Someone just gave me a big Patterson tube/tank for processing 1/220 film. It holds 5 rolls, and even more for 35mm. Will my times, chemical quanities, etc., be the same for it (i.e., times the same, liquids = x 5)? More importantly, can I expect the middle rolls to develop the same as the end rolls? I agitate quite vigourously, and in the 'eyes' of the film, quite sporadically...

...don't want to use it tillget some "it's OK"s...shawn

-- shawn gibson (SeeInsideForever@yahoo.com), March 12, 2000

Answers

It's OK.

Well, in any case ...

... you may have to test it. I always remember what Ilford say in their film fact sheets: The times indicated are given for guidance, and may vary considerably depending on your specific way of doing it.

Consider this:

1) It will take longer to pour the chemistry into the tank. But it will also take longer to pour it out again. That means that development starts earlier at the bottom roll, but also ends earlier at that roll. So if you are lucky, the two effects cancel. They will, at any rate, not be very significant when the development time is long anyway. While with my small tank, I dare to use 5 minutes as the minimum development time, I would hesitate to do that with a big tank.

2) Using the large volume has the advantage of greater consistency. When you prepare a large volume of chemistry, the relative error in preparing the working solutions is usually less than that for a small volume. For example: If you have an absolute measuring uncertainty of 0,1 ml for the concentrated chemcial (the actual value depends on your equipment and your way of handling it), this will give you a relative uncertainty of 1% in 10 ml, 0,1% in 100 ml, etc.

3) I wonder if you will in fact agitate such a big tank vigourously. For two rolls of 35 mm, 500 ml of chemistry are common. That would make 2,5 litres for 10 rolls. It would certainly make a good exercise to wiggle abouta little more than 2,5 kilograms. If you observe that your agitation gets slowed down by the big mass involved, expect the result of the development to change. However, I wonder if the effect is big. Actually, agitation aims at bringing fresh developer to the heavily exposed places. In other words: by agitating, the developer is mixed again to have a uniform concentration everywhere. When you use one-minute agitation, I think the four inversions in 10 seconds suffice to have the developer mixed again to equilibrium. Therefore, as long as you stick with the four inversions in 10 seconds, there should not be too much of a difference.

-- Thomas Wollstein (thomas_wollstein@web.de), March 13, 2000.

Thanks Thomas, some really good advice. I think maybe I should grab some expired Tri-X or something and test on unimportant stuff first. All the things you said make sense, glad I asked...shawn

-- shawn gibson (SeeInsideForever@yahoo.com), March 13, 2000.

Shawn, it would kind of scare me; I would definitely do my own testing with it first. Here are my main concerns (also, I'm only addressing B&W):

1) As Thomas pointed out, fill times would be longer. I think the major problem here is splashing onto the top rolls while the bottom rolls are being submerged (for both developer and stop/fix). This is probably relatively insignificant if the tank fills and empties rapidly, OR if development times were substantially long.

2) I know I can knock airbells off the film with my normal setup (a single or double 120 reel Nikor tank) by rapping with my knuckles. I question whether I could do that with a 5-reel 120 tank; I would want to experiment with how hard to rap.

3) Regarding evenness of development, I assume (presume?) the tank gets inverted? If so, keeping a large air bubble (ie, leave some airspace when you fill the tank) is probably important. As you invert the tank, this bubble traveling up through the reels greatly assists in random agitation. If you're really concerned about evenness, you really need to test with some evenly exposed frames; density readings are the preferable way to evaluate.

-- Bill C (bcarriel@cpicorp.com), March 13, 2000.

I use Paterson tanks, usually small 2 or 3 roll tanks, sometimes 8. I use the same time/temperatures whatever the number. True, I haven't used a densitometer on the films, but any difference must be very slight.

The 8-tank is rather a beast, and I wouldn't recommend it for the faint-hearted.

-- Alan Gibson (Alan@snibgo.com), March 15, 2000.