tech Q for Mr Mowrey

dr5chrome · Jul 22, 2014

Howdy..

I am assisting in a setup of a minilab E6 machine. While it was a complete mess, we manged to get fresh chems into it. I have been running E6 for years, but in a rack&tank machine. The controls and fresh film come out with a heavy [25-points+] yellow in the DMIN. What bath do I look at 1st that might be causing this problem?? ..this I have never seen before.

Tanks a bunch!

regards,, dw

Photo Engineer · Jul 22, 2014

I would look at the bleach, bath or blix first depending on process. Then I would look at the reversal bath. It is a sequential back step from the bleach in this case.

PE

dr5chrome · Jul 23, 2014

thanks much!.. this is a standard E6 process [not the shorter]. I have tried to dip these already processed films back into the separate baths - yellow still there after each dip-dry-dip-etc.. Since the CD needs the reversal, and the bleach needs the conditioner, we also tried a dip in one bath, then the following[in-tank, then replenisher and visa-vers]. though our bleach stock was older, it checked out [grav.&PH]. The '2' dip - bleach→fix, we did get some clearing. Since the bleach is newer than the fix, I changed out the fix in the tank thinking there was something in the tank that contaminated it - also used a newer stock to remix. I am running strips now. next would be to change the bleach

This machine had an odd set up. '2' small reversal tanks, no wash out of the 1st-dev. So we modified the 2nd tank to a wash tank.

Can the reversal be too short? would increasing the concentration of the reversal compensate? ..or is only a short bath needed?

regards, dw

Photo Engineer said:
I would look at the bleach, bath or blix first depending on process. Then I would look at the reversal bath. It is a sequential back step from the bleach in this case.

PE

dr5chrome · Jul 23, 2014

Update - New fixer - DMIN still yellow. Changing bleach, just for grins - reversal.. running strips now

Rudeofus · Jul 23, 2014

If your reversal bath is bad, you should get poor Dmax, but no issues with Dmin ...

Photo Engineer · Jul 23, 2014

This is changing perspective on me now.

A bad Dmin suggests poor first development, because the FD clears the Dmin my developing silver in the negative Dmax area to completion. Poor development there or some chemical reaction right afterwards will cause colored Dmins. I'm not to sure what to say now except try a few variations such as a wash after the FD.

PE

Rudeofus · Jul 23, 2014

Did I get dr5photo right, that repeating the bleach&fix procedure cleared up some of that yellow Dmin? If that's the case, then this has nothing to do with FD and everything to do with the bleach IMHO.

Photo Engineer · Jul 23, 2014

It actually could be a complex mix of both.

PE

dr5chrome · Jul 23, 2014

I changed the bleach, to fresh bleach we picked up today. While i didnt think it was the bleach, what we had on hand was old. Fresh bleach did improve the situation, but not 100%. First I did think the FD was bad or contaminated, so we dumped and added fresh. I could understand why the designed this machine without a 1st wash... It is possible that in changing this, we cause another issue. I guess adding some kind of burst-air in that 1st wash is in order, as well as adding nitro where there is none.

thanks very much for the replies!

best, dw

Photo Engineer · Jul 23, 2014

You can play with C41, but there is no leeway in E6. It must flow the way the instructions say. So, if you make modifications, you run the risk of bad results. In addition, you might notice that Fuji and Kodak films take different times in the FD and they mean it.

Take another look at the workflow and see if anything stands out. It is hard at this remove to picture the whole thing.

PE

Rudeofus · Jul 23, 2014

Reexposure bath is well buffered, which means that reexposure bath will bring development to a quick stop (pH ~ 6.0), whereas development could go on for a bit in a water rinse. If you really want to rinse after FD, you could try using a buffered stop bath instead. If that doesn't make a difference, at least you know that this extra water bath most likely isn't the reason for your Dmin woes.

BTW a quick and dirty way to find out once and for all, whether your bleach is off, is by rebleaching your test clip in Farmer's reducer. While this could, in theory, cause all kinds of color shifts or whatever, it will reliably clean out all residual silver. If this changes Dmin, you need to do something about your bleach&fix. If it doesn't, the bathes from FD to CD need your attention.

Athiril · Jul 28, 2014

First wash is part of the process and doesn't come to an abrupt stop until reversal bath.

Rudeofus · Jul 28, 2014

Some implementations of E6 process may use wash after FD, but dr5chrome's machine, in its default configuration, seems to skip this step from what I read.

tech Q for Mr Mowrey

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