Twist agitation - has anyone ever done tests?

[AgX]

But I learned that the first generation of Patterson tanks could only be used with swizzle stick, not inversion.

Daylight tanks in general started just with twisting the reel, being only light- not water-tight.

 

[Arvee]

So I suspect that the reason Patterson recommend swizzle at first is because it is fast.

I think you're spot on. Sure would help our understanding of the efficiencies of the various agitation techniques if Paterson would give us an explanation for a twiddle cycle initially! It can only be assumed they did formal testing to come to that conclusion. Sure would be nice to know why.

 

[MattKing]

if Paterson would give us an explanation for a twiddle cycle initially! It can only be assumed they did formal testing to come to that conclusion. Sure would be nice to know why.

It is far more likely that they came to that realization eventually, after customers started complaining.
One of the features of the original Paterson tanks - introduced more than 70 years ago - was that they were designed:
"to allow the whole spiral with its immersed film to be lifted a few millimetres, by pulling upwards on the funnel, and subsequently lowered again, therefore "giving efficient two-way agitation", i.e. both rotary and up & down. This was the first stage of improving agitation during film development that led to total inversion agitation by the second tank Series."
This is courtesy of the Photo Memorabilia site: https://www.photomemorabilia.co.uk/Paterson/Developing_Tanks.html#anchor1stGen

 

[AgX]

One of the features of the original Paterson tanks - introduced more than 70 years ago - was that they were designed:
"to allow the whole spiral with its immersed film to be lifted a few millimetres, by pulling upwards on the funnel, and subsequently lowered again...

The first Jobo daylight tank is nearly 100 years old, already with a rotating reel.
I got no idea when they introduced the stick, it was at least 60 years ago, then combined with an automated little lift, though so little that it likely was intended rather as ratchet action.
But who knows.

 

[Adrian Bacon]

I don't frequently use my Paterson tanks any more except for the odd roll that comes in with a request to use Rodinal or some other developer other than my standard, but back when I did use them I was what you could label as an Ardant supporter of inversion method.

Since then, not so much... I've mostly done the twizzle method and haven't seen any difference. The key is to do it suddenly, and don't do it for too long. You just need to get fresh developer onto the emulsion, not mix the whole thing up, and that only takes a quick twist of the wrist.

I was curious about how much I would've needed to agitate with the stick, so I put a test roll in a tank, left the lid off and filled the tank with a liter of water, then put a drop of food coloring into the water and got to seeing how much twirling would mix it up.... You'd be shocked and amazed at how little it took before the entire inside of that tank was the same color. It was a real eye opener for me and led me to just start with one sudden full turn of the stick for agitation.

 

[AgX]

But that the tank got water of seemingly same colour does not necessarily mean that that good exchange at the film surface takes place. Here you could get mislead by your set-up of the experiment.

 

[Adrian Bacon]

But that the tank got water of seemingly same colour does not necessarily mean that that good exchange at the film surface takes place. Here you could get mislead by your set-up of the experiment.

Maybe, maybe not. The fact that the food coloring sitting in the one drop at the top of the tank at the start made it all the way down and stained the film with just a few twists tells me a lot though. Think about it, the film wound on the spool is basically a pump when you rotate the spindle and it mixes up almost the entire tank with just one reasonably aggressive full turn of the spindle. You can actually see the turbulence on the surface of the water at the top of the tank. Obviously, how vigorously you turn the spindle will affect this, but I've seen enough from my experiment to know (as well as looking at actual film processed this way) that a solidly fast full twist every 30 seconds or so is more than enough to get fresh developer onto the surface of the film AND keep the full tank mixed up. There's no need to swizzle for 5-10 seconds, just give it a quick full turn and let it sit. A lot of the problems arise because people are agitating for too long. Be reasonably aggressive, keep it short.

This being said, people will disagree, and that's fine. They should do what works for them, I've found that twizzling works just fine for me.