Darkroom Problems: Differential Drying / Water Spots, Air Bells or Something Else?

Darkroom Dilemma: What are these things?

Hey folks, Azriel Knight here with a darkroom issue.

Recently I had problems with my film negatives, and I thought I tackled the issue because I changed a single variable, as recommended from a forum, and it went away for a few rolls but just reared its ugly head. Take a look at this….

This is a scanned negative of the worst from the roll. First I’m going to tell you the characteristics then what I have already eliminated based on research and testing.

As a negative, it is a small white diffused round area. Around it is a dark crescent.

These tend to only appear in the highlights of a frame and do not appear throughout the entire roll, but instead tend to be emphasized at the beginning or end.

Here is what I have eliminated as the cause.

First up, I don’t use tap water during my process. All of my chems are mixed in distilled water except D76 and my entire final rinse is distilled as well. So the likelihood it’s calcium deposits are very very low.

I have used several developers and had the same issue, HC-110, Rodinal and D76 have all had good results, and these not so good results intermittently. When using HC or Rodinal, I mixed with distilled water. D76 though used with tap, had previously good results and was only a couple weeks old.

I have used several films as well, including Tri-X, Ilford Ortho, and P30.

My top suspect was fixer. and when I prepared fresh fixer a month ago, the issue did go away, but when I made it this last time, it came back with a vengeance.

You can imagine this is incredibly frustrating. The last two rolls I did were for two projects, and now I have, what I consider garbage results in about a third of my frames. These are the times where I feel like pulling what some other, more popular photographers on YT have done, and that is mailing out my film, and letting someone else do the hard work for me.

After I was finishing grinding my teeth into a fine white powder, I hit up a Facebook group.

I definitely got some answers, some that seemed more educated than others, the most prevalent comes from a guy we’ll call Mr. B

Mr. B ran a lab for what sounds like at least a decade, and had this to say about it.

“It's a water spot... the technical name is "differential drying" when the water spot causes the emulsion to deform from uneven drying within the water spot”

Then after a little back and forth he goes on to say.

“I have no doubt what this is because... sad to say... we encountered this periodically in my lab. We consulted with everyone, Kodak, Ilford, L.B. Russell, and there were no foolproof answers. It's caused when a droplet of water dries slowly on the emulsion. It causes (if I recall correctly) a microscopic "dimple" in the film, surrounded by an equally minute "ring". Sometimes you can rewash after soaking the film for a little while in distilled water and it will "smooth out" but as often as not it's permanent. When I tell you we tried everything, we tried everything. Increased/decreased humidity, concentration of wetting agents, additives, filtering and distilled water. You name it, we did it. Fortunately it wasn't common but when it reared its head it was maddening.”

This was not what I wanted to hear. Obviously.

While I don’t want to discount Mr. B entirely, the fact that they never came to a conclusion keeps me from thinking this is the issue. Maybe I’m wrong.

I dug through a couple forums, which if you have done, you know it usually means a bunch of “experts” contradicting each other and unresolved posts as old as 20 years.

Squeegee, don’t squeeze, use a paper towel, use a special cloth, hang the film diagonally. Use photo flo, don’t use flo, use half the recommended flo.

While many people could tell you that their entire workflow resulted in a zero issue negative, no one pinpointed the problem without someone else contradicting them in the next message.

In support of the differential drying theory I had the heat into my darkroom blocked off this last time, so it would have taken longer to dry, the humidity was about 35% as well.

The other thing was I had removed my gloves just before hanging and they had been sweating. If sweat and gunk traveled down the negative it would have taken longer to dry than the water.

I am pretty motivated to figure out what is happening here. I could spend weeks changing one variable at a time, but I’m hoping someone here has an answer. Someone who has had this issue directly and can define it precisely.

My next step is to scrub my darkroom within an inch of its life and consider a different drying area. I’ll keep you posted.

Please leave your theories in the comments section of the attach video, and up vote or down vote the other theories.

In the event this issue is 100% figured out, I will update the title to say SOLVED, and leave the answer in the description.

And until next time, stay classic!