Six changes of 1 litre will dilute the first, say 1ml left on the film and reel, more than 1:10^6 times. In other words there will be less than a millionth or a ten millionth if you rinse the reel before starting the wash, of the original fixer solution left assuming that only 1 ml stays behind on the reel and film each time. But this does not account for the fixer that was bound to the emulsion. That removes itself by diffusion and takes about a minute (I think) and agitation prevents it diffusing back. I would say that ten changes of a litre every minute would be perfect, and it's what I do, and have half an hour ago just done.
The preliminary rinse before starting the washing cycle is a good idea. I wash B&W the same way I do negative colour. One drop of fairy liquid in the last bath helps too. The reel is agitated continuously while it's in the wash water. Don _______________ Dr E D F Williams http://personal.inet.fi/cool/don.williams Author's Web Site and Photo Gallery See Extra Pages 'The Cement Company from HELL!' Updated: August 15, 2003 ----- Original Message ----- From: "graywolf" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, March 30, 2004 6:53 AM Subject: Re: Recommendations: Roll Film Washer > 6 changes are supposed to reduce chemicals in film or RC paper about 1000:1. > It's boring though, as you know. The hose through the reel into the bottom of > the tank takes about 15-20 minutes to reach the same level, but uses a lot more > water as Bill says. > > Most efficient. One rinse. Hypo clear. 2 more rinses. That that only save you > two changes of water, but might be worthwhile if you have to haul water in. > > -- > > Bill Sawyer wrote: > > > Bill, > > > > Thanks for the insight. What you describe is what I have been doing. Fill & > > dump, fill & dump. I thought there might be a more efficient method. Maybe > > not, huh. > > > > Sure is tough to get a straight answer around here lately, though. > > > > -----Original Message----- > > From: William Robb [mailto:[EMAIL PROTECTED] > > Sent: March 29, 2004 6:28 PM > > To: [EMAIL PROTECTED] > > Subject: Re: Recommendations: Roll Film Washer > > > > > > ----- Original Message ----- > > From: "graywolf" > > Subject: Re: Recommendations: Roll Film Washer > > > > > > > >>No, no, no! You must, absolutely must, buy a $500 "ARCHIVAL" film > > > > washer. > > > > > > The intersting thing about film washing is how easy and quick it > > really can be, with no additional equipment. > > > > A hose running a slow trickle of water into a tank will probably take > > a half hour to wash the film, and speeding up the water flow won't > > change that time significantly. > > You will also run 80-120 liters of water, perhaps more. > > This is how most archival washers work, the big difference between it > > and running a hose ito the processing tank is that in theory (though > > not necessarily in practice) the archival washer works more > > efficiently. > > > > OTOH, if one remembers that the soak through time on film emulsion is > > around 15 seconds, and that double that effectively removes all the > > chemistry that is going to be removed by that tankload of wash, then > > all you need to do for archival washing is a fill and dump regimen > > where you fill the tank with clear water and gently agitate it for a > > half minute, drain and repeat a half dozen times. > > > > You can archivally wash a tank of film in less than ten minutes this > > way, and are using far less water (which is too valuable to waste) > > than a running water bath. > > > > In the Jobo, I can archivally wash a dozen rolls of film in less than > > 10 liters of water. > > > > William Robb > > > > > > > > > > > > -- > graywolf > http://graywolfphoto.com/graywolf.html > > > >
