Emulsion side water marks?

Hi I hope all is well.

I keep encountering what appears to be stains or water marks on the emulsion side of my film. It seems to only show up in the drying process. I have had this issue on and off and it is quite frustrating as I have changed nearly every variable. My process is as follows.

(All steps are done with distilled water)
Develop
Stop 30 seconds
Fix 4-6 Minutes
hypoclear 3 Minutes
Ilford Wash method (I do 15-25-40)
Final Rinse in distilled water
Hang to dry

I have tried Edwal LFN, Photo Flo, and no wetting agent and still get these marks. They are never on the base side though. They come and go, and I have absolutely no clue what causes them. The only other thing I can think of is potentially the low humidity, but I haven't heard of others having this issue.

I have provided images below of some recent scans. I cropped in on the sky where it is most noticeable. The last image is of an exposed piece of film where the marks are the worst.

Humidity - or lack of it - when you are hanging the film to dry.
You need to have a drying environment where the air isn't too dry.
That and a carefully mixed wetting agent.
What film is it, and what format?

MattKing said:

Humidity - or lack of it - when you are hanging the film to dry.
You need to have a drying environment where the air isn't too dry.
That and a carefully mixed wetting agent.
What film is it, and what format?

Click to expand...

35mm Kentmere Pan 200 is the film shown in these images. However, this seems to happen with all types of film. My question is how humid does it have to be? The average indoor humidity here is 20ish percent.

Try the Photoflo at 1/2 strength and do not squeegee/wipe the excess off, but let it sheet down.

If you have an enclosure for drying the film, place a small bowl of water in the base of the unit.

When you say you tried Photo-Flo, how much did you use?

A favorite discussion of mine, led me to use 1 cc to 500 ml

The marks are likely due to uneven drying. Use a wetting agent (PhotoFlo) and make sure you are using the right amount. You need enough to break the surface tension and prevent drops from forming on the film. Usually, the recommended dilution works fine, sometimes you can use a bit weaker. Finding the right dilution helps; often, especially if you don't squeegee your film, excess wetting agent can cause uneven drying and these marks.

Mix your wetting agent with distilled water. If you have any question about the hardness of the water you process with, soak your film in the distilled water/wetting agent solution for five minutes with gentle agitation. This will better leach out minerals than the 30-second rinse often recommended. Oh yeah, discard your wetting agent after one session.

And, despite what you'll hear from many here, remove excess water from your film. I squeegee my film up to 4x5 sheets between two clean and soft fingers. I don't do larger now, but a windshield wiper works great for larger film and prints (new and gently applied, of course).

If that doesn't solve your problems, it's likely not due to drying marks.

Best,

Doremus

Kino said:

Try the Photoflo at 1/2 strength and do not squeegee/wipe the excess off, but let it sheet down.

If you have an enclosure for drying the film, place a small bowl of water in the base of the unit.

Click to expand...

I use a shower stall, run the hot water shower before I hang the film, and then pull the curtain to limit air flow until the film has had a reasonably long time to come close to drying.
In our relatively temperate climate, it is relatively easy to deal with. Tucson, Arizona might need extra care.

I have never known water marks to form on the emulsion side of the film. Could these perhaps be marks caused by something else?

cliveh said:

I have never known water marks to form on the emulsion side of the film.

Click to expand...

It's reported from time to time, but rarely. The most plausible explanation I've seen (IMO) is that they're differential drying marks that occur when drops of water cling to the emulsion and take much longer to dry than the surrounding emulsion. This can apparently lead to minor deformation of the emulsion, which shows up as density variations. The solution in this case would be to prevent drops of water clinging in isolated spots to the emulsion. A wetting agent might help a d I understand some people hang the film at a slanted angle instead of vertically, so that water doesn't run down the entire length of the film and get sort of stuck in a droplet halfway and then dry out there, but instead reaches an edge early on.

Mind you, I've never actually had this happen on my own film, so the above is all second-hand information. YMMV and all that.

I’ll throw in my experience with drying marks. The water can make a big difference as will the wetting agent dilution, at least for me. Where I lived growing up I just used tap water no problem, I don’t think I even used a wetting agent. Where I live now (SoCal) I had to figure out something new because of marks. LFN half strength in distilled water did the trick in the end.
It’s not that dry here so I don’t know about the humidity thing, but that certainly sounds plausible.

I used to struggle with drying marks despite using wetting agents like Photoflo and LFN and hanging my film to dry in a shower that I’d steamed up. I then started gently squeegeeing my film using Kimwipes and I’ve never had a drying mark since. Kimwipes are very gentle and have never scratched my film. I just fold up a wipe into about a 1/2” strip, wrap it around the film strip and gently squeegee the length of the film. Most of the water sheets off the film and the remainder is absorbed by the Kimwipe so there’s almost nothing left. I still leave the film to dry for 24 hours before cutting it into strips and filing it.

