film curl

[trainzman]

Going back to film camera issues, I have some 30 year old colour negative film that has developed a pronounced curl along its length. It has been stored in sheets in a binder all these years. Other negatives from the same era were stored in accordion folded sheets in boxes and did not develop any curl.

Now I want to scan them to bring the images into the digital age. The flat film is no problem but the curled ones are a bit of a pain to load and scan properly.

Is there a way to uncurl the negatives? I suppose I could store them in other accordion folded sheets for 30 years but I would rather not wait that long. Is the a safe but faster way to flatten them?

I guess ironing them is not an option  

[DarkPenguin]

Is the film fragile?  If not you might consider giving it a week of flat time.

[trainzman]

I put the sheets with the curled negatives in alternating layers, back to back, face to face ()()()()() instead of all facing the same way, (((((((( in a soft binder and placed the whole thing under a box to keep a constant pressure to encourage them to flatten.

It's Kodak safety film 5035 and still as flexible now as when I bought it 30 years ago.

Anybody know how fast this type of film will the curl after it is developed and stored unrestrained?  Has anyone tried to flatten it and how long to get a reasonable flattening?

[trainzman]

Decided to go straight to the source so here is what Kodak said:

Film curl is due to humidity contraction of the film when stored in a
wound configuration at a relative humidity of less than 40%.  This is
most often a temporary or reversible change, and can be correct by
rehumidification of the film. Allow the film emulsion to reabsorb
moisture while in an atmosphere of higher relative humidity.  Use of a
humidifier in a closed room will accomplish this, but be sure that the
mist does not get directed onto the film itself.  The film will unroll
to an extent with rehumidification.  Once this has occurred*, you may
then place the film into an archival storage envelop or sleeve,  place
beneath a weight, and then bring the atmosphere closer to 40-50%
relative humidity to retain its dimensional flatness.

*be sure that the film is not moist to the touch.

So there you have it, not too dry and keep a light pressure on to maintain flatness.

I tried to buy some more of the accordion folding type of negative storage sheets but none of the local photo stores I contacted carry them any more. Seems when closed, they kept just the right amount of pressure to keep the film flat. Has anyone using the binder style of negative storage sheets noticed any tendency of the film to curl after a long time in storage, especially if the relative humidity is low in the house like during our winters?