Different fog+base levels in HP5+, why?

argent_negre · Jun 20, 2025

Hello to everybody.

I have recently developed 4 rolls of HP5+ in the same tank (i.e., same developer, time, agitation, etc.) and one and only
one of them has a higher level of fog+base than the others. See the attached picture. I would like to understand why
this happened.

I am quite sure the rolls were not expired and that they may have the same expiry date (2027).

The only difference is that the roll with the highest fog+base level has made an additional travel by plane. Let me summarize:

- one roll hasn't traveled by plane (shot with a Rollei 35)
- three of them have been in Kyoto (BCN-Abu Dhabi+Osaka and back) (shot with a Leica)
- one of them (the fogged one) has and additional travel (BCN-Schipol-Beijing and back) (shot with the same Rollei 35).

So my question is: can x-ray fogging be the cause? As you can see, it is uniform along the whole roll. I have always thought
that x-ray fogging produces wavy patterns on film.

In the past I've had cases of high base+fog rolls, but I had always thought that the reason was that they had been in
the camera for too long (sometimes years). I'm sure this is not the case.

Any suggestions?

I have one roll that came with me to China and I don't know if I should use it normally or reserve it for experiments.

koraks · Jun 20, 2025

argent_negre said:
So my question is: can x-ray fogging be the cause?

Definitely. You've got a case of CT fog.

argent_negre said:
I have always thought
that x-ray fogging produces wavy patterns on film

That's the case with the regular/old fashioned x-ray inspection machines, which virtually never result in noticeable problems anyway. But CT scans result in significant amounts of overall fog, exactly what you're seeing on your film.

Especially when going through CT scans with your film, request a manual check! This is virtually always granted in Western countries.

argent_negre · Jun 20, 2025

koraks said:
Definitely. You've got a case of CT fog.

That's the case with the regular/old fashioned x-ray inspection machines, which virtually never result in noticeable problems anyway. But CT scans result in significant amounts of overall fog, exactly what you're seeing on your film.

Especially when going through CT scans with your film, request a manual check! This is virtually always granted in Western countries.

I'am afraid it was at Schipol, where I explicitly asked if the machine was safe (it looked to me it was a CT scanner) and the guy there say it was. In Rome-Fiumicino they have a separate line for film and in Osaka they do manual inspection.

Does anyone have experience how to get manual check in Schipol?

retina_restoration · Jun 20, 2025

koraks said:
Definitely. You've got a case of CT fog.

That's the case with the regular/old fashioned x-ray inspection machines, which virtually never result in noticeable problems anyway. But CT scans result in significant amounts of overall fog, exactly what you're seeing on your film.

Especially when going through CT scans with your film, request a manual check! This is virtually always granted in Western countries.

Exactly. It’s radiation fogging.
It’s in your best interest to request hand inspection, not allowing any film - especially fast ones - to be exposed to airport scanning equipment. There are no ”safe” scanners.
That said, the fogging you see on your negatives isn’t severe enough to impede your ability to get good images from that film.

argent_negre · Jun 20, 2025

retina_restoration said:
That said, the fogging you see on your negatives isn’t severe enough to impede your ability to get good images from that film.

You are right. I am more concerned about the two additional unexposed rolls that went through the same machine.

koraks · Jun 20, 2025

argent_negre said:
I'am afraid it was at Schipol, where I explicitly asked if the machine was safe (it looked to me it was a CT scanner) and the guy there say it was.

That's an unfortunate miscommunication or misinformation by the security personnel. Schiphol does indeed have the newer CT machines and they will demonstrably damage film the way you've experienced. However, people traveling so far through that airport have all received a manual check if they asked for it.

Did you ask if the machine was 'safe', or did you specifically ask for your film to be hand-checked? I'd suggest the latter; the former may just trigger second-guessed nonsense answers from security guards who really don't know about film.

Also, whenever possible, try to avoid that particular airport. It sucks in pretty much every way.

argent_negre · Jun 20, 2025

koraks said:
Did you ask if the machine was 'safe', or did you specifically ask for your film to be hand-checked?

I probably asked only if it was safe, without any request, but I had already the rolls of film and the camera in my hands. Very unfortunate.

koraks · Jun 20, 2025

Yes, indeed. Of course, the security staff should have been more forthcoming/alert and offered you a hand check...but then again, I think we shouldn't expect too much of them either, especially since the typical workload they face. The quicker the stream of passengers goes through, the better, and such subtleties as fogged camera film is something they won't even stop to think about provided they're aware of the phenomenon to begin with.

