View Full Version : Processing Defect-Bubbles?

28-Feb-2017, 13:42
This is another roll film question from me, but it's something that I seem to have been struggling with lately. I've also noticed it a bit on sheet film, but there again it's less obvious on smaller formats.

I seem to have a problem of spots along the bottom of every frame. I get a few all over the frame seemingly, but the worst concentration is at the bottom. I've been doing some mental gymnastics to see whether that would be the top or bottom of the roll when it's in the tank. When I load a roll, I generally hold the roll in my left hand and unspool it into my right hand. I then put the spiral in my left hand, and feed from my right hand. The reel then gets dropped in the tank as-is. The problem is especially pronounced in 35mm, but I see it medium format and even in sheet film also. If I'm thinking right, that would make these defects actually at the top of the roll in the tank since they appear on the bottom of the frame. It's not camera specific-in fact I've been "exercising" a lot of 35mm bodies from my "collection" that either haven't been used in a while or that I've never used lately.

For reference, I generally use an old Omega two roll tank and Nikkor reels, although I've been known to use a Yankee Clipper. I use the SP455 for 4x5(notch in the top right in the hanger). My standard developer is D76, either straight or 1:1 depending on the situation. I use 9 oz. for a single roll of 35mm and 16 oz. for two rolls or a single roll of 120.

I'd appreciate any thoughts on what might be happening here(and yes, the scratch is my fault-it's a reminder of why one shouldn't use a squeegee).


28-Feb-2017, 13:48
It's not bubbles. This is caused by physical particulates or more accurately "crud" that is stuck to the film. You should clean all of your processing equipment really well and filter the water used for developing and fixing your film.

1-Mar-2017, 11:12
Thanks for the response-it looks like I have some investigating to do.

I'm pretty diligent about scrubbing my reels with soap and a toothbrush after every developing session and then soaking them for a while in hot water. I also rinse my tanks in hot water(and take down the SP-455 completely) and let everything air dry before I use it again.

Water around here is notoriously hard. I do use tap water for my developer and fixer, but perhaps I should switch to distilled or deionized. The film above was processed in D76 that's about 3 weeks old, and I'd made a batch of fresh fixer(from Ilford concentrated rapid fixer) earlier that day and that was the first roll of film where I'd used it. I read an argument a while back from a Kodak engineer on photo.net who argued for using tap water to mix chemistry. I don't recall his exact reasons. I do know that they struck me as being chemically sound at the time, so I've continued to do that.

For my final rinse, I usually open the tank and circulate water through it for several minutes. I then do a final dunk in Photoflo 1:200 in deionized water(with a very tiny amount of phenol to prevent bacterial growth) and hang it to finger squeegee. That is unless I do something stupid and use a film squeegee, but I won't be doing that again...

I hang my roll film vertically in the shower. I put a coat hanger on the curtain rail and clip the top from that, then use either a binder clip or a proper darkroom developing clip at the bottom to weight it so it's straight.