How quickly will heat fog B&W film?

[albada]

Top strip is the one that was in the van from yesterday morning until this morning, through a very hot day.
Bottom strip was in the darkroom.
Both exposures identical, made this morning. Strips developed together in stock D76.
I can't see any impact the heat had, except the strip that was in the car was more-tightly coiled when I put it on the reel.

View attachment 348315

Don, what kind of film do you use that's numbered up to 40 (your top strip). Or is that a bulk-load? I don't know how bulk-load is numbered.

Mark

 

[Mr Bill]

My point is, while it's great to base an opinion on what you believe and what you've been told (or based on what makes sense), if a simple test can easily decide the matter, why not do it?

I'm glad to see that you've done the simple test to sort of answer things with this specific film.

Regarding "why not" there could be a handful of reasons, one being that for some it's more fun to talk about than to actually find out.

You should keep in mind, too, that there's a great deal of difference in levels of individual experience. Some may already have enough "real world" experience that they can automatically dismiss this as very unlikely. Not that such experience "proves" anything, but when troubleshooting photo problems, something I've done quite a lot of, it's often more effective to start with the things one thinks are most likely. If no answer is found immediately then one might proceed to the less likely things. And on and on.

I once oversaw some similar testing with professional color neg film. As I recall it was before you joined Photrio so probably didn't see it. But you might find it interesting even though it's well outdated by now. I'm sure I can find a link if you're interested.

Basically we wanted to identify how bad a problem we (the company) had with film accidentally left in company cars in hot weather. Including southwest USA in the summer. I initially figured I could cook some film in my own car to approximate what we GUESSED would be typical worst temperatures. No luck getting hot enough; we had mid 90s F ambient temp, black asphalt parking lot, dark red car. I stuck in a couple of temperature probes, the kind you can use on certain digital multimeters, where film might sit, both trunk and inside the cabin. I "knew" from internet lore what to expect. Unfortunately my car was not capable of getting anywhere near as hot as expected; inside the trunk was coolest. So...we converted a metal Coleman ice chest to a temperature-controlled film test chamber, then picked an arbitrarily high temperature that we figured might "break" the film fairly quickly. Guessing that in the desert southwest US, with daytime ambient temps around 110 F, car interiors could easily exceed 130 F, we decided to run the hot box at 140 F (~60C).

Now, it's well-known to pro photographers that professional color neg films are most sensitive to heat, right? (Didn't pro stores need to keep such film in coolers?) Certainly such films will be damaged sooner than amateur films, or perhaps b&w films, right?

Well, we did not include any b&w film in the test, but we ran Kodak VPSIII (predecessor to Portra 160) in both 35mm and 70mm long roll (they used different bases) as well as at least one amateur film. Periodically we'd pull samples of each film, expose test wedges on a calibrated sensitometer, and process all together along with a "control strip" (These are the reference materials that establish the "activity" of the process). Finally we read tri-color densities and made plots for each film type.

Results? You'll have look up the older post. But... after this we realized that there was virtually NO CHANCE that any of our "road" personnel would ever be able to accidentally damage the VPSIII in a hot car. Perhaps not even intentionally.

As a consequence of this sort of testing I am in the group that pretty much sees the likelihood of damaging a top tier b&w film with one day in a hot car as miniscule. Of course I could be wrong; only an actual test would prove the case.

 

[Don_ih]

You should keep in mind, too, that there's a great deal of difference in levels of individual experience. Some may already have enough "real world" experience that they can automatically dismiss this as very unlikely.

Thanks for your detailed description of your testing. I doubt the interior of my van got anywhere near 60 degrees Celsius - but it did get about as hot as it ever will, here.

I wasn't dismissing the real-world experience of individuals. What I was dismissing was the attitude that a lot of people have that, because they believe something (for whatever reason), someone else shouldn't bother to do a simple test. Of course many people have experience of leaving film in their car and not having any problem with the resulting photos - but how many of those people were even looking for problems? Higher uniform fog on b&w would print through easily enough. Real world experience tends to be incomplete for such reasons, and that's why people test specific things.

I am in the group that pretty much sees the likelihood of damaging a top tier b&w film with one day in a hot car as miniscule

That's where I've been all along. But I've been surprised before, so I thought a simple test was easy enough.

what kind of film do you use that's numbered up to 40 (your top strip). Or is that a bulk-load? I don't know how bulk-load is numbered.

That was HP5+ from a bulk roll - both strips are.

 

[Henning Serger]

Could a 400 speed film like HP5 be heat fogged that quickly?

Very, very unlikely.
Here in Germany we have a very famous travel photographer - Michael Martin - who is specialised on photography in deserts. He travelled through all deserts in the world over the decades, and he has been for weeks in the desert zones. Almost always with motor-bikes. And the films in the bike-cases, for several weeks.
He reported that he never ever had any problems with heat affecting the films (he mostly used Velvia 50, Provia 100 and 400).

Best regards,
Henning

 

[Don_ih]

Second test complete. Two full days in the van. Partway through, I checked the temperature. It was 43 degrees at the cup holder and 49 degrees in the glove compartment - so I put the film in there.

Water spots on the film, since I didn't bother with photoflo. There's no real difference except the strip that was in the car might be slightly more dense. It
doesn't seem to be as visible on my phone photo as it is in reality. If so, though, it's not enough to make a significant difference.

The strip that was in the car is top.

The box from the strip in the car would undoubtedly look better as a scan, but you can see there's nothing really unusual-looking about it:

 

[Sidd]

I did the test, almost 50 years ago. Travelled mid summer from Europe overland to India and Nepal. Had about 50 rolls of Ektachrome 35mm and around 60 rolls black and white 120, Tri-x and Plus-x. The films stayed in van most of the time, or in non ac hotelrooms. After six months of travel, partly during the rainy season,
the films were developed and came out as expected: perfect!
we did not worry about such things in those days.

Films and cameras are actually much more sturdy for heat exposures than anticipated, otherwise we in Indian plains would never be able to shoot, especially in summers when the temperature easily rise above 40 degrees Celsius.