Tmax & D-76
in [Darkroom]
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From: Richard Knoppow on 6 Aug 2010 02:20 "Jean-David Beyer" <jeandavid8(a)verizon.net> wrote in message news:i3f34u0b89(a)news3.newsguy.com... > Richard Knoppow wrote: > >> Being big is not always an advantage. Years ago I came >> across a very >> interesting paper called "On Being the Right Size". I >> can't remember >> the author, it was in an anthology of papers on either >> mathematics or >> physics published by _Scientific American_ magazine. >> Maybe a web >> search would find it. >> > It can be found in The World of Mathematics, Volume 2, > pages 952 ff. > "On Being the Right Size" by J.B.S. Haldane. Haldane, J. > B. S. (March > 1926). "On Being the Right Size". Harper's Magazine. > > > -- > .~. Jean-David Beyer Registered Linux User > 85642. > /V\ PGP-Key: 9A2FC99A Registered Machine > 241939. > /( )\ Shrewsbury, New Jersey http://counter.li.org > ^^-^^ 15:10:01 up 11 days, 18:02, 3 users, load average: > 5.12, 4.86, 4.80 That's it! Thanks, I thought it was in that series. -- Richard Knoppow Los Angeles, CA, USA dickburk(a)ix.netcom.com
From: Digitaltruth on 6 Aug 2010 12:33 MSDS are designed for health and safety, so although they can provide very useful information about specific formulas, my understanding is that there is no requirement to list any chemical that constitutes less than 5% of the total volume (unless, I presume, it would be hazardous in such a concentration). While the current MSD sheets for Perceptol and Microdol-X do list the same composition, there is no way to know what other chemicals under 5% are included. Older MSD sheets for Microdol-X list Boric Anhydride and Sodium Hexametaphosphate in concentrations of less than 1%, and as Richard points out, there may be multiple different historic MSDS out there listing other ingredients. In the Film Developing Cookbook (1st edition, 1998) Bill Troop states that the exact formula for Microdol-X is proprietary and unpublished. While the general formula for the original Microdol is now common knowledge, Troop points out that its successor, Microdol-X, differs from this earlier formula as it contains an anti-silvering agent, which he suggests is probably a benzophenone anti-staining agent. In speaking to Bill about this difference a few years ago, the understanding I came away with was that the anti-staining agent contained in Microdol-X is not incorporated in Perceptol, and this is the key difference between the products. Troop says in his book that the formulas are "chemically close." Perhaps they are close enough for development times to be the same, but I would want to have more information from experienced users who have done side-by-side testing.
From: Richard Knoppow on 6 Aug 2010 15:11 "Digitaltruth" <info(a)digitaltruth.com> wrote in message news:29dc66a7-23f8-4e08-b3d1-8b10f5595b2c(a)t2g2000yqe.googlegroups.com... > MSDS are designed for health and safety, so although they > can provide > very useful information about specific formulas, my > understanding is > that there is no requirement to list any chemical that > constitutes > less than 5% of the total volume (unless, I presume, it > would be > hazardous in such a concentration). > > While the current MSD sheets for Perceptol and Microdol-X > do list the > same composition, there is no way to know what other > chemicals under > 5% are included. Older MSD sheets for Microdol-X list > Boric Anhydride > and Sodium Hexametaphosphate in concentrations of less > than 1%, and as > Richard points out, there may be multiple different > historic MSDS out > there listing other ingredients. > > In the Film Developing Cookbook (1st edition, 1998) Bill > Troop states > that the exact formula for Microdol-X is proprietary and > unpublished. > While the general formula for the original Microdol is now > common > knowledge, Troop points out that its successor, > Microdol-X, differs > from this earlier formula as it contains an > anti-silvering agent, > which he suggests is probably a benzophenone anti-staining > agent. > > In speaking to Bill about this difference a few years ago, > the > understanding I came away with was that the anti-staining > agent > contained in Microdol-X is not incorporated in Perceptol, > and this is > the key difference between the products. Troop says in his > book that > the formulas are "chemically close." Perhaps they are > close enough for > development times to be the same, but I would want to have > more > information from experienced users who have done > side-by-side testing. The problem is how does Bill Troop know what is in Perceptol? I have used it exetensively with T-Max and have never seen a hint of dichroic fog. Kodak has a bunch of patents on anti-silvering agents, which it also calls anti-fog agents in some places. Such agents are used in many places including emulsions. Who knows which, if any, were used in Microdol-X. Note that the former Kodak extra-fine-grain developer DK-20 employed a silver solvent namely thiocyanate. It became useless for modern films because of the serious dichroic fog it produced. BTW, I think I may have referred to D-20 in an earlier part of this thead, I meant D-23. Bad memory. -- Richard Knoppow Los Angeles, CA, USA dickburk(a)ix.netcom.com
From: Richard Knoppow on 7 Aug 2010 03:15
"Keith Tapscott." <Keith.Tapscott..6a23329(a)photobanter.com> wrote in message news:Keith.Tapscott..6a23329(a)photobanter.com... > > Richard Knoppow;886179 Wrote: >> >> Kodak is reportedly discontinuing D-76, Microdol-X, and >> Kodak Hypo Clearing Agent. >> -- >> Richard Knoppow >> Los Angeles, CA, USA >> dickburk(a)ix.netcom.comI am aware that Kodak have >> discontinued Microdol-X, D-76R replenisher > and the larger packaged sizes of D-76, but I have not read > about the > regular hobby sizes of D-76 being discontinued. > Where did you read about Kodak D-76 being discontinued > altogether? > > > > > -- > Keith Tapscott. Someone posted it to a news group or it may have been the Pure-Silver mailing list. I wondered at the time if it was accurate. I found nothing on the Kodak web site. I hope its not true. I also don't understand why they would discontinue KHCA which should have a continuing sale. OTOH, Kodak is a giant mega corporation and their management often seems not to make sense to me. -- Richard Knoppow Los Angeles, CA, USA dickburk(a)ix.netcom.com |