Archived posting to the Leica Users Group, 2002/03/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I would suggest the potential "pin hole" problem caused by carbonate and acid stop bath combination may exit with more than Rodinal. T.E.C. and Neofin Blue are similar to the Will Beutler formula for thin-emulsion film processing and they contain substantial amounts of carbonate. - ----- Original Message ----- From: "Jim Brick" <jim@brick.org> To: <leica-users@mejac.palo-alto.ca.us>; <leica-users@mejac.palo-alto.ca.us> Sent: Monday, March 25, 2002 5:12 PM Subject: [Leica] Re: Re: Darkroom Question > Mark, > > What you are speaking of is air bells. Pin holes are different, as I > explained in my post, AND I explained that they are virtually impossible to > get with today's developers. > > But stop bath CAN cause pin holes, the only source of pin holes, the plague > of the 30's, 40's, and 50's since some over the counter standard developers > had carbonate in them. Carbonate in a developer plus an acetic acid stop > bath can indeed, and did, cause "pin holes." Eruptions of gas from within > the emulsion. The possibility still exists, albeit remotely, with Rodinal. > > Jim > > > At 10:36 AM 3/25/2002 -0800, Mark Cohen wrote: > > >I don't think that stop bath can cause pinholes.. If anything, if the stop > >acetic acid was full strength, the film would melt. > > > >The leading cause that I've heard of is not tapping the tank after you > >pour in the developer. Air bubbles can stick to film and prevent developer > >from working on that area.. Then when the film is fixed, the non-developed > >"holes" are fixed away and you're left with little clear holes in the > >emulsion. > > > >-Mark > > > > > > > >On Mon, 25 Mar 2002, Jim Brick wrote: > > > > > At 09:04 AM 3/25/2002 -0600, Bill Satterfield wrote: > > > >Was in the darkroom over the weekend developing film. I use a tank. On > > > >one batch, I used a ounce of short stop to 15 1/2 ounces of water rather > > > >than a 1/2 ounce. Film looks OK. What harm did I do and what can I > > > >expect?. A mental error caused by waiting to long to develop rolls of > > > >film. Perhaps, I ought to develop more frequently. Thanks > > > > > > > > > Actually, no harm. I have never used a stop bath in film processing in my > > > 50 years of darkroom work. It is unnecessary. But too much stop won't > > > bother anything anyway unless you are using a developer containing > > > carbonate. Which there are none of nowadays. > > > > > > Hydroxide will evolve CO2 but Rodinal is about the only normal contrast > > > developer containing it. But I have never known anyone to have stop bath > > > problems, regardless of concentration. > > > > > > When I started darkroom work in the 50's, there were carbonate containing > > > developers being used and stop bath had the possibility of causing "pin > > > holes" which is gas forming within the emulsion, rapidly being released, > > > causing an eruption thus a pin hole. Because of this, I was taught (Brooks > > > Institute of Photography) to simply use water as a rinse between the > > > developer and fix with film. It has served me well for all of these years. > > > > > > Jim > > > > > > -- > > > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > > > > > > >-- > >To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html