Archived posting to the Leica Users Group, 2002/01/05
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> Date: Fri, 4 Jan 2002 21:55:19 -0500 (EST) > From: Rei Shinozuka <shino@ubspw.com> > Subject: Re: [Leica] [OT] Jobo CPE-2... > Message-ID: <200201050255.VAA06302@tigercat.nyfir.pwj.com> > References: <snip> > > on the subject of developer exhaustion, Anchell goes even further: > > Although it is true, as Kodak claims, that 100ml of _undiluted_ D-76 > is sufficient to develop 8x10 inches of fim, it may not always be > enough to develop the film to its fullest potential. The amount of > solution required to cover the film's surface should not be confused with > the amount ot developer required to fully develop a roll of film. > > For example, 100 ml of solution will cover one roll of 35mm, 36 > exposure film in a JOBO CPA-2 processor. However, to _ensure_ > full development of _all_ images on the roll at least 250 ml of > undiluted D-76 should be used, no matter what any manufacturer says > to the contrary. <snip> > - Anchell and Troop, The Film Developing Cookbook p. 31 This is clearly not true, at least in the general sense, since the volumes Jobo recommends as the minimum needed are the ones that are used when processing C41 or E6. With my 2500 series reels on an ATL-1000 those numbers are 170ml for one roll of 35mm film plus a "filler" to fill up the bottom of the tank, 250ml for two rolls in a 4218 (the smaller one) tank. But interestingly, the number is only 160ml for anywhere from 1-6 sheets of 4x5 in a 4218 tank. (Yes, one sheet requires the same volume as 6 sheets). Of course, 6 sheets of 4x5 equals one and a half sheets of 8x10. Also, the amount of solution needed for either 3 or 4 rolls of 35mm is the same -- 500ml -- and only 600ml is needed for 5 rolls (in the larger 4219 tank). FWIW, the bottles in the ATL-1000 hold a maximum of 750ml. So, to have a workable strategy for using dilute B&W developers, one needs to take the Jobo minimums into account along with the tank (or motor) maximum, along with the developer manufacturer's recommendations. (The numbers listed above apply to the ATL-1000 and probably to the newer ATL-1500 as well, but other Jobo processors will undoubtedly have their own requirements.) On the subject of Xtol, it is interesting that Kodak used to publish times for 1:2 and 1:3 dilutions but has removed that information from its web site. Here is what the company has to say on the matter: - ------------------------------------------------------------------- Note:Kodak has tested XTOL Developer for long-term keeping by using typical equipment and procedures. Results indicate that mixed XTOL Developer stored for one year at room temperature (70°F [21°C]) in a full tightly closed bottle provides satisfactory results with Kodak black-and-white films when used at full strength. Some customers, however, have reported problems with developer stored for periods between six months and one year. Most often the problems related to loss of developer activity when customers were using a 1:3 or 1:2 dilution of the developer to process KODAK T-MAX 100 Professional Film. To help ensure best results, we have changed our recommended shelf life and dilutions for XTOL Developer. The new recommendations are the same as those for KODAK Developer D-76 (full strength and 1:1). The change in recommendations does not indicate any change in the formulation of the developer. If you have been consistently obtaining satisfactory results with diluted developer and you use the mixed developer before keeping characteristics can become a concern, you may want to continue your current procedures. However, Kodak publications will no longer include development recommendations for the 1:2 and 1:3 dilutions of the developer. - ------------------------------------------------------------------- To me, it is clear that Kodak is now recommending against Xtol dilutions greater than 1:1 or, at a minimum, says you do so at your own risk. - -- Rolfe Tessem rolfe@ldp.com NYC - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html