agitation -- tank vs drum

[gbogatko]

Could someone venture a guess at a factor that can be applied if one is used to tank development (which allows inversion agitation plus stand time) vs. drum agitation (which doesn't allow any stand time)?

For example, If I'm doing 4x5 FOMA 100 in d76 1:1 at 8 min. in an HP combi-plan, what would be a starting-off factor for the same film in 8x10 using a unicolor drum?

I know, test--test--test, but I'm looking for at least a decent first shot time. I've heard a rough factor of 15-20% between either method.

Thanks,

George

[sanking]

Could someone venture a guess at a factor that can be applied if one is used to tank development (which allows inversion agitation plus stand time) vs. drum agitation (which doesn't allow any stand time)?

For example, If I'm doing 4x5 FOMA 100 in d76 1:1 at 8 min. in an HP combi-plan, what would be a starting-off factor for the same film in 8x10 using a unicolor drum?

I know, test--test--test, but I'm looking for at least a decent first shot time. I've heard a rough factor of 15-20% between either method.

Thanks,

George

George,

I would suggest reducing development time by about 15% with the drum, if using continuous agitation on a motor base.

Sandy King

[Skorzen]

One thing that might be a factor is the speed at which the drum rotates. I found that with TMY I had to cut my dev time by 40% from the massive dev chart times. I think my base may rotate faster than most (it's about 30 RPM), beseler non reversing.

[Darryl Baird]

I have three different agitation bases -- Unicolor reversing, Beseler non-reversing, and a Kindermann that rotates and lifts. In order the Beseler has (by far) the fastest rotation speed, followed by the Unicolor, and the Kindermann is last. A 15% reduction in time is a starting point, but a solid test would be my preference. I seldom use the Beseler, but I cut my time from the Unicolor (my standard unit) by around 10%.

[gbogatko]

Just what I was looking for. Thanks all!!

George

[Paul Jones]

I have just started using the Jobo recommended 5min pre-soak. This allows for standard inversion development times, or close to them. I like the longer processing times and so far so good. When I didn't pre-soak I would reduce processing time by about 15%, depending on rotation speed and developer, as a starting off point.