Archived posting to the Leica Users Group, 2007/07/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Peter, Try this. http://www.digitaltruth.com/devchart.html I find the information is this chart is very good. It pretty much covers every film with every developer made. Len On Jul 25, 2007, at 5:08 PM, pmcc wrote: > Many thanks Marty. Your posting was interesting and > helpful even to a non-chemical DIY'er such as myself. > You've inspired me to get out the hazmat gear, roll > down my sleeves and go to work. > > Next question: can you point to or have you derived > dev'pt times for Xtol at various dilutions -- 1:2 and > most particularly l:3 -- for various common films? > Higher dilutions don't appear on the product data > sheet. I've seen frequent discussions of the manifold > benefits of higher dilution, and it would be great to > have specifics for starting points. > > Peter. > SF, CA > > P.S. Hey, this is a non-digital thread -- feels like > Y2K. > > >> Since there is a bit of interest in chemical >> developers after the LuG being almost completely >> digital, I thought I'd post this. I wrote it for a >> newsletter a few of us here in Adelaide write and >> send around to each other. A lot of this is based >> on discussions I've had with LuGer John Black. The >> formula for JB9 is entirely his - and it's elegent >> and effective. My own experiments in pH were >> initiated after discussions with him and follow an >> approach I developed from our discussions. >> >> What follows is a long rant about Kodak Xtol. >> >> Xtol is probably the best commercially available >> developer for 35mm film. Why is it so good? It is >> an ascorbate developer. Ascorbates are effective >> developers of silver? with about the same >> efficacy at developing as hydroquinone, but the >> development by-products of ascorbates are acidic and >> act as development inhibitors. These by-products >> inhibit development proportionally to exposure (i.e. >> they inhibit more in dense areas of the negative and >> less in thinner areas). All ascorbate developers >> are, therefore, compensating developers with high >> acutance, dependant to some extent on the other >> components of the developer. This is good for >> tonality. ?Compensation? is claimed for >> many developers, but the ascorbate ones are among >> only a few where it has any real scientific basis or >> measureable effect. Kodak?s chemists were >> clever with Xtol in several ways beyond using an >> ascorbate as the primary developing agent. They >> added enough sulfite that the stock! >> solution can be used as a grain-reducing developer >> and as a replenishment developer where the only >> replenisher needed is more Xtol. This sulfite >> concentration, combined with high activity, allows >> the developer to be used at dilutions of up to 1+1, >> 1+3 or 1+5 depending on the film being developed. >> This results in enhanced edge effects; it maximises >> direct development and minimises solution or >> physical development (called ?solvent >> action?), increasing sharpness. They also >> used dimezone-S as the superadditive co-developer. >> Dimezone-S is a potent developer at low >> concentrations (it is, after all, similar to >> phenidone) but is easier to dissolve in water than >> phenidone and is less likely to oxidise once in >> solution. Properly mixed Xtol is actually quite >> stable ? not Rodinal or PMK Pyro stock stable, >> but very good. >> >> So it?s sharp and has great tonality. Super. >> Unfortunately, Xtol got a reputation early on for >> both failing catastrophically and leaving odd >> artefacts in negatives. So, what gives? Is it >> great or does it suck? >> >> As usual, the answer to both is yes. Xtol fails for >> two reasons. Ascorbates are strong antioxidants and >> will scavenge oxygen from solution. Unfortunately >> the oxidation products of ascorbates do not develop >> latent silver images and do not present a colour >> change in solution. This explains what we already >> know ? Xtol can die without warning. The other >> reason Xtol can fail is that the oxidation of >> ascorbates is catalysed by metal ions in water >> ? particularly divalent cations (they are the >> 2+ ones). These include calcium and iron, the >> former common in ?photo grade? chemicals >> and the latter common in tapwater. Odd donut-shaped >> dots on negatives developed in Xtol are seen >> sometimes even by people who are careful about air >> and mixing. I suspect this occurs when impure >> dilution water is used and a little particle of iron >> or some other substance ends up onthe film, >> oxidising the ascorbate (and therefore inhibiting >> development) forsome distance around. I! >> t?s not likely tobe in the original mix >> water, since impurities here would probably kill the >> developer, unless it was mixed and then used almost >> right away. >> >> ?Sudden Xtol death syndrome? can be >> fixed by keeping bottles completely full and in the >> dark; ?Xtol spots? can be avoided by >> always using distilled or deionised and filtered >> water to mix and dilute Xtol. Whether you think >> that is worth the bother is up to you. I think it >> is. >> >> Can you mix your own Xtol? Sort-of. Mark Rabiner >> sent aroundthe basic formula from the patent >> (that?s not an MSDS ? an MSDS is the >> ?material safety data sheet? and the one >> for Xtol can be accessed by going here: >> > http://www.kodak.com/eknec/PageQuerier.jhtml?pq- > path=2879/4648&CID=go&idhbx=msds&pq-locale=en_US&_requestid=2627 >> and typing Xtol in the product name box) which comes >> from the patent. There are, however, indications >> from the physical behaviour of Xtol that what Kodak >> sells is somewhat different. Xtol stock solutions >> have a pH of 8.2 (what Kodak says); diluted to 1+3 >> the pH rises to 8.3-8.4. If you make the patent >> version, the startings olution is 8.35-8.4 and it >> stays fairly stable with dilution. Those pH >> differences might not seem like alot, but >> they?re important. The version from the >> patent is also about 30% less active. What does this >> tell us? The?weakly alkaline? >> (Kodak?s terminology) pH must come from a >> buffe! >> r, rather than just from metaborate and >> metabisulfite. I suspect a small amount of boric >> acid (i.e. a metaborate-boric acidbuffer) ? it >> makes the most sense chemically; I also have some >> supporting data frommass spectroscopy analysis of >> commercial Xtol. The EDTA is also probably not >> enough on its own to sequester the divalent cation >> concentrations that Xtol can handle ? I did >> this by adding known concentrations of dilute cation >> solutions to Xtol and self-made analogues and >> comparing them. >> >> So, what can you really do? Buy Xtol, of course. >> But if you really want to make a substitute, the >> following are options: >> >> Patrick Gainer?s PC-TEA >> 9 grams ascorbic acid >> .25 grams phenidone >> 100ml triethanolamine (TEA) >> Heat the TEA in a pyrex container in themicrowave >> for 30 sec.-1 minute, and add the ascorbic acid. >> When it isdissolved, add the phenidone. Be careful, >> because the TEA will get VERY hot. >> >> Dilute the concentrate 1:50 for use. >> >> PC-TEA is very good and if you have access to cheap >> TEA as those in the US do through >> www.chemistrystore.com it costs hardly anything. >> It?s grainier than Xtol, however, and >> doesn?t change its characteristics when >> diluted more. It works because it is very alkaline, >> which I think contributes to the grain >> characteristics of films developed in it. Many >> other ascorbate formulae have these flaws ? >> the absence of the weakly alkaline pH, low sulfite >> concentration (but withsome sulfite still present) >> and the increase in activity with dilution are what >> make Xtol extraordinary. >> >> John Black?s JB9 is functionally the same as >> Xtol, but you mix it yourself. >> >> The developer is made from 3 liquid concentrates >> that are stable for at least 6 months, perhaps a >> year (stability testing underway). Store the >> solutions in glass bottles, tightly capped. The >> solution A should be store in the dark (a closed >> cabinet is fine) or in an amber bottle. >> >> Solution A: (Phenidone, ascorbic acid) >> >> Phenidone 1.25 gm >> Ascorbicacid- 50.00 gm >> Ethyelene or >> propylene glycol >> or dry methanol- 600 ml >> >> Warm up solvent to hot tap water temp before >> dissolvingcomponents. They will dissolve at about >> 100-125F. Dissolve ascorbic acid first. >> >> Solution B: TBE (Tris-borate-EDTA) Sigma cat# T3913 >> One 1L dry pkg dissolved in 1L DI water >> Other buffer concentrates may be substituted if made >> up to about half molar at a pH of about 8.3. Boric >> acid-metaborate(BA/Kodalk) would be fine, you may >> have to fiddle a bit to get the right pH. >> >> Solution C: Saturated Na Sulfite solution >> Na Sulfite(anhydrous)- 180 gm >> Distilled water- 600 ml >> >> Stir vigorously for about 30 min. Temp will rise a >> bit and it will almost all go into solution. Let >> stand overnight to equilibrate (some will >> crystallize out). Use after that. >> >> JB9 developer: >> SolA: 10 ml >> SolB: 50 ml >> Sol C: 20 ml >> Distilled H2O Fill to 250 ml >> >> Add sol B and C to water first, mix and then A >> (protects phenidonefrom oxygen in water). This is >> enough todevelop 1 roll of 35mm film. Scale up as >> necessary. Works best as a 1 shot developer at 68F, >> with moderate agitation. I use 13 min for Tri-X. >> >> I?ve used the tris and metaborate/boric acid >> versions of JB9 and they are functionally identical >> to Xtol. You can modify the sulfite concentration as >> you like. One of the best things about JB9 from my >> perspective is that you can mix the developing >> agents to the same concentration as Xtol stock, but >> keep the same sulfite as Xtol 1+3 (or any other >> favoured dilution). This is great for films like >> TMX and Acros that run out of developer in Xtol 1+3, >> or for pushing TMZ. >> >> Of course the other option is to mix the patent >> formula Xtol and addboric acid until the pH of the >> stock is 8.2, but you may also run into problems >> with 'photo grade' chemicals. I really don't think >> the EDTA alone is enough to chelate ions out of the >> chemicals or water. >> >> Also look at US patents # s 3658527, 5376510, >> 5503965, 5738979, 6110655, 6489090, 6673528 and >> 6686135 in addition to the Xtol patent 5756271. >> >> I hope this explains a few things and is >> interesting. >> >> Marty >> >> >> -- >> We've Got Your Name at http://www.mail.com! >> Get a FREE E-mail Account Today - Choose From 100+ >> Domains >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for >> more information >> > > > > > ______________________________________________________________________ > ______________ > Pinpoint customers who are looking for what you sell. > http://searchmarketing.yahoo.com/ > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information