Troubleshooting My Bad Processing Technique -- Scratches

[dpn]

Hi all,

I've been lurking for awhile here, and finally got the courage up to buy an inexpensive LF kit. I'd appreciate some advice on how to improve my large format development technique. I process my film using the Taco method in a Paterson tank -- four sheets of 4x5 to the tank, emulsion side in, and the elastic ties don't have any metal bits. I try to be gentle, but I've been surprised at the number of deep scratches I seem to be producing in my negatives. The weird thing is that the scratches aren't uniform; in my last batch, one negative had many bad scratches, one a couple of deep ones, and two were pretty much okay. I haven't found any spurs or rough spots in the tank, and the scratches aren't in any pattern. Here's a quick example:

112793

Any ideas? I'm tempted to order a Mod 54 adapter, but would like to save the cash if there's an easy solution. My suspicion is that there isn't a quick fix, but that I just need to keep practicing!

Thanks all in advance for whatever thoughts you might have.

-- Dan

[Leigh]

Hi Dan, and welcome aboard.

Yep, that's a deep scratch.

Scratches can be caused at any point, from the time the film is removed from its box/bag until it's dry.
The first thing to figure out is the step at which the problem occurs.

The scratch appears to be caused by a sharp corner sliding across the emulsion (or vice versa).
Try to identify suspects in your loading and processing scenarios that might cause this.

- Leigh

[Bill Burk]

Hey Dan,

I agree with Leigh's observation, looks like a sharp film sheet corner sliding across a wet sheet of film.

What are you doing to wash? When I first started out developing 4x5 in trays, I'd put film in trays and just leave it there with the water running.

Soon enough I switched to fully attended wash cycles and this kind of gash is a thing of the past for me.

[Doremus Scudder]

Billl has a point about washing. If you are letting the sheets just randomly float around in a tray, you are asking for trouble :(
There was a thread somewhere here or at APUG where someone posted about using clear plastic CD racks for 4x5 film. The film fit in the slots perfectly and the whole rack was then submerged in a tub of some kind. Kind of like an improvised Gravity Works film washer. Might be worth looking into.

You might also be gouging when loading/unloading your tank. Probably, however, the scratches are occurring when the film is wet.

Just be very careful that nothing, especially the corner of another sheet, comes in contact with the flat surface (especially the emulsion side) of the film.

Best of luck finding your problem,

Doremus

[dpn]

Thanks all for the replies and ideas. I'll focus on the washing, and make sure my inversions are less ... zealous ... next time.

[Brian C. Miller]

Thanks all for the replies and ideas. I'll focus on the washing, and make sure my inversions are less ... zealous ... next time.

Washing out the hypo is pretty much done by leaching. Just change the water once a couple of minutes, and start with a hypo clear wash.

You can make your own single sheet holder for development (http://www.largeformatphotography.info/forum/showthread.php?64766-DIY-4x5-single-sheet-holder-for-trays) if you are even a little handy with tools. You can expand the design, and do four at a time in a larger tray.

[ic-racer]

Are you using a hardening fixer, if not it might help.

[NancyP]

Here's the wash rack:
30-CD acrylic rack
http://www.containerstore.com/shop/collections/mediaStorage/cDs?productId=10010451
The box to fit it - I just tried the various plastic storage boxes in the store, and found one that fit perfectly. If you have a deep plastic dishwashing basin at home, that would work just as well.