Heat Drying Films Question.

Read the post in this thread by "From the Hollar" where he mentions that heat drying films can affect graininess.

I haven't heard of this before, so I am asking here, does heat drying films affect graininess?

I ask because I dry my films in a film-drying cabinet set to a warm temperature.

http://www.flickr.com/groups/dianaphotos/discuss/72057594088826515/

I have a powered film dryer, without heat. I can see where possibly heating the film emulsion after its been at 68f could cause problems, graininess and maybe even reticulation, if the temp is high enough to shock the film.

Heat drying does NOT affect film. All commercial processors for B&W and Color use heat drying by either hot air blowers in roller transport processors or heaters in banks in rack and tank processors. This has been known for years to be a safe method of drying film. Overheating can cause curling and uneven drying so the drying must be uniform and moderate to keep from affecting the support and emulsion.

I have never heard of reticulation being caused by drying, but I suppose it could happen. If it did, the heat would have to be extreme and you would then see other problems including the curling and distortion of the support. The reason I doubt this is that the evaporative cooling effect will tend to cool the film as the water evaporates under heat. This tends to keep the film from damage unless you get over (guess) about 140 - 160 F within the film, not at the dryer which could reach 212 F or higher at the exit of the air directed to the film. The temp drops rapidly as ambient air mixes with it and cools it.

PE

Photo Engineer said:

Heat drying does NOT affect film.

All commercial processors for B&W and Color use heat drying by either hot air blowers in roller transport processors or heaters in banks in rack and tank processors. This has been known for years to be a safe method of drying film.

Overheating can cause curling and uneven drying so the drying must be uniform and moderate to keep from affecting the support and emulsion.

I have never heard of reticulation being caused by drying, but I suppose it could happen. If it did, the heat would have to be extreme and you would then see other problems including the curling and distortion of the support. The reason I doubt this is that the evaporative cooling effect will tend to cool the film as the water evaporates under heat. This tends to keep the film from damage unless you get over (guess) about 140 - 160 F within the film, not at the dryer which could reach 212 F or higher at the exit of the air directed to the film. The temp drops rapidly as ambient air mixes with it and cools it.

PE

Click to expand...

The temperature of my film dryer is only set around 40*C (I think). I will look through the technical manual to make sure.
I have never noticed any difference between using the heater on or allowing the films to dry unheated. The comment in the link made me wonder if increased graininess was possible with moderate heat drying.

I've read somewhere, but have no reference to give now, that drying with hot air helps long-term preservation of slide film. In my Jobo Mistral 2 I have three positions: room temperature, 35 °C and 45 °C. I use the warmest position to dry my 135 slide films.

The films get very curled after a while, but it reverts back to a gentle curvature when it cools down. I leave the film to dry at "high" temperature for more than half an hour, then let it cool down blowing air at room temperature while keeping it hanging with the weights.

The slight resulting final curvature does not disturb the usage I do of the film and actually allows an easier placing of the film stripes inside the paper sleeves. I suppose that if I let the film dry at room temperature it would come out perfectly flat, but would not bet the farm on that.

Fabrizio

I use heat from molted lava to dry my film!

Jeff

Diapositivo said:

I've read somewhere, but have no reference to give now, that drying with hot air helps long-term preservation of slide film. In my Jobo Mistral 2 I have three positions: room temperature, 35 °C and 45 °C. I use the warmest position to dry my 135 slide films.

The films get very curled after a while, but it reverts back to a gentle curvature when it cools down. I leave the film to dry at "high" temperature for more than half an hour, then let it cool down blowing air at room temperature while keeping it hanging with the weights.

The slight resulting final curvature does not disturb the usage I do of the film and actually allows an easier placing of the film stripes inside the paper sleeves. I suppose that if I let the film dry at room temperature it would come out perfectly flat, but would not bet the farm on that.

Fabrizio

Click to expand...

High temperatures may accelerate the reaction of E6 films with the Formalin in the process, but it is designed to work without the extra heat.

The curling and uncurling indicates over drying and then absorption of moisture to reach equilibrium with the ambient air. This is normal.

PE

Photo Engineer said:

Diapositivo said:

I've read somewhere, but have no reference to give now, that drying with hot air helps long-term preservation of slide film. In my Jobo Mistral 2 I have three positions: room temperature, 35 °C and 45 °C. I use the warmest position to dry my 135 slide films.

The films get very curled after a while, but it reverts back to a gentle curvature when it cools down. I leave the film to dry at "high" temperature for more than half an hour, then let it cool down blowing air at room temperature while keeping it hanging with the weights.

The slight resulting final curvature does not disturb the usage I do of the film and actually allows an easier placing of the film stripes inside the paper sleeves. I suppose that if I let the film dry at room temperature it would come out perfectly flat, but would not bet the farm on that.

Fabrizio

Click to expand...

High temperatures may accelerate the reaction of E6 films with the Formalin in the process, but it is designed to work without the extra heat.

The curling and uncurling indicates over drying and then absorption of moisture to reach equilibrium with the ambient air. This is normal.

PE

Click to expand...

My drying cabinet has a heater, but no thermostat. During the summer, when the room is warm, the inside temp is about 115.

Should I turn the heater off and just air dry? The humidity where I live is pretty high normally. Should I try to control that, too?

Michael;

At 115F there is NO problem.

PE

Jeff Kubach said:

I use heat from molted lava to dry my film!

Jeff

Click to expand...

After the Lava molt they can leave track marks on the film and the hairy bits can get stuck on the film. But if they are moth Lava they will fly away after they molt.