How much solution?

I have a no name 24 inch processing drum.
I need to process some 12x20 film in it and I don't know how much solution to use. How do I determine the correct amount of total fluid to use to process the film so I get good coverage?

Thanks
Gary

24 May 2008

Gary892:

First off, I assume that you are intending to "rotary process" this film.

There is an analytical way to calculate the amount of solution that you will need, but it is best explained with a diagram. If you PM me I will scan and send you the diagram and associated formula to calculate the volume needed.

The more imperical way is to load the tank wit a given amount of water, with reels in place, cover the open end of the tank with Suran (or like) film. Use a rubber band to further insure it is watertight. Place the tank on it side and not whether the innermost position (on the reel) that film would be is covered with water. If not, you need more solution. If so, then you might be able to remove some.

Hope this helps.

Regards,
Darwin

I guess a 24" is similar in size to a Jobo 2850? IIRC that's only 200ml to cover. But that's not enough to develop a sheet of film normally. How much developer do you need for the film ?[ignore the drum for now]

24 May 2008

Gary:

Here is the scan that I mentioned in my PM to you.

A "cord" is the line marked as "c" in this diagram. The arc "s" represents the tank wall. Hope this helps and is not too confusing.

Regards,
Darwin