It seems that you're taking one specific phrase from one previous post very literally despite having been explained that it's not how it works. It's really a matter of absorbing more information than just that single phrase.
If you take a typical film development tank and turn it over manually, the liquid flow patterns will be highly turbulent. There won't be unevenness due to laminar flow issues. It doesn't matter if the tank is also turned along a different axis; just tilting it 180 degrees will do the trick just fine. There's no way whatsoever that this will create laminar flow patterns across the film surface.
I feel like an idiot because I keep coming back to this and it looks like something that should be easy to understand but I'm not understanding. Let me write something that I think is *not* what you are saying, but the concrete example might help clarify my confusion:
(a) Hold the tank vertically. Left hand at the bottom, right hand on the lid.
(b) Grasp the bottom of the tank firmly with my left hand. Rotate the tank upside down, clockwise direction from my POV, allowing it to slide (rotate) across the palm of my right hand. The natural action of my wrist imparts both inversion and about 45 degrees of rotation.
(c) Left hand is now on top, right hand at the bottom. Loosen the grip of my left hand, and grips the lid (now at the bottom) firmly with my right hand. Rotate counter-clockwise to return the tank, and my arms, to their original vertical orientation. This time, the tank slides (rotates) across the palm of my left hand. The natural action of my wrist, combined with the hand switch, imparts an additional 45 degrees of rotation. So while the tank is right-side-up again, it has now rotated 90 degrees along its major axis.
I feel that at this point I've described steps (1) - (3) in your post. At step (4) I get lost. At the end of my step (c) my left hand is at the bottom, right hand on top, and I cannot impart a further counter clockwise rotation because my arms just don't bend that way. Perhaps I am supposed to switch hands? --- Hold the bottom of the tank with my right hand and the top with my left?
To highlight that point, here's the diagram from Kodak instructions --- I forget which product this is from; probably a Kodak-branded chemical made by PSI.
View attachment 407160
Here's a similar diagram from the C-41 kit:
View attachment 407161
Clearly, a simple inversion is perfectly sufficient. The fact that some of us are discussing more complex rotations doesn't mean that complexity is necessary.
I feel like an idiot because I keep coming back to this and it looks like something that should be easy to understand but I'm not understanding. Let me write something that I think is *not* what you are saying, but the concrete example might help clarify my confusion:
(a) Hold the tank vertically. Left hand at the bottom, right hand on the lid.
(b) Grasp the bottom of the tank firmly with my left hand. Rotate the tank upside down, clockwise direction from my POV, allowing it to slide (rotate) across the palm of my right hand. The natural action of my wrist imparts both inversion and about 45 degrees of rotation.
(c) Left hand is now on top, right hand at the bottom. Loosen the grip of my left hand, and grips the lid (now at the bottom) firmly with my right hand. Rotate counter-clockwise to return the tank, and my arms, to their original vertical orientation. This time, the tank slides (rotates) across the palm of my left hand. The natural action of my wrist, combined with the hand switch, imparts an additional 45 degrees of rotation. So while the tank is right-side-up again, it has now rotated 90 degrees along its major axis.
I feel that at this point I've described steps (1) - (3) in your post. At step (4) I get lost. At the end of my step (c) my left hand is at the bottom, right hand on top, and I cannot impart a further counter clockwise rotation because my arms just don't bend that way. Perhaps I am supposed to switch hands? --- Hold the bottom of the tank with my right hand and the top with my left?
Note that the illustrated tank is a small one, easily grasped in one hand.
I usually use a 1 litre Paterson tank, which is a bit harder to agitate with a single hand.
You hold the tank between your palms. Your fingers just steady it. All the motion comes from your arms and wrists.
In his example you look like you’re driving, turning right, then left.
My technique is one hand, holding the tank with index finger securing the lid on.
I’ll do three full right and left actions (whish whoosh, whish whoosh, whish whoosh), on the fourth I rotate right, then come back to vertical and hit the butcher block hard. Whish, whomp whomp whomp. Then return to the bath.
Do I understand correctly that Matt's method is just doing 180 degree inversions? Similar to the Kodak diagram I posted, except with two hands? ... i.e. My hands could be glued to the tank, just like my hands could be glued to the steering wheel of my car.
Watch how Analogue Andy agitates film on his YouTube channel. No inversions just a classic figure 8 swish. My Dad used this method for 50 years. Didn't have a tank that could be inverted.
I wonder how they agitate film on the international space station. We got easy here on 1g Earth
Andy has a huge catalog on Youtube.....any specific one you're referencing.
This has been quite the discussion triggered by the word inversion.........
View attachment 407176View attachment 407176
SOMETHING LIKE THIS. ALL THE OLD KODACRAFT TANKS DIDN'T INVERT
That's how we agitated with the old Kodakcraft and Ansco, maybe Yankee tanks as well. Most of the 50s and 60s consumer plastic, backbite, tanks did not have caps, or cap leaked so badly that the the figure 8 motion, or the Anso tanks that came with a cheap thermometer that could be to turn the reel inside the tank. Here is an image of one with a regular turning insert. I think the thermometer was extra?Watch how Analogue Andy agitates film on his YouTube channel. No inversions just a classic figure 8 swish. My Dad used this method for 50 years. Didn't have a tank that could be inverted.
I wonder how they agitate film on the international space station. We got easy here on 1g Earth
That's how we agitated with the old Kodakcraft and Ansco, maybe Yankee tanks as well. Most of the 50s and 60s consumer plastic, backbite, tanks did not have caps, or cap leaked so badly that the the figure 8 motion, or the Anso tanks that came with a cheap thermometer that could be to turn the reel inside the tank. Here is an image of one with a regular turning insert. I think the thermometer was extra?
View attachment 407178
That's how we agitated with the old Kodakcraft and Ansco, maybe Yankee tanks as well. Most of the 50s and 60s consumer plastic, backbite, tanks did not have caps, or cap leaked so badly that the the figure 8 motion, or the Anso tanks that came with a cheap thermometer that could be to turn the reel inside the tank. Here is an image of one with a regular turning insert. I think the thermometer was extra?
View attachment 407178
Andy has a huge catalog on Youtube.....any specific one you're referencing.
This has been quite the discussion triggered by the word inversion.........
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