Agitation techniques...

purple · Sep 2, 2006

Being a self-taught darkroom entusiast, I sometimes question the techniques I have developed. I've done a search of the previous posts and was unable to find an answer to a question I have on agitation:

Considering rotation and inversion agitation, which one should be used when? And what are the effects of each type of agitiation?

Most of the time, I shoot ACROS (35mm) and develop in Rodinal 1+50 or 1+100. I use rotation for fifteen seconds every minute for eleven and a half minutes. What difference (if any) would there be in using inversion over rotation?

What difference does it make for other speed films and developers? In particular I'm curious about any comments on Ilford HP5 and Perceptol.

Claire Senft · Sep 2, 2006

This is, I suppose a poor way to start answering this thread. I have four open tanks prebath, developer, stop and fix. I work in the dark with open tanks. My reels are on a lifting rod. I gently lift the rod about 2 inches and allow it to settle. I repeat this for the agitation cycle. I am very careful not to twist the rod while lifting. Not twisting the rod assures me that the inside and outside of the reels get the same agitation. It also protects against surging developer going thru the sproket holes.

I hope that your rash is all gone, never to return again.

purple · Sep 2, 2006

Claire Senft said:
I hope that your rash is all gone, never to return again.

It has indeed. I'm putting it down to a combination of factors. Since I've started using the Nova Trimate, I've not had a problem. Lovely piece of kit, could be built a little sturdier though.

Can I enquire which format you're working in with this technique? It sure as hell doesn't sound like 35mm

Claire Senft · Sep 2, 2006

I am using it for 35mm. Works great!

dbltap · Sep 2, 2006

I agree that the twist method may not give even development. Myself, I slide my tank around in a figure 8 motion. I seem to get a good slosh in the tank. Inversion method doen't work with my tank, and didn't seem a logical method.
Jim

purple · Sep 2, 2006

dbltap said:
Myself, I slide my tank around in a figure 8 motion.
Jim

I take this to mean "keeping the tank in a vertical orientation, moving the tank in a swift movement to trace the pattern of a horizontal figure of eight".

Using quite sharp movements to agitate by momentum?

removed account4 · Sep 2, 2006

when i adjitate 35mm / 120 i move my arms in a figure 8 motion too, and move the tank like i am rocking a baby. i used to use the rod up/down when i had a large tupperware ( food storage ) container that i used for film hangers - the rod worked very well, but the hangers gave me trouble so i stopped altogether. when i got rid of the hangers i went back to the figure 8. slow and deliberate motions ... 10 seconds every minute ( first minute continuous ) ... sometimes i barely adgitate at all or i use a "unicolor" rotary processor to continuously adgitate film in a coffee-based developer. ( don't use the rotary processor for much of anything else )

Solarize · Sep 2, 2006

If you are having success using your current method of agitation then I probably wouldn't change it. A consistant process across rolls will allow you to produce results that you like and find predictable and repeatable. That said,it isnt really an answer to your question.

I use a twisting/inversion type method. I havent really considered the science behind it,but it works just fine. With so many variables to keep tabs on, I've decided to be consistant in my agitation techniques and play with those that will give more pronounced and measurable effects.

Bob F. · Sep 2, 2006

I would guess that intermittent inversion would result in better movement of the developer away from the emulsion's surface compared to intermittent rotation, but I do not know if it makes a detectable difference in practice. I always used 4 inversions (in 10 secs) every minute as described by Ilford, but these days I use continuous rotation in a Jobo which requires a shorter time.

Cheers, Bob.

srs5694 · Sep 2, 2006

As others have said, if you're satisfied with your results, just stick with your current method. To add my personal experience data point, though, I use inversion agitation exclusively; I've never used rotation agitation. Part of the reason for this is that most of my tanks (two stainless steel and one plastic Russian tank) don't support rotation agitation, although I suppose I could use the slide-it-around-on-the-table approach without actually rotating the spools. I know of at least one tank design (another type of Russian tank than the one I've got) that can't be used with inversion agitation; it's a rotate-only design. The point of all this being that sometimes your equipment will dictate a particular approach to agitation -- or other darkroom practices, for that matter.

drpsilver · Sep 2, 2006

02 Sept 2006

I echo the above comments. Find a method that works for you and keep to it until something tells you to change, i.e. any processing faults. I use an inversion/twist agitation for 10 sec every minute similar to what Ilford recommends. The only time I use rotation is when processing sheet film.

One suggestion to see how uniform your agitaton techniques is to photograph a uniform surface (a gray card works well) such that it fills the frame. After processing carefully look at the negative for streak, or light areas. Finally, print the negative (full frame) to at least 8x10 to approximate the density of a gray card. Examine this print for light or dark steaks, dark circles, and other non-uniformities. If this print looks uniform without any major flaws you are doing a good job of keeping fresh developer near the film during processing.

Regards,
Darwin

Claire Senft · Sep 3, 2006

I agree with Darwin with a provisio. Make certain that your diffuser or condensers ar spotless first so that the issue is not confused in case there is mottling.

Blighty · Sep 3, 2006

I remember seeing a TV programme yonks ago on how to develop films. This guy (For some reason I keep thinking it may have been Barry Thornton) was demonstrating his agitation technique. Basically he did x number of inversions at the start of every minute (can't remember the exact number) but, crucially, he gave the tank a little twist while it was upside down, repeating the same action for the given amount of inversions. I've used this method for years with 120 and 35mm and never had a problem.

Agitation techniques...

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