hans_beckert Posted February 17, 2004 Share Posted February 17, 2004 The PH of Microphen is too high, resulting in too-short developing times. I want to slow it down without diluting it. Which acid is better: Boric acid or sodium bisulphite? I do not want to lose the speed-enhancing properties. Link to comment Share on other sites More sharing options...
__jon__ Posted February 17, 2004 Share Posted February 17, 2004 Why not dilute it? Link to comment Share on other sites More sharing options...
jorge_oliveira2 Posted February 17, 2004 Share Posted February 17, 2004 What is usually believed to be Microphen uses a borax-boric acid buffer. So, boric acid would be more like it. Try 1g at a time. Link to comment Share on other sites More sharing options...
chris_waller Posted February 18, 2004 Share Posted February 18, 2004 I'd agree with Jorge and also suggest boric acid. Link to comment Share on other sites More sharing options...
hans_beckert Posted February 18, 2004 Author Share Posted February 18, 2004 Jon Witsell, feb 17, 2004; 09:39 p.m. "Why not dilute it?" Because that would lessen the solvent action. Link to comment Share on other sites More sharing options...
mikael1 Posted February 18, 2004 Share Posted February 18, 2004 Please post a follow-up on this if you try it, I'm also a bit interested. Link to comment Share on other sites More sharing options...
patrick_gainer Posted February 22, 2004 Share Posted February 22, 2004 While you're at it, you might try a tiny bit of ascorbic acid. Not the ascorbate, which would probably increase activity. I know, everyone thinks I am obsessed with Vitamin C in developers. Read the article "The Role of Antifreeze in Photographic Science" in Photo Techniques Mar/Apr. You'll see I play with hydroquinone, catechol, pyrogallol, and other poisons as well. Link to comment Share on other sites More sharing options...
__jon__ Posted February 22, 2004 Share Posted February 22, 2004 >Hans Beckert , feb 18, 2004; 09:41 a.m. >Because that would lessen the solvent action. Have you tried it? Link to comment Share on other sites More sharing options...
lex_jenkins Posted February 23, 2004 Share Posted February 23, 2004 I don't know whether Microphen is derived from or based on another fairly well established developer or is totally unique and proprietary. It does appear to lean on phenidone, hence the "phen" in the name. It shares many ingredients with ID-11, tho' I don't know the amounts or proportions. One of those is sodium sulfite so it's reasonable to question whether dilution would affect the solvent action. And while it's one of my favorite developers, I must admit that I haven't conducted particularly thorough research. I tried it at various dilutions with pushed film, mostly TMY, and quickly concluded that it worked best (for me) at full strength. Better effective speed enhancement, grain, contrast, etc. Link to comment Share on other sites More sharing options...
tklim Posted February 25, 2004 Share Posted February 25, 2004 Hi, everybody. I've had lots of experience with Microphen. I've also come across a number of various formulae of this time-honoured dev. It seems to me that the one closest to the original goes as follows: Sodium sulphite - 100 g Hydrquinone - 5 g Phenidone - 0.2 g Borax - 6.8 g Boric acid - 2.7 g Sodium metabisulphite - 0.65 g Potassium bromide - 1.0 g Water to make - 1000 ml Taking the above as a starting point you can experiment with the actual proportions of the bufferring substances. When unchanged, the quoted formula gives results identical with Microphen, although it takes some weighing out of chemicals. There's another PQ formula that I've used and liked a lot, it's G. Crawley's FX-18 which is said to be a phenidone version of D-76, but in my opinion it gives superior results on all types of emulsion. It's only disadvantage is that it visibly changes its activity over its shelf-life, and does it without warning. Surprisingly, the solution /unused/ becomes more active during the storage time in a degree very difficult to compensate for. On the other hand, its the ONLY B&W film dev that yielded all I - IX zones densities lying on a straight line (!) in an 'N' development process for 35 mm HP-5 rated at 320 ASA. Good luck in your experimenting. Tomasz Klimkiewicz Link to comment Share on other sites More sharing options...
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