BOB KISS wrote: > DEAR RICHARD, > Please give us your take on this: I know that pin holes occur from > the interaction of a carbonate (e.g. sodium) with acid, like the acetic acid > stop bath, but I also thought that this we very temperature dependent. When > using a developer-stop bath process, I have always processed at 68-70 F and > have never experienced pin holes with the 8 different films I have used over > the years. I mostly use PMK with a water rinse and this is a non issue with > this dev but there are times I want the effect of other devs. > I recall a student who said that I was being compulsive to insist > that he process at 68-70 F using D-76 and stop bath. He said he didn't want > to spend the time and money keeping his darkroom cool and cooling the solns > before processing. I process my films (35mm and 4x5) in a Jobo CPE-2 processor. I have a Lawler pressure-temperature regulating mixing valve that will go as hot as I want, but will not go down quite to the cold water supply temperature. So I calibrated all my processing at 75F. This handles most of the year. In the hottest days of summer, I put one of those frozen ice packs in the water jacket and wait until the water jacket is down to 75F. I then remove the ice pack. If I am processing only one tank of film, that is enough. If I need to do more tanks, I may put the ice pack back in the water jacket to ensure the developer remains at 75F. I do not air condition the darkroom anymore because the a/c quit and it is too complicated to replace it. The chemistry bottles sit in the water jacket. I measure the temperature by keeping my Kodak Process Thermometer (the stainless steel mercury one) in the developer bottle and take what I get in the others. I wash everything in the temperature of what comes out of the mixing valve, which is 75F most of the year and can get up to 80F or so on bad days. This works fine for TMax type films that are all I use these days. No pinholes. I do use SB-5 stop bath and Xtol developer 1+1. I do not know what is in that, but sodium carbonate is very unlikely to be one of the ingredients. > He insisted that he could just adjust the dev times and > process at 80 F or higher. Well, his rolls of 120 negs looked like they had > been shot with birdshot...so many tiny clear holes, they were all ruined. A > rather expensive lesson he will never forget. > CHEERS! > BOB -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 12:15:01 up 18 days, 5:52, 3 users, load average: 4.75, 4.94, 4.88 ============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.