uneven 8x10 negs.

[RTucker]

I am having a problem with developing my 8x10 negs, in a jobo 3005 drum. I am using rollo pyro, with the jobo drum and a uniroller base. I presoak my negs, and add my chemistry horizontally with a homemade funnel-hose set up. But my negs seem to have density build up, around the neg edges, and slightly more towards the "end of the neg" that would have been at the bottom of the drum giving me problems with skies etc. Any suggestions would be of great help to me.

[Filmnut]

Couple things I can think of off hand. How long is it taking to pour in the dev? An excessive time might cause trouble, also, are you using enough chem to properly cover the film?
If you are using a high dilution formula it is possible there is not quite enough dev agent to develop the film fully. How does the image look otherwise?
Are you rolling throughout the development time?
If you could post a scan of the problem, it would help with a diagnosis.
Keith

[mandoman7]

Hopefully, you've checked your drum position with a level to make sure that variable is not at play. Other variables would include the length of the pre-soak, and developer dilution and quantity. I would lengthen the first, and increase the latter and see what happens.

[Vaughn]

Does your motor base have auto-reverse? I disabled the auto-reverse on my Unicolor motor base. Because of the 3006's large diameter, I felt that it was not doing enough rotations before reversing. I manually flip the drum over every minute or so on the motor base instead. I had trouble with uneven skies if I just let the drum spin in just one direction.

I was having problems removing the anti-halation layer -- I ended up with what looked like mineral deposits on the back of the film...not just a little patched of color that is quickly removed by a little fixer in a tray. These depositis are permanent. In fact, after fixing, I would remove the film and put the film in a tray of fixer and would still have the "mineral" deposits. Switching to a non-hardening fixer solved that problem completely. I kept every thing else the same, so I know of no other factor that might have cured the problem.

So I would suggest using a non-hardening fixer if you are not using one already (I just use Kodak Rapid Fixer without the Part B). The added density you are seeing might be silver that was not removed by the fixer -- as opposed to extra development in those built-up areas.

Vaughn

[RTucker]

Thanks for helping me out, I see I that could be doing a couple of things that give me problems. First of all, when looking at my negs they all look great, and all look printable. My prewash is done by having an 8X10 tray beside the jobo drum, both are filled with water, and as I take a sheet out of the film box, it goes into the tray, until all 5 sheets, are in the tray. Next I transfer them into the drum, put the lid on and then dump out the water, so maybe 3-4 mins.
I use 1000ml, water, 15ml part A, 30ml part B dev. I also dump the dev. at the half way point and add fresh dev. again. When I add the dev. through my funnel setup it takes aprox. 15-20sec. which is as fast as I can add it without it spilling out of the end of the drum.
My Unicolor motor base does rotate in both ways, but it does not give a full drum rotation in one spin, but with all the chemistry inside, it seems to be doing its job.
The fix I have been using is the liquid stuff from ilford, that I beleve is non-hardening.
Also I dont do the step of putting the used dev. back in, after the fix, it sounds like this just builds up not needed density, giving longer exposures, and most people have stopped doing this so I am being told.
Many thanks for responding to my problem.

[ic-racer]

Developer exhaustion during the process.

[jeroldharter]

I find that when people describe precisely what they do when processing, they tend to omit the idiosyncratic steps that almost nobody else does. In this case, the pre-soak. You are making the pre-soak much too complicated by doing it in a separate tray. That alos negates one of the big advantages of using Jobo drums - reduced risk for scratching. So I suggest doing the pre-soak in the drum and getting rid of the tray.

This is a good video on 4x5 but basically just do what he does:

http://michaelegordon.wordpress.com/2009/11/05/how-to-video-daylight-sheet-film-4x5-development-2/

I would not trust the reversing mechanism on the roller base. Even if the volume used allows the solution to touch all of the film, the development is still uneven - not every square millimeter of the sheet experiences the same development. That is why I prefer a Beseler roller drum which has a toggle switch for manual change of direction.

There is a fairly simple mod that you can do to the unicolor drum that will fix the problem. You unscrew the bottom and remove the black plastic cover. Inside, there is a simple toggle switch that gets pushed by a lever when the axle rotates. You unscrew the switch (that is the slightly tricky part). Then you use a dremel to slowly cut a window in the black plastic case for the switch to protrude to the outside. There is just enough wire for this to work. Then when you screw the case back on the switch is accessible from outside the case and is held firmly in place by friction. It took me about 20 minutes and I am do consistently sloppy work with DIY stuff. So it was not bad. This is the link I used for that. Look at post #10:

http://www.largeformatphotography.info/forum/showthread.php?t=58911&highlight=unicolor

[Vaughn]

I also do my pre-soak in the drum.

I use to do the soak-the-film-in-the-used-pryo-dev thing. A nice way to make your exposure times long, but that's the only good it seems to do.

Not enough rotation before reversing seems to be the most like suspect so far.

[patrickjames]

I presoak in the drum too with two changes of water to get rid of the anti-halation dyes.

For those who use a Beseler roller base- to be able to reverse the rotation of the drum less often I rewired the internal reversing switch to the secondary front switch. No drilling needed. Although since I am not an electrician, there was a lot of head scratching involved.... Now it works great though and I don't have to pick up the drum to get it to reverse.

As far as your staining problems go, I have had intermittent problems myself using Pyrocat. My problems have been varied though so I can't point my finger at any one thing. They do make me question using staining developers and just use Rodinal which always does a perfect job. I would suggest you try a normal developer just to see what you get.

[cjbroadbent]

I just pour the HC110(B) into the presoak after 2 minutes and adjust time accordingly. Since then no uneven negatives. Bad practice?