Hang-dry film - how long?

After processing I simply hang the film from a frame in the middle of

my room. Is there any way to tell when the film is dry and I can put

it into sleeves? A rule of thumb, like "the same time it takes a

light/medium weight/heavy cotton fabric to dry out"? I live in the

east, so humidity in the room varies greatly, from close to 100% in

the summer to very low in the winter. I apologize if this question has

been asked before, my search turned up no answer. Thanks in advance

for all advice!

I hang my film in the bathroom overnight. (This room is the most dust free I can find). You could easily see if there is any moisture on the film. But just to be sure i cut the last 1/2 inch or so closest to the filmclip before I take the film down.

I was under the impression that the emulsion on the film has a certain thickness and may be still wet even though it appears to be dry. Visible water usually disappears from the film very quickly, within an hour, but I'm afraid that's not enough.

3 hours is usually enough for me, however humidity plays a significant role. I would think 5 hours would be plenty.

Once the film is dry to the touch it should be dry! Anyplace still wet just doesn't look the same. When the film is dry there's no chance of dust sticking to it like with wet film so I sometimes run a hand hair dryer over it for a couple minutes, about a foot away and constantly moving. This is just to make sure it's really dry. It's humid here in South Florida too.

I hang my film from a ceiling fan. Dry enough to sleeve within an hour, tho' I often leave it overnight. No dust problems.

I used to use the 'pinch test', i.e. I pinch the bottom bit of the film below the last neg and if it isn't tacky then the film is dry. But as someone suggested it may be wise to let it dry for an hour or two after it feels dry to harden the emulsion. If you can, get hold of an old changing-room locker and use that as a drying cabinet. A 100 watt lamp will provide heat and air movement - but make sure water doesn't drip on it !!

Sprint makes a negative drying solution (mainly alcohol based) that is used after the final wash. Other than that, I used to have great luck and dried film in 15 minutes with a contraption I made out of a hanging garment bag. The ones you can buy in any store like Kmart that has a square frame on the top with 3 hangers and a clear front that also has a full length zipper (used for storing cloths in for the winter). I pooked a hole in the top and put a hair dryer in that hole and took a sharp knife and pooked a few small slits in the bottom so the air could run out. A few clothes pins and you have an excellent drying cabinet that folds up to nothing when done!

You don't have to touch the film to tell if it's dry. As 35mm film dries,

it first curls toward the base side, then "pops" with the curl toward the

emulsion. When it is uniformly curled toward the emulsion, it is dry.

Michael's right. The film bends and then straightens out, with a slight curl toward the emulsion. Make sure to clip a clothes pin to the bottom of the roll to keep it hanging straight down. As others have said also, if you touch the emulsion (in a clear space with no image of course!) you can tell if it's dry. Don't rush things though, make sure it's bone dry. No need to spoil good negs because of impatience. I hang my film in the kitchen, and if I'm really in a hurry to see the negs I turn the oven on and open the door to it about 6 feet away from the film- works great.

I guess it's really hard to put a "time" for 35mm film emulsions to dry. The real problem is the ambient conditions. I have never had spot problems I use photo-flo I hang in the bathroom with a clothes pin at the bottom the visual curl mentioned just above is a good visual clue, but even that isn't fool proof sometime though dry to appearance, and slides into the pergamin sleeves easily, but if not completely dry I then get a lot of littler white specs on the negatives. This is clearly the pergamin paper residue sticking to the film...not sure which side, ie emulsion. I then have to re- wash the now "cut" negatives and then they're ok. Bit too much work to have to was twice. .. I guess err on the too long drying time and risk ambient dust

 

 

 

Before; note the specs in the foreground ..not the badly focused subject

 

 

 

 

 

 

After re-wash ; - ..so obviously the specs are from the paper sleeves.

I suspect that the film has dried since the question was asked in 2002.

 

Local factors are so important (humidity, temperature, etc.) that it is hard to give a general rule, except to err on the side of longer, rather than shorter time.

"How long for film to dry?"

As long as it takes.

I've only self developed about 20 films so far, I hang it in a pre steamed shower, usually about 5 hours or overnight. It seems that about 3 hours is sufficient, but I try to leave it for 5. I observe the same behavior others posted that at first the film hangs straight, then it curls heavily even though it appears dry on the surface and then eventually it straightens out again. The film then goes either directly into a scanner or a sleve for scanning later. So far I've had zero issues with dust. It's extremely rare that I see any. This to me was one of the benefits I didn't expect when starting self developing - the ability to avoid dust on film. I must say though that I send my color film to Praus Productions and the film from his lab comes back extremely clean as well; had some horrible experiences with various other dev studios I tried. Edited April 28, 2021 by pavelkupcik

Over 50 years of B&W developing experience ( I don't want to count how many rolls, but it's in the thousands along with thousands of sheets of 4x5) I also have almost never had a dust problem. I have always been careful to leave the room where I hung the film to dry and waited patiently until it was fully dry, usually an hour or two. Like most aspects of B&W processing, it isn't rocket science--it just requires reasonable care.

