It simply takes a liter to get deep enough to sink the rack completely.

I do try to save up film for a processing day when I can make a liter and do 4 sheets and some 120 and some 35mm with the same liter.

Quote Originally Posted by Anon Ymous View Post
Mark, the chemicals needed (as in chemical reactions) for any format are proportional to the surface of the film. In your case, 4 4x5 sheets should need the same amount of chemicals as a 135, 36exp film. Obviously, it doesn't take into account any differences about the needed volume to cover the reels. The critical detail in this case is how much you can reuse the chemicals. Whenever you agitate, you put air in the solution, which inevitably decreases their useful life. That might be an assumption from my part, but I can't think of anything else.