Are overheated rolls of film (both exposed and unexposed) likely to be damaged?

Question

I'm currently on a camping trip and I have little to none way to keep my b&w film rolls refrigerated. I accidentally left some rolls in my car under the sun near the seaside: I found both the bag in which I kept them and the rolls very hot, I don't know for sure but it may have been about 30° - 40° Celsius

The rolls are

• Exposed Tri-X 400
• Unexposed HP5+
• Unexposed Ilford Delta 3200

The new rolls were kept in their plastic and paper bags, while the exposed just in their plastic bag. Right now I emptied a thermos, refrigerated it with some air conditioning and close the exposed ones into it.

Are the shots in the exposed Tri-X compromised?

Should I avoid exposing the unexposed ones?

Answer 1

Black & white film is pretty robust. Remember it has been around for longer than air conditioning.

In the old photo cookbooks (and even new ones, such as Steve Anchell's) there are recipes for tropical developers - for regular ones don't work in tropical heat. I found no record of tropical film stock; I presume colonial photographers shot with their regular material. The same applies to Ansel Adams, when he spent weeks in a car shooting US West.

TriX and HP5+ can stand a tremendous amount of abuse. Unless you kept your film in heated trunk for very long (weeks instead of days) they will all right. Delta 3200 is more risky, as would be IR sensitive material.

As a precaution: have the film processed as soon as possible.

Answer 2

Photographic film is a perishable. It will be damaged if stored in a hot – humid location. That being said, the damage has been done, hopefully your film has survived. It is difficult in the field to protect the film from hostile conditions. Use a zip-lock bag to protect open films against moisture. Unopened film boxes are protected from moisture by its packaging. Sprinkle of rice in the bag, rice is a moisture absorber. Place the zip-locked film is an empty thermos or insolated lunch box (lunch pack). These precisions can help in the field.

Anyway have the film processed as soon as possible after you get home. What happens is, heat triggers the light sensitive chemicals in much the same way as exposure to light. The end results will be, the film will have its fog level elevated meaning that portion of the film that should be clear will have some unwanted blackening. Hopefully you will be OK as negative film has some reserve capacity to yield an OK print even if abused in storage.