Inversion: does it require a full tank of chemicals?

This might be a silly question but here goes.

For years now I've used the two-reel patterson super system 4, agitating by spinning/twisting the center column.
I now intend to get a patterson 8 reel tank. Being such a large tank, it was recommended to me that I use inversion agitation by physically moving the entire tank.
My question is that, say I wanted to process only 4 rolls of film, would I measure out enough chemicals for just 4 rolls, or would I use the chemical equivalent for 8 rolls to ensure that the 4 reels never lose contact with the chemicals when I am making upsidedown inversions? I understand of course that I would still put 8 reels in even though only 4 are filled, to make sure that the 4 do not move independent of the tank.

Make sure that you use the recommended amount of stock per roll of film, which might be more than what it takes to cover the rolls.

You need not be concerned that film never leaves the developer, it's OK to be out for the time you are agitating.

But the big thing to be careful of with Paterson tanks is the rising of the reels. If you use empty reels to hold the 4 loaded reels down, then you have no problem. But if you only cover the 4 reels and they rise up... you will have an obvious problem.

Also there may be some foaming, I would make sure you have enough liquid in the tank to prevent foam or bubbles from ruining the top edge of the top roll.

Damn, Bill beat me to it, but still I'll say no, as long as:
- you've got enough developer per roll (check datasheets)
- you've got enough liquid covering the film
- your reels don't move upwards (some people advocate putting empties on top to fill the tank).

Actually, I've heard people actually advocating this, ie to always use a half-full tank. Something about making it always re-mix the chems properly (which I can understand, in a full tank with 0% air, the liquid won't be as mobile and mix each inversion).
Also watch out, if you've always 'stirred', you'll get different contrast and maybe different developing times when inverting (if you've calibrated enough to notice).

Thanks!

mrksgrn said:

For years now I've used the two-reel patterson super system 4, agitating by spinning/twisting the center column.

Click to expand...

In the instructions, Paterson recommend only using the stick to spin the reel at the start to remove bubbles. It is not recommended to be used for subsequent agitation.

From Paterson Instruction:

After pouring in the first solution, immediately insert the agitator and twist sharply back and forth three or four times, then lightly tap the bottom of the tank on the bench to dislodge any air bubbles which might form on the surface of the film. Now push the cap on and make sure that it fits all the way round.

At the end of the first minute and of each subsequent minute, invert the tank, at once returning it to the upright position, and tap the tank on the bench as before.

Click to expand...

http://35mm-compact.com/manuels/paterson-uk.htm

Steve.

The reels 'should' stay in place however, to block potential movement in a failsafe manner, roll an elastic band down the centre-column to the top of the top reel. When you are limited in the quantity of reels you have, this helps with having dry reels available for the next run instead of using them as placeholders in a larger tank.

APUGuser19 said:

I'd use a 4 tank with the bottom 2 loaded, and use the tilt method instead of full inversion, just to avoid bubbles or oxidation. And adjust time accordingly, if necessary. It's not a cocktail shaker. The idea is to cause re-distribution and avoid swirl flow.

Click to expand...

Could you elaborate a bit more on the technique of tilt agitation? What exactly is swirl flow?

Steve, I didn't realize I had been agitating improperly for years!

Each tank has a volume of chemicals for inversion. Use whatever that is for the film size and tank that you use.