrochloride, so 3.5g p-aminophenol hydrochloride according to the formula you posted. Hopefully someone like @Alan Johnson can tell me if I'm off about either of those things.
Very cool!
In that other thread Gerald Koch suggested calculating the molecular weights and adjusting accordingly: "You can substitute the hydrochloride salt if the make adjustment for the differing molecular weight." I can't find the hemisulfate he describes but it looks like p-aminophenol sulfate has a molecular weight of 207.21 g/mol. vs p-aminophenol hydrochloride is 145.59 g/mol .
If he's right about the substitution, and he meant sulfate, then you'd use 70% as much p-aminophenol hydrochloride, so 3.5g p-aminophenol hydrochloride according to the formula you posted. Hopefully someone like @Alan Johnson can tell me if I'm off about either of those things.
Very cool!
https://archive.org/details/whatyouwanttokno00lowe/page/32/mode/1up?view=theater
Edmund Lowe said Gradol is a derivative of p-aminophenol so it seems likely that Gerald Koch was right.
I might order p-aminophenol, I have the other chem stashed and mix a liter to see how well it works. Saying that, gain is so much finer with modern films than GAF 500 I'm not sure what the value will be. Foma 400 at 200 or 100, might be worth a try.
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