When I was briefly assistant to a Wedding Photographer, we'd process the films from the wedding, then he'd put them (120 format) in an old storage locker, under which he had placed his wife's hair dryer set to 'warm', with a 'filter' made from several layers of her old tights. Using this state-of-the-art equipment, the film could be dry enough to proof in fifteen minutes, ready for the Reception. No idea of the permanence of films treated thus, but their use was reasonably transitory anyway - all negs were binned after a year.

When I was briefly assistant to a Wedding Photographer, we'd process the films from the wedding, then he'd put them (120 format) in an old storage locker, under which he had placed his wife's hair dryer set to 'warm', with a 'filter' made from several layers of her old tights. Using this state-of-the-art equipment, the film could be dry enough to proof in fifteen minutes, ready for the Reception. No idea of the permanence of films treated thus, but their use was reasonably transitory anyway - all negs were binned after a year.

 

The data sheets give the maximum dry temperature, and I am sure that commercial processors use heated drying.

 

I have used a hair dryer for RC paper, but never for film. I wasn't in that much of a hurry.

 

Another way is to dip it in alcohol, which will replace the water, and then evaporate faster.

In that case, I am not sure that there isn't any change in permanence. I learned that in a school optics lab.

I am sure that commercial processors use heated drying.

You bet they do!

For small scale commercial processing you could once buy drying cabinets of various sizes. These were generally along the lines of a full-height metal gym locker with a fan and heater element in the bottom, or attached as a 'power bulge' to the outside. The air-inlet had a fine filter, and the outlet a simple louvre and mesh affair.

Another way is to dip it in alcohol, which will replace the water, and then evaporate faster.

I read about using methylated spirit to dry film when I was about 15 and, of course, had to try it. It doesn't really work well, because meths has a small water content that gets left as beads on the film. So you just get spotty negs.

 

I also read about a newsman's trick for super-rapid drying. To set fire to the meths-soaked film. The theory is that the flame-induced rapid evaporation keeps the film cool. I tried that as well, on a short length of scrap film. Definitely not recommended! :eek:

I think we did it with ethanol, which may or may not make a difference.

 

Yes, I don't think it works for film, but I have seen it done as a science demonstration with a dollar bill.

 

With the usual 70% or so alcohol solutions, there is enough water to keep the dollar bill cool,

while flames are on the outside. I think dollar bills survive higher temperature than film.

 

For TP2514 it says up to 140F. Other films might be different.

I usually begin processing film in early evening, hanging up to dry over night. Use lead weighted clips to reduce curl. Time to dry roll films about the same. Sheet film seems to take a little longer because I let film remain in development frames. But in morning all are dry.

I think we did it with ethanol, which may or may not make a difference.

Methylated spirit is about 95% ethanol, with the addition of pyridene to give it an incredibly bitter taste, and methylene blue dye, which gives it its name. Contrary to popular belief, it doesn't contain methyl alcohol.

 

Ethyl alcohol is quite deliquescent and difficult to keep 'pure' without it absorbing a fair percentage of water. Anyway, I was generally in no desperate hurry to dry my film. So such pyrotechnic shenanigans were a one-off experiment.

 

FWIW. Last time I processed Tmax100 (about a year ago) I was surprised how quickly it dried - only about an hour until it was touch dry. That was after finger-squeegeeing the surface water from it and at room temperature ~ 21 degrees C.

Edited April 30, 2021 by rodeo_joe|1

Methylated spirit seems not to be a common US name, so I was just suspecting it was methanol based.

 

For ethanol, 95% is the best you can do with distillation, and so that is what you commonly see.

The bottles that you get for lab use have a tax stamp on them. (In the US, anyway.)

Higher than 95%, they have impurities that you don't want to drink, and no tax stamp.

 

I remember learning this in a thermodynamics class, where the professor explained to us,

which one to get when raiding the lab before a party.

 

In the US, we have "denatured alcohol" which is ethanol with some things intentionally

added that you don't want to drink, and that are also not easy to separate out.

 

From: Denatured alcohol - Wikipedia

 

it seems that methanol was, at least once, one of the additives, up to 10%.

The can I have of "denatured alcohol" also claims a methanol addition.

 

Otherwise, yes, I often find them dry to the touch pretty fast, but let them dry longer to be

sure that they are dry all the way through.

 

We have a heat pump water heater, which keeps the basement both cool and dry.

In the newspaper business during the film days we often used denatured alcohol to quickly dry film when we were trying to get sports photos out under deadline. We weren’t worried much about long term effects on the negatives but then two of the photographers were often smoking cigars while printing so it was a unique environment all around.

 

Rick H.

I know this is an old thread, but I'll add my input. After washing negatives I let them soak in Photoflow solution for 30 seconds then hang them up. Usually dry in 2 to 3 hours. My darkroom receives air (heating or cooling) from central HVAC so humidity never gets too high.

If you want that it dry rapidly, use isopropyl alcohol with a few drops of Photo-Flo as last bath. It dries in minutes.