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Process Control. Graph - "All over the shop"


photocorp
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Hi all.

Need help....

This concerns  our Theta 51, but is relative to all mini-labs as a general topic

What started out as a simple problem of dirty prints, hasn't been resolved so I'd appreciate a few comments from the forum.

Theta was due for a major PM anyhow, so replaced most upper rollers, dumped all chem, replaced filters and tanked up with fresh processing solutions. Prints are improved but whites are not white. Still have this persistent off-whitish  "stain". Hardly noticeable until you compare with the other 4 labs we have at our facility.

Sreen dump of the  Q-lab graph  attached showing the trend(s).

All temps, repln rates, are OK, speed is 45 secs for Kodak RA Dev (stop-watch). I'm thinking maybe a little starter might help the dilema? or conversly add more dev.

What do you think.......

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Oh golly a Y55  :) And very nice to see a lab doing plots .. OK if you look at the LD (d-min) and your Stain, the plot shows a problem. For me, this would indicate a dev problem. Your dev activity is running lets say <low>

First thing that I would do, well take out your dev filter. Check it and double check it.

Dump your stab, dump 100% (its cheap so do it) replace the stab filters all of them.

If the stab issue fixes the problem, then check the carry over from the bleach to the stab.

Try these first.

(as ever I ain't responsible if things do not work)

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From your plots the last thing you want is more Starter, Your D min is a bit high but your LD is low

When did you dump the Dev?

Dirty Stabilizer can give you a dirty yellow white but your LD dropped 6th Feb, before that it was shall we say, robust.

Not wanting to teach my granddad and all that, did you get the correct mix for the CD tank solution, Kodak Started bottles have 3 or 4 different ratios for starter, water etc depending on the CD, SP, SP LORR etc

Depending on tank capacity a boost of fresh dev would help your LD without severely changing Contrast (HD-LD)

Last thought on the whites, stale paper? Not knowing your throughput, maybe the wider paper is not used as quickly as your other machines.

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Thanks for the feedback Magenta and Neil.

FYI

Our labs are plumbed from 800litre holding tanks, we mix every 3rd day so all printers are fed from the same source. For us it's a simple matter of dumping any particular tank, wash and then turn on the supply tap to tank up with fresh working solutions. Dev of course must be mixed as prescribed with the correct amount of starter and water.......and maybe this is where I made a stuff-up accounting for the D-min issue.

We are a high voulme consumer of  paper and only use one type in all machines, that being Kodak Digital  Professional (Brilliance).

Probably should drop the dev and start over?

As for the muddy off-white stain....well guess I should take another look at the Stabiliser rollers and /or Bl carry over.

We untertake major mechanical maintenance (rollers and belts etc) quarterly co-inciding with school vacation periods, and change working solutions once yearly when the tanks are scrubbed.

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Good Luck

I know its a bit off topic But we used to mix in a similar way and in our case, had weired cross curved results on all the kit drawing off the main holding tank.

We dropped and remixed and got the same results only to find by accident that the guy who mixed the Dev, one day had missed Part B, a large 20 odd litre container of chemistry, so he through it in the trash.

Not very bright as it was still full and didn't move when more trash was thrown in. We had roasted lab technician that night more for him not telling any one. It was always the rule screw up fine, but tell us so we could put it right. O how we laughed

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Hi Photocorp

I agree with Neil and Magenta a dose of extra Dev will help the LD (Red and green plots) top two layers. The D-min (stain) changing the stab may help, also if the B/Fix is a little under repped the stain does increase (Adding 20% B/Fix rep to the tank won't do any harm).

Often just running with the problem will help as stains start to deminish after a while.

Hope this helps.

Denis

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