In my experience, what generally works is a little bit of persistence and a generous bit of politeness and friendliness. So far this has gotten me through CT with hand check 100% of the time and around 90% of the time on general x-ray lines.

albireo · Jun 20, 2025

@koraks can I ask, what do you mean by hand check? I've only flown with film a handful of times over the past year across Europe, but in no case I got a hand check. What I got was an 'alternative check': the employee would grab my ziplock bag with the rolls and hand it in to a different colleague who then scanned the rolls through a separate, 'film safe' scanner (similar to the old style ones) while in parallel the rest of my baggage went through the standard CT scan procedure.

koraks · Jun 20, 2025

By hand check I mean they visually inspect the bag with film rolls (generally cursory) and then usually swab it to test for (I assume) explosives. I've not seen my film get scanned in a parallel stream using different technology, but I'm not surprised that this happens. I've just not had it happen to my own film yet.

ArnoG · Jun 23, 2025

I fly a lot had the same experience with Fomapan 400, wondering about QA at the factory due to varying levels of fog until I realized that, indeed, the difference was the amount of flying with the films. I have them in an old school lead bag but even with that and old school scanners I see an increase in fog. Schiphol always allows for hand checks (for me) but the Airport in Toulouse simply refuses. The increased fog reduces the dynamic range that can be achieved significantly so it’s frustrating. I always ask for hand checks but unfortunately it is not always granted. The lead bag should help but it’s not perfect.

Agulliver · Jun 23, 2025

Yep looks like that roll got zapped by the CT scanner. It's damaged but you should still be able to scan or print photos from it.

The best thing to do is to explicitly request a hand inspection of your film. These days I travel with all my film in a ziploc type bag, for convenience. I get it out at the security line and wave it about, asking if I can have a hand inspection. On one occasion recently I was told I didn't need to put liquids through separately and I explained quickly, "It's photo film. I think that's a CT scanner which will damage it" and the security guy immediately realised he'd mistaken my bag of mostly yellow boxes for liquids. Perhaps that's what happened when OP asked if the scanner was "safe".

koraks · Jun 23, 2025

ArnoG said:
I have them in an old school lead bag but even with that and old school scanners I see an increase in fog. Schiphol always allows for hand checks (for me) but the Airport in Toulouse simply refuses.

A lead bag will not be adequate to protect 400-speed film from CT fog. The Bessanova/ADOX test demonstrated this.
Does Toulouse have the CT scanners? It would be the first time I hear about a western airport equipped with CT scanners to refuse a hand check.

Welcome to Photrio btw!

Saganich · Jun 23, 2025

For a typical CT at 120 keV the tenth value layer of actual lead is 0.8mm. I fogged a roll on purpose a few months ago at JFK just to see what it looks like...and that's what it looks like.

Dr. no · Jun 23, 2025

argent_negre said:
Does anyone have experience how to get manual check in Schipol?

albireo said:
hand it in to a different colleague who then scanned the rolls through a separate, 'film safe' scanner

I've never had them take it to a different XR machine.

In April I just handed my two bags of film (pictures of tulips and windmills, of course) to the attendant and they whisked it over for sniffing (yes, its a mass spectrometer/gas chromatograph and looks for explosives/incendiaries, not drugs).
The thing about traveling with film is that you have to pay attention, they won't warn you or protect you, and, in my experience most machines have no warning signs on them (a few do). If it's a CT scanner I always ask and have never been denied. If it's regular XR machine and in a hurry I might skip that, but if I ask they will hand check. Some people say they keep a roll of high-speed film in their cache as an excuse.
Regular machines are a risk too, but it takes several passes to see significant effect (usually...).

This is being discussed ad nauseam here: https://www.photrio.com/forum/threads/new-as-of-2019-airport-ct-scanners.170709

albireo · Jun 24, 2025

Dr. no said:
I've never had them take it to a different XR machine.

Yeah interesting seems like there's really no standard rule about this. My experience was about continental Europe.

In a number of airports using the new CT scanners that I've visited (example: the new, and otherwise awful, Berlin Brandenburg airport) the CT is scanner is clearly market 'NOT FILM SAFE' with an image of a camera crossed with an X.

As you place your baggage on the conveyor belt for inspection, you show the employee your clear bag with film and they'll hand it over to another colleague beyond the CT scan checkpoint who will run it through what looks to me to be an old style X-ray scanner and hand it back to you once you're through.

