small vs large tanks and compensation

[WoolenMammoth]

I just ran two rolls of film in a 2 reel stainless tank. Came out perfect at 12 minutes. Switched to an 8 reel tank, same film, time and developer and the negs are the slightest bit underdeveloped in comparison. Does that make any sense? Is it normal to have to compensate for a larger tank? Its a 1:16 solution of FG-7 and trix.

 

[Roger Hicks]

Less agitation? Tank cooled more (or previous tank heated more)? Always a good idea to check dev temperature after emptying as well as before filling.

In other words, no, there are no theoretical reasons for compensation -- but B+W photography is as much alchemy as science.

Cheers,

R.

 

[WoolenMammoth]

everything was the same, hence my puzzlement.

 

[Blanco Dos]

everything was the same, hence my puzzlement.

There is no need for puzzlement or guessing. This is quite normal.

Film manufacturers advise longer development times for when using a large tank. As on this Kodak film box though they only mention times here for small tanks (I marked in yellow). For more information you could find a spec sheet for your film from the manufacturer's web site.

 

[raytoei@gmail.com]

slightly off-topic here, i know that there are differences in development time between 135 and 120 format. How about 24 vs 36 exposure ? thanks!

 

[Ronald M]

If you gave the same agitation, small and large tanks would be the same. Problem is you don`t. Any inverted agitation tank will be the same.

Large tanks are gallon size ones or larger and agitation is once per minute by remove and replace or gasious burst.

Time is the same for 1 to 8 reel tanks providing you fill and agitate the same for all. This means dropping film into a preloaded tank in the dark, not filling thru the top. A lift rod is required for 4 and 8 reel tanks.

If you do the lift rod with a gallon tank and agitate with the lift rod, it matters not if it is 4 reel, 8 reel or gallon tank. But if you use gaseous burst if dip dumk on 60 sec intervals, time will be different.

 

[Roger Hicks]

Ronald is absolutely right. The terms 'small tank and 'large tank' mislead many who are unfamiliar with traditional pro lab tanks. A gallon is quite small for a 'large tank': two and four gallon 'large tanks' were commonplace. When I was an assistant in the 70s, all the B+W went through a tank that must have held at least 5 gallons. We had hangers for up to 8x10 and reels for 35mm and 120. Developer was replenished ID-11, replaced astonishingly seldom.

I had assumed a lift rod and dropping the spirals into a pre-loaded tank, because of fill times (empty times are a lot less critical). Once it's empty, pull the lid off and dump a jug of stop bath into it. The film won't fog, astonishingly. An Ilford party-piece used to be to develop a film; drain the tank; take the lid off; lift out the spirals on a rod; saunter across the room; and drop the film in the fixer.

Cheers,

R.