Doremus Scudder said:

The marks are likely due to uneven drying. Use a wetting agent (PhotoFlo) and make sure you are using the right amount. You need enough to break the surface tension and prevent drops from forming on the film. Usually, the recommended dilution works fine, sometimes you can use a bit weaker. Finding the right dilution helps; often, especially if you don't squeegee your film, excess wetting agent can cause uneven drying and these marks.

Mix your wetting agent with distilled water. If you have any question about the hardness of the water you process with, soak your film in the distilled water/wetting agent solution for five minutes with gentle agitation. This will better leach out minerals than the 30-second rinse often recommended. Oh yeah, discard your wetting agent after one session.

And, despite what you'll hear from many here, remove excess water from your film. I squeegee my film up to 4x5 sheets between two clean and soft fingers. I don't do larger now, but a windshield wiper works great for larger film and prints (new and gently applied, of course).

If that doesn't solve your problems, it's likely not due to drying marks.

Best,

Doremus

Click to expand...

My hands and fingers are much too ruff-ruff to be anywhere near a film emulsion. I guess I should sell the dishwasher and do the dishes by hand so my hands can be as soft as yours.
With 35mm and 120 I use LFN and distilled water, then shake and hang to dry over our laundry room sink with about four to five inches of hot water in it. With my 4X5 and 8X10 film I do pretty much the same thing, but hang it diagonally from one corner to dry. I haven't had a single problem since doing it this way. Knock on wood!

koraks said:

It's reported from time to time, but rarely. The most plausible explanation I've seen (IMO) is that they're differential drying marks that occur when drops of water cling to the emulsion and take much longer to dry than the surrounding emulsion. This can apparently lead to minor deformation of the emulsion, which shows up as density variations. The solution in this case would be to prevent drops of water clinging in isolated spots to the emulsion. A wetting agent might help a d I understand some people hang the film at a slanted angle instead of vertically, so that water doesn't run down the entire length of the film and get sort of stuck in a droplet halfway and then dry out there, but instead reaches an edge early on.

Mind you, I've never actually had this happen on my own film, so the above is all second-hand information. YMMV and all that.

Click to expand...

^^ This

I'm with Logan2z on this - except I use Webril pads, which come on a roll and appear to be compressed cotton. I unroll an 8"x8" pad, fold all the perforated edges into the inside. Then I draw the "pad" over each side one at a time gently, emulsion first, changing the pad inside out in between. Never a scratch or streak since. A roll will last nearly a lifetime.

Aidan Gravelle said:

My question is how humid does it have to be? The average indoor humidity here is 20ish percent.

Click to expand...

I live at high elevation where the humidity is typically quite low (around 25-30%). I struggled with similar drying marks for quite a while despite, like you, adjusting every variable I could think of. Ultimately the solution was reached by drying the film in a space where the humidity could be artificially elevated. I bought one of those self-assembled gym-style lockers off of Amazon and turned it into a film drying cabinet. Because it's an enclosed space, you can increase the humidity by simply placing an 8x10 tray of hot, steaming water in the bottom of the locker about 10 minutes before you've finished processing your film. That gives the air time to become humid and warm, and also helps cut down on any dust that may be floating around inside. I added a digital hygrometer to the locker so that I could see real-time readings of the humidity inside, which will typically start out at about 70% when the film begins drying, and then will taper down to around 45% after four or so hours of drying. This completely eliminated the problem with drying marks for me.


To echo and expand upon what Matt King wrote above, the problem with drying marks arises as a consequence of how film dries. There are two primary processes at play: 1) slippage of water droplets from the surface of the film under the influence of gravity (a comparatively fast process); and 2) drying of the gelatin and base material via evaporation (a comparatively slow process). Ideally, you want the droplets of water on the surface to completely slip off the film before the gelatin and base material become too dry. This is aided by the use of PhotoFlo, provided the humidity is high enough (e.g., >50%). But in low-humidity environments, what happens is the gelatin and base material dry faster than normal, which causes the surface of the film to become rough and tacky. That tackiness prevents the surface droplets from cleanly slipping off the film, so some of the dissolved minerals and chemical residues get stranded. By artificially elevating the humidity, you keep the gelatin and base material adequately wet for longer and give the surface water more time to cleanly slip off the film.

@Scott J. that's a pretty solid attempt at explaining the mechanics involved. You may very well be right!

koraks said:

@Scott J. that's a pretty solid attempt at explaining the mechanics involved. You may very well be right!

Click to expand...