C41 Agitation Questions

[bvy]

I'll be launching in to C41 this weekend. I plan to follow Kodak's instructions as closely as the Rollei Mini kit will allow. I have a few questions.

1. It takes me a good ten seconds to pour the developer and cap my Paterson tank. Should I start the timer as soon as I pour the chemicals, or when I begin agitation?

2. Kodak suggests two quick inversions (at one second per inversion) every fifteen seconds. They don't mention knocking out the air bubbles, as I do with black and white. Is this unnecessary since agitation is more frequent (than black and white)? Or should I do it anyway? I don't think I want to be too aggressive.

3. Regarding the bleach and fixer steps -- I'd like to do these steps with the lid off and agitate with the twirly stick. I've read about leaky lids, the need to "burp" the tank, etc. Are these steps more forgiving as it relates to agitation type? -- i.e. Do I risk streaking (or some other ill) by twirling versus inverting?

Maybe I'm overthinking this or worried too much. But thanks just the same!

 

[newcan1]

I wouldn't take the lid off until halfway through the fixer. What's the point?

 

[bvy]

You have to take the lid off to use the twirly stick. It's still light tight as long as the funnel's in place.

 

[markbarendt]

As long as it is light tight it's fine to remove the fill cap. The bleach is the step that requires venting.

As to agitation, "normal" C41 development done in commercial labs is a constant agitation process of one type or another.

When I started and used hand agitation I used the method you described and put the tank back in the water bath between agitations, worked ok.

As I refined my developing process with a larger bath I switched to rolling my floating tank constantly on its side in the water bath. I was using stainless tanks so had to gently keep the lid on worth my fingers, roughly 1 rotation every 2 seconds worked fine for me. Be consistent.

Developing, as I'm sure you know, is time critical both directions, so 3:15 unless you are pushing or pulling, I start the clock as soon as I stop pouring, I start dumping at 3:00, at 3:15 I start pouring in the bleach.

The bleach and the rest of the processes go to completion so the times suggested are simply minimums, extra time, say doubling, doesn't hurt a thing.

For the bleach in hand tanks I did not lay the tank on its side, tilt and spin were the motions with the fill cap off. Your stir stick with the occasional tilt should work fine.

Fixing and final rinse/stabalizer can be done either way, cap on.

 

[bvy]

Thanks a bunch, Mark. I plan to use the Kodak times for bleach/fix; they're about double what Rollei suggests -- six minute range.

And it sounds like circular agitation won't cause streaks during these steps.

As far as developing, is it as critical to tap the tank to release air bubbles on the film as it is with black and white? (Maybe I'm splitting hairs now. I've been reading about this stuff all week.)

 

[markbarendt]

I tap with hand tanks on the first agitation.

If the tank is rolled on its side it is typically only half full, the horizontal rotation takes care of the issue.

Changing up the agitation, reversing the rotation, tilting, inverting, can help avoid wierd stuff.

 

[mtjade2007]

Development time should be 3 min 15 sec including the time of pouring the developer into the tank and draining of it at the end. But if it takes you 10 seconds to pour the developer you may want to add 5 sec to the development time.

 

[bvy]

Thanks everyone. Three rolls in, and my workflow is now as follows:

-10:00 - -:05 - Place empty (of liquids) Paterson tank in tempered water bath (weighed down; water is ~118F)
-:05 - :00 - Remove tank from water bath and remove lid from tank
:00 - Pour developer (~101F), start timer
:05 - Move tank back to tempered water bath (~113F now)
:05 - :30 - Twirly stick agitation
:30 - :40 - Cap tank
:45 - :47 - Agitate: two inversions; tap tank to release air bubbles

I continue agitation every 15 seconds but only tap again at 1:45 and 2:45. The tank is in the water bath at all other times.

3:00 - 3:02 - Last agitation; do not replace tank in water bath
3:02 - 3:15 - Remove lid, dump developer
3:15 - Pour bleach...

I did numerous dry runs and tested the temperature at various places. It seems to average about 100F.