Dev Time, Rotation (Sub), Pre-soak (Add) and TMAX400 curl

[JWMster]

Using JOBO reels and 2500 tank, I took a standard working time for 120 6X6 rolls of TMAX in Perceptol 1:1 recommended for tone, and given the source works with INVERSION, made a 15% reduction for ROTATION on my Uniroller base. Reading through threads here (and/or on the Rangefinder Forum - not sure which), I found mention that TMAX is not a fan of pre-soak.

On the other hand, John Tinsley's "The Rotary Processing Manual" pretty much dictates the virtues of a 5 minute pre-soak. So went back to that. The trick I found on deeper reading, was that a pre-soak with some films (not all? maybe just crystal or t-grain?) is that adjustment (time extension) is needed to allow for the absorption of water in the pre-soak. I couldn't find a number, but decided to go with 20% added. So given the net of a 15% reduction and 20% add, I came up with 105% of the recommended time. Could have just assumed a 15% minus and 15% plus to offset and go with standard recommended time unadjusted, but didn't. Maybe I'm ornery? Images came out fine. Will have to work with this to refine the time, but it worked and contrast was generally good.

In confirmation that water absorption must have an impact, I found that after hanging the negs to dry from the usual metal alligator clips (I use one at the top and one on the bottom), I was a bit horrified on inspection some 30 minutes later to find the film had an edge to edge curl. Never seen this before. I reversed the clips and a couple of hours later it went away. But I assume some of this may have been due to pre-soak? I've not even read of this mentioned anywhere, but maybe I just hadn't paid much attention.

So I'm thinking time extension to address pre-soak is the right thing with TMAX. But I don't know whether this is normal or not. Your experience?

 

[Konical]

Good Evening, JWMster,

I have processed many hundreds of 4 × 5 sheets of both T-100 and T-400, almost all by rotary method. I've also processed a lot of T-Max roll film, both 120 and 35mm, using SS tanks with the typical intermittent agitation. Perhaps surprisingly, I have found that my processing times with both T-100 and T-400 are just about the same with each method, in spite of the usual recommendation for about a 15% reduction for continuous (rotary) processing. I do use a two-minute pre-soak. The great thing with the T-Max films is that they are both sensitive enough to plus or minus developing to be very adaptable to various contrast ranges.

Whether with T-100 or T-400, I have never encountered the slightest curling problem with either 120 or 35mm, but I doubt that the use or avoidance of a pre-soak would make much difference. Nor does it seem likely that either rotary- or inversion-processed film would be more or less prone to curling. Could your particular humidity conditions perhaps be having an effect??

 

[MattKing]

A pre-soak changes things slightly.
Changing from one to another form of agitation changes thing slightly.
Those slight changes may add to each other, or may counteract each other.
Don't change your times, unless your negatives tell you to. In many cases, they won't, or won't tell you to change them much.

 

[MattKing]

And by the way, a pre-soak will have absolutely no effect on how the negatives dry.

 

[JWMster]

Konical: Humidity was 45% if that makes a difference.
MattKing: KISS: Yes, I'm beginning to see how even with all the hullabaloo, the science of exposure and densitometry, the chemistry of film and its development, the KISS method works better than getting tied up in knots.

 

[MattKing]

Yes, I'm beginning to see how even with all the hullabaloo, the science of exposure and densitometry, the chemistry of film and its development, the KISS method works better than getting tied up in knots.

KISS is good.
But equally important, we don't have enough control over the variables to be able to reliably predict how much adjustment might be needed to compensate exactly for the changes.
If you were talking about a highly controlled, commercial operation with high end, high volume equipment and narrow tolerance process testing, it might be possible to quantify the differences.

 

[JWMster]

Matt: EXCELLENT point. Thanks! And as much volume as I'm cranking... you're right it ain't enough to make a very scientific sample.