Agitation and Rinsing questions

[photophorous]

Hi Everyone,

I recently got the Kodak darkroom data guide and when I read the paragraph on agitation I was surprised at the frequency it suggests. They say a tank should be inverted 5-7 times in 5 secs, every 30 seconds. I took a class and the teacher taught us to agitate much more gently...more like 2 inversions in 5 secs. I know that increased agitation will increase contrast, but which is more important...the duration of agitation?...or the intensity of agitation? I've been agitating gently, but I think I've been going too long each time...more like 7-10 seconds. I'm trying to understand if that would create more contrast than a more intense agitation for a shorter time, or less?

Another thing I'm curious about. When it comes to the final rinse of the negatives. Is there ever a problem with the water being too turbulent...too much flow? Could that cause inconsistencies in the negative? Is it possible to wash off part of the emulsion so part of the negative appears faded?

I've had a few problems in the past that I can't explain with any certainty, so I'm still trying to understand how these details affect the negative. Any information you have would be greatly appreciated.

Thanks,
Paul

[Asylum Steve]

Paul,

Film development agitation is simply one of the variables in processing. The manufacturers give guidelines to use as starting points. You then evaluate your results, keeping in mind how YOU want your negatives to be then maybe make adjustments.

As you note, agitation frequency and strength affects negative contrast. It also affects film grain.

Now some folks like more contrasty negatives as it will give a print a bit of "pop". OTOH, many prefer a softer, more detailed negative, figuring the contrast can always be increased by using harder grades of photo paper. To each his own...

The numbers you mention, 5 inversions in 5 seconds every 30 seconds are perfectly normal. I think with my Ilford film, I did 10 inversions in 10 seconds every minute, which works out roughly the same.

As for rinsing negatives, yeah it IS possible to damage the emulsion of your film in the final rinse, but it's highly unlikely. And that's more a factor of water temperature than rinse time. Using hoter water in a long final rinse increases your chances of doing damage.

Keep the final rinse around room temperature and you'll be fine. Also, be sure to use a hardener in your fix (only with film, not prints). This make the film emulsion more resistant to damage...

[another view]

Steve H has a lot more experience with this than I do, but I think that it's important to be consistent with whatever you do. I've never been to a class on developing - I just read a lot about it and gave it a try, so I'm not sure what everyone else does for agitation. I inverted the canister 180 degrees (turning my wrist), about three inversions in five seconds. I've heard of anything from two inversions in 60 seconds to five in 30. However, no book can really show the exact motion that someone else does, how hard they shake the canister, etc. I've also heard of people spinning the canister instead of inverting it but never tried it.

Again, if you start playing with variables (and by all means, try anything) then you'll learn a lot more if you change only one variable at a time. This means keeping your agitation technique the same but maybe altering the time or number of inversions. Next time, try a different variable but whatever you changed before make sure to do as your "standard method".

I have really hard water where I'm at and used only distilled water for all processing - including rinsing. Ilford has an archival method of rinsing that is (I think...) filling the tank with distilled water (at the same temperature as all of your other chemestry), doing 20 inversions and dumping the water. Then re-fill it and do 10 more. Then re-fill and do 5 more and you're done. It saves a lot of water and always worked fine for me.

[photophorous]

Thanks for the info, guys. I only do a roll about once every 3 weeks, so the learning process is so slow it's driving me nuts. Wish I had more time.

On my most recent roll, I noticed some frames are lighter on the outside edges than in the middle area. I've seen this before. Could that be caused by agitation? Too much, or too little? Could it be temperature control? I've never used a water bath on the tank. I get the chemicals down to 68 degrees, before starting, but I'm sure they warm up a few degrees during processing. Could this explain lighter edges? I would think a slight rise in temp would effect the whole roll uniformly as long as I agitate properly?

It seems like I always get some good frames and some bad ones, no matter what I do.

Thanks,
Paul

[photophorous]

I just thought of another potential cause for the light edges I described below. Could oil from my fingers cause it? If I get oil on the outside edges, while I'm applying pressure to roll the film on the reel, could that be enough to slow down development at the edges?

Do you ever use those white cotton gloves when loading the film on the reel? Maybe I should try that.

Paul

[another view]

I'm really not sure what would cause that so I'll let the experts handle that. I really doubt it's fingerprints - I never used gloves to load a reel and never had a problem. Clean hands yes, but no gloves. If the lightness on the edges is even, that would pretty much rule it out too I'd think. I used stainless reels and put a little curve in the film by sliding the edges of it thru my index finger and thumb on my right hand while holding and turning the reel with my left. With that method, you're really not touching the film itself - just the edges which won't matter.

[Asylum Steve]

On my most recent roll, I noticed some frames are lighter on the outside edges than in the middle area. I've seen this before.

I'd have to see the negs to make an educated guess, but it could be 1) uneven development caused by a lack of proper agitation, 2) improperly loaded film that presses up against the reel in spots preventing the developer from reaching it, or 3) too little solution in the tank, so the top edges of the film aren't covered in developer the entire time.

If the lightness is uneven, but at regular intervals, it's most likely number 2...

[photophorous]

Thank you all for your suggestions. I've had this same problem with many rolls of 35mm, but also a few rolls of 120. I developed a roll of 120 (my third time, ever) this weekend and it came out great. I increased my agitation and measured more carefully to make sure I was filling the tank properly.

For anyone else who might have similar problems, here's what I did:

Agitation: Inversions - passing tank for one hand to another, giving it a slight twist each time. Initially, I did 15 inversions in 15 seconds, then I did 4 inversions in 5 seconds, every 30 seconds.

Tank level: SST tank, for 1 roll of 120, I used about 15 oz of working sol'n. This was enough to cover the reel completely, but still leave a bit of air when the lid is on.

Time: Recommended time for TMAX 100 / D76 (1:1) at 68 degrees is 9.5 min. I began pouring the chemicals out of the tank after 8:45 and the development looked very slightly less than "normal." This is exactly what I was going for, so I couldn't be happier.

Loading 120 film on reel: I found an easier way to do this, so I want to share. This is not my idea, but I can't remember where I read it. Basically, don't use the clip. Just hold the film in place (near the clip) with your finger, and start rolling. After about 1 revolution there's enough friction to hold it in place and you can let go. Since it's not held tight by the clip it will align itself automatically and stay on track. Much easier this way. I had no crimping or alignment problems.

I hope this is repeatable. I'll be posting a few of the pics tonight when I'm at home.

Thanks again!

Paul