Tmax film developer question

[ronbudway]

I am using tmax professional film developer in the 1:4 ratio (mix the entire bottle with water to make one

gallon). The kodak literature states that 48 rolls can be developled, and tells you what to do to the

developing time after so many rolls, but all the info is based on 36 exposure rolls. Can anyone tell me the

numbers if you are always using 24 exposure rolls? can I just increase the totals by a third?

 

Sorry if this is a question that has been asked before, I couldn't find an answer with the photo.net search

engine. Thanks.

[frank.schifano]

See page 9 of this document for the answer:

 

http://www.kodak.com/global/en/professional/support/techPubs/j86/j86.pdf

[frank.schifano]

Yeah, so after I read your question a little more carefully, here goes. Each 36 exposure roll is approximately 80 square inches of film. Sixteen 36 exposure rolls equals about 1280 square inches. Do a little more arithmetic and you can figure that each frame is about 2.2 square inches of film. Multiply 2.2 x 24 to get the number of square inches of film in a 24 exposure load - about 53. The numbers are not exact, but close enough for what we're trying to accomplish here.

 

If you normalize the development time adjustment figures on the area of film developed this becomes really easy. Divide 1280 by 53 and you get 24.2 as the number of 24 exposure rolls equal in area to 16 x 36 exposure rolls. Then refer to the document I linked to earlier and you can figure out the rest.

[ronbudway]

Thank you so much Frank. The document you linked is where I originally found the info for

36 exposures. I knew I could do the math if I didn't get any responses. Thanks for doing it for

me.

[stephen hazelton]

Consider too, whether you want to try to mix up the whole batch, replenish, etc. (assumes you are constantly doing a bunch of film) or just mix and develop for one or two rolls at a time. Just because the container makes a gallon doesn't mean you have to mix the whole thing up at once.

[ronbudway]

Stephen, I just started teaching photography at a large high school. I'll be developing about

40 rolls a week. I just set up a system today where the kids will make a tally mark in a

designated spot every time they develop a roll of film so they know when to add a minute

and when to mix up new developer. With the previous teacher's system, they were only

getting about 14 rolls from each gallon before dumping it. This will add up to a nice little

savings for the year.

[frank.schifano]

You might want to consider running TMaxRS, XTOL, or D76, with its appropriate replenisher, in a replenished system. That might work out to be even more economical in the long run, with no need for timing adjustments. How much film do you expect to be running through the system? This time I'll let you do the math.

[ronbudway]

I can't really consider any alternatives becuase I've already received a year's supply of Tmax

developer. But because I figured out I can use a whole lot less of it than the previous teacher

was using, it'll probably end up being 2 or 3 years worth.