Streaks from rotary processing

[dave_schneider]

I have been processing 4x5 sheets of FP4+ in old Cibachrome drums for

some time now. In the Cibachrome drums I have installed tiny ridges

of plastic to hold the ends of the film, these are about 1/16 inch

square strips of plastic the full length of the drum. I have on

occasion seen a few streaks which raised my curiosity. I ran a sheet

uniformly exposed at Zone V last night and sure enough there are

streaks. They are very faint and appear in direction of rotation. Do

I need to use more end to end rocking motion of the drum while it is

rotating or is rotation speed an issue? I use a home made roll stand

consisting of some model car wheels and rotate by hand. About every

30 seconds I lift one end slightly and then reverse direction,

rotation speed is about 10 RPM, maybe more if I had too much coffee.

[jay_de_fehr]

Have you tried using a water bath instead of your home made stand? Fill a small tub with water at your processing temp. and rotate there, BTZS style for more random action.-jdf

[dave_schneider]

I had not tried the water tub since the Cibachrome drums have the drain holes close to the edge. The drums would float low enough in the water to get water into the drum and dilute the developer. I had thought about mounting one of the wheels off center to give it rougher ride.

[gary_frost1]

What quanity devloper are you using? Is it close to the drum minimum?

If so, try using more developer to 'bury' the film in it.

[dave_schneider]

I use 200mL of solution which makes the depth at the bottom of the drum while rotating about 10mm. Any more solution and it would spill out the drain holes in the end of the tank.

[donald_f_degen]

According to the Jobo website (www.jobo-usa.com) streaks in rotary process drums are caused by drops of water in the drum. They have a complete article on this and strongly recommend to make sure your drums are completely dry. These ridges you added sound like ideal places for water droplets to hide. Did this problem start after you added the ridges or have you "always" had the streaking problem? If always, is the streaking problem now better or worst? A pre-soak water bath may help, I always use a water bath.

[steve_feldman]

Dave,

 

I think we've all had that problem. My problem was developing in trays. Streaks, uneven dev. and scratches. Also boring. Rocking trays in the dark. I had heard about the Uniroller print drum and motor base. Yes, that's correct - 4x5 negs in the PRINT drum.

 

I figured that if the 4x5 / 8x10 print drum took paper of that size, it could also accommodate 4x5 film. It does. And very well too.

No modifications necessary. Just follow the loading instructions with the drum. That is . . . insert a sheet with the emulsion facing the interior of the drum, one edge against the "v" on the inside edge and the other against the plain stop. 2 sheets can be loaded side by side on both sides of the "v" to equal 4 sheets.

 

I just fill the drum with as much as it will hold (about 16 oz.) or until it dribbles out. It works fine. Never a bad neg. . . . . . . . yet.

 

Note: I'm developing 4x5 b & w only . . . no color. For 35mm and 120 film I'm using the same motor base with Patterson tanks and reels.

Hope that helps.

 

-S.

[scott_eaton]

I'm going to guess that this drum is basically an 8x10 paper drum, or something very similiar.

 

Older, slow speed films like Plus-X and FP4 are notorious for streaking in sheet format. I honestly think you could pick up patterns in the earth's magnetic field because of the sensitivity these films have to developer agitation dynamics in sheet form. I spent an entire summer pulling my hair out with a similiar problem at a commercial lab and became a local expert into bromide reactions and developer proximity effects. I fixed the problem by loading film into foot long pieces of PVC pipe and then dunking them in tanks of developer. Agitation, being both rotational and vertical eliminated the problem. When we switched to a rotary wing-lynch, the problem never returned, no doubt due to the design of their film holders.

 

A couple things I can think of that might help. First is pre-soaking, and the next is switching to TMX 100. The newer Kodak film is far less prone to this problem. Adding more agitation counter to the flow of developer is another idea as well. More tilts and less rotation as you suggest.

 

Perhaps the biggest fix I can think of is to create a baffle to prevent developer from moving at a perfect vector across the film's surface. If I visualize your contraption correctly, the inside is basically a perfectly smooth cylinder save for the tiny pieces of plastic used for holding the film. Nah, that's not going to work. Developer is going to race over those film notches and cause all kinds of havoc.

 

I'm thinking something like this: get some 1" PVC pipe, cut it the length of the tube, and glue them inside the length of the tube as close to the film holder tabs as you can. The PVC pipe will act as a baffle and disrupt the flow of developer from going straight over the film as you rotate.

 

John Sexton had some really good articles on the subject and came up with some really cool contraptions for solving the problem. Most involving tray development though.

[dave_schneider]

Thank you Mr. Eaton for your informative post. You surmise correctly that I took a Cibachrome print drum and added the little ridges just to hold the film at the edges. I had thought about adding some internal baffles that would disrupt the circular flow motion but thought this would cause a whole new set of problems. I had built a slosher similar to the one sold by Summitek. I used vertical plastic rods to hold the films in place and saw swirl marks along the margins of the film where those rods were placed. That was when I started using the Cibchrome drums which was an improvement over the slosher. I picked up some ABS piping at the home store today and will try the individual tube approach ala BTZS next. I really don't want to switch to TMAX, I like FP4+ in 120, I'm just having difficulty developing it evenly in 4x5 sheets.

 

As to your suggestion do you mean to put a 1" diameter pipe in the drum lenghtwise near the edge of the film? As thr drum rotates this would sort of make a dam such that the developer would spill over the edge as the dam approaches the top of the rotation and then spill on the the film that is at the bottom of the rotation. Might be worth a try.

[jeffrey_scott]

For the last several years I have been using Jobo Expert Drums to process film in sizes from 4x5 to 8x10, with a Beseler Motor Base, with excellent results. I make sure I have about a liter of chemistry in the tank to ensure even development. It may be more expensive than going to the hardware store and jury rigging various means for processing film but the results are well worth the extra expense. Besides, it is a one time purchase that down the road you will be saying "How did I manage to do without this thing!?"

[scott_eaton]

<I>As to your suggestion do you mean to put a 1" diameter pipe in the drum lenghtwise near the edge of the film?</i><P>Yep. Just take into account that developer will flow into the tubes and you'll probably have to strategically place a few drain holes - AWAY from the film. <P>This might result in an increase in density towars the inside of the film because of flow eddies, but's it's likely to be more diffuse than annoying straight lines and swirl patterns. A pre-soak can't hurt either, but only unless your process times are 6' or shorter. <p>Even the interaction of developer flowing over the edge of B/W sheet film by itself can cause problems. I wish John Sexton had those articles online because he really did some superb trial and error on the topic. Please give us a follow-up if you can.

[richard_walker]

I've been using Cibachrome drums to develop 8X10 FP4 and HP5 without experiencing these problems. My method may differ from yours:

 

1) I use between 400ml and 600ml of developer as a one shot solution. This is not enough to cause an overflow through the air vent on the cap.

 

2) I use an Ilford motorized revolving base (ebay cost: £7.50).

 

3) I use a water bath pre-soak for all negatives.

 

I know the UK Ilford product is slightly different from the US product, although I cannot say precisely how it differs. It looks different in illustrations.