I've never had to do anything special so far: no relabelling, no begging, no hiding film in my tooth capsules. Just a very smooth process. In a couple of occasions, in Italy and Spain, I struck a conversation with the security employees who were clearly old-time film enthusiasts and were entirely sympathetic and happy to help.

dcy · Jun 25, 2025

koraks said:
Especially when going through CT scans with your film, request a manual check! This is virtually always granted in Western countries.

That is good to know. I had read on Reddit that in various European countries they just ignore you and put it on the CT anyway. I personally haven't yet had a chance to test this; I moved out of Europe prior to getting interested in film.

koraks said:
Did you ask if the machine was 'safe', or did you specifically ask for your film to be hand-checked? I'd suggest the latter; the former may just trigger second-guessed nonsense answers from security guards who really don't know about film.

Absolutely. A little while back I saw a sign at an airport that said that the X-ray machines are safe for film below ISO 800.

Here's an anecdote from a YouTuber who was flying with sheet film: He asked for a manual check. While he was on the line for the scanner, he saw the TSA agent inspect the film, write a little note saying it was inspected, and proceed to open the light-sealed box, followed by the light-sealed bag that contained the film to slip the note inside. Then then YouTuber finally got to the front and said "dude, you ruined my film" the TSA agent goes "oh, don't worry, I was very quick".

dcy · Jun 25, 2025

albireo said:
@koraks can I ask, what do you mean by hand check? I've only flown with film a handful of times over the past year across Europe, but in no case I got a hand check. What I got was an 'alternative check': the employee would grab my ziplock bag with the rolls and hand it in to a different colleague who then scanned the rolls through a separate, 'film safe' scanner (similar to the old style ones) while in parallel the rest of my baggage went through the standard CT scan procedure.

In my experience, if you ask for a hand check they visually inspect the package and sometimes they do that thing where they swipe around with a cloth and put the cloth in a machine that detects explosive material.

Saganich · Jun 25, 2025

albireo said:
As you place your baggage on the conveyor belt for inspection, you show the employee your clear bag with film and they'll hand it over to another colleague beyond the CT scan checkpoint who will run it through what looks to me to be an old style X-ray scanner and hand it back to you once you're through.

I had same experience at LGA terminal B I believe...I gave them film and they ran it through an old X-ray scanner on a different security line.

albireo · Jun 25, 2025

dcy said:
In my experience, if you ask for a hand check they visually inspect the package and sometimes they do that thing where they swipe around with a cloth and put the cloth in a machine that detects explosive material.

I tried - it didn't work - they insisted they'd have to scan the film, but using a safe device. Believe me. I travel a lot and not once they let me go with a hand check and an explosive detection swab. It must be airport-dependent. I've not flown through Schiphol with film for instance.

Agulliver · Jun 26, 2025

In recent years I've taken to flying with my films all in one ziploc type bag, which can be easily removed to wave at the security staff who are usually in the area where you collect a try for your bag. If they don't offer to hand inspect (which has happened), I say something like "Photo film, is your machine safe?". On my most recent trip a couple of months ago which took in London Heathrow, Helsinki, Kansai and Tokyo Narita they hand inspected at all the airports even where they had standard X-ray scanners. which is to say that they had a look at the film boxes, swabbed some or all for explosives and then sent me on my way with a smile.

I would not mind my film going through a "safe" regular X-ray scanner if that was another option. Helsinki was an interesting one as they had a look at and swabbed every individual box. I was also carrying film for my partner who was dealing with being in a wheelchair so didn't want the extra hassle of asking for film inspections...and had a very full freezer bag of 35mm, 120 and Polaroid films. The staff were thorough but pleasant throughout.

As with all airport security issues, I find that being polite and compliant helps. Any hint of attitude and they return it with extra interest.

What is encouraging is that more airport staff seem to be becoming aware of the CT scanning issue with film and know what to do. Some recognise 35mm film boxes too. Though I still get odd looks when my cabin bag is basically cameras and lenses...not the usual books, tablet, headphones, toothpaste, moisturiser etc.

dcy · Jun 26, 2025

Agulliver said:
I say something like "Photo film, is your machine safe?".

I never ask. Like @koraks said, if you ask, you invite them to say "yes, it's safe". What I say is "Hey! This is film. It cannot go through the machine. Could you inspect it by hand please?".

Different fog+base levels in HP5+, why?

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