Mottled spots on film

[Henry Friedman]

I just finished open tray development of 4 sheets of 4X5 TMX and discovered 1 mottled area of underdevelopment on three of the four. The spots were circumscribed, oval or roundish, perhaps 1/4 to 1/2 inch in size, and of variably lower density than the surround. It is as if the developer didn't reach these areas to the same extent as the rest of the negative.

My technique is as follows: 1 minute pre-soak (shuffled twice in tap water to initiate the pre-soak), then constant agitation in Xtol 1+2, followed by the usual acid stop bath, fix, wash aid and wash. The Xtol was mixed fresh 18 hours prior to use. This technique has served me well for hundreds of negatives in the past.

Thanks to all for any insight into this problem.

[Paul Moshay]

The acid stop may have caused that effect. Just use plain water and you won't have that problem.

[Brian Ellis]

Why would an acid stop bath cause a single thin, mottled area in three out of four negatives as described here? Acid stop bath in theory can create a pin hole effect but I don't see why it would cause the problem as described here. It also wouldn't explain why he's processed hundreds of negatives without any problem and now has the problem only with these three out of four negatives.

Unfortunately, while I don't think that stop bath is the problem (if I'm understanding the problem correctly from your description) I don't know what is. It might be helpful if you could post a picture. Among other things, is the spot in the same place on all of them? Is it possible that your shuffling method was lax and developer didn't reach these areas?

[Henry Friedman]

Unfortunately, I am unable to post pictures. But these are certainly not pinholes; they are much larger and do contain some (but uneven) density. I don't think my shuffling was lax; I lift each sheet by a different spot on each rotation through the stack, and rotate the stack 90 degrees after every third rotation. I think this is "by the book". In two of the three cases the spots are in areas of sky that seem otherwise very evenly developed. In fact, all of the negs were otherwise just fine; no streaks or scratches or uneven anything. And the spots are in different locations on each sheet.

I have heard of (but can't recall seeing) air bells on roll film but can't imagine how this could apply when the sheets are constantly moving across one another.

Thnaks again.

[Brian Ellis]

Sorry but I can't help and apparently no one else can either. My best guess would be some kind of defect in the film.

[Robert Tilden]

Is it possible that you had some oil or other contaminant on your finger(s)? The description sounds sort of like a fingerprint's -er- footprint.

[Brian C. Miller]

Perhaps you scratched your nose, picked up some oil on your finger, and then handled the negatives. A momentary touch could have left enough oil on a finger to cause a development problem.