B&W film, ISO and airport x-ray scanners

[kiss-o-matic]

Jumping in here late:
My experience is in the US, getting a hand check is super easy although sometimes requires patience. TSA is a lot of things but on this, they deliver.

Europe is a whole other story.
Heathrow: They would not, no matter how much I begged, do a hand check as my film was not 800 or higher. I tried to explain that I push to 1600 (it was Tri-X) but they wouldn't budge.
London City Airport: they were delightful and did a hand check.
Berlin Brandenberg: Same as Heathrow. Didn't appear to be a CT scanner despite being a brand spanking new airport.

I've read some blog posts that say to get a film bag (eg, lead) so they're forced to hand check. I'm curious in actuality how well that works. Any reports?

 

[BrianShaw]

Jumping in here late:
My experience is in the US, getting a hand check is super easy although sometimes requires patience. TSA is a lot of things but on this, they deliver.

Europe is a whole other story.
Heathrow: They would not, no matter how much I begged, do a hand check as my film was not 800 or higher. I tried to explain that I push to 1600 (it was Tri-X) but they wouldn't budge.
London City Airport: they were delightful and did a hand check.
Berlin Brandenberg: Same as Heathrow. Didn't appear to be a CT scanner despite being a brand spanking new airport.

I've read some blog posts that say to get a film bag (eg, lead) so they're forced to hand check. I'm curious in actuality how well that works. Any reports?

I had similar experiences at Heathrow over the years.

Last time I used a lead bag was decades ago. More than one decade. When the bag showed up as an impenetrable object the screener pulled me aside, explained, opened the bag and placed my film in a tray, and put it through the x-ray machine again. I read recent recommendations to use a lead bad with amusement. I doubt they help get a hand check any faster than film in a clear plastic bag and a polite request.

 

[AgX]

I read recent recommendations to use a lead bad with amusement. I doubt they help get a hand check any faster than film in a clear plastic bag and a polite request.

But they can be a means against accidential X-raying. So one has to decide whether in ones case they are helpful, or rather attract attention and are a annoyance at security personnel.

One approach could be to keep the films in a lead bag until it has been established which kind of imaging device or which kind of inspection will be applied.

 

[Agulliver]

Do you know if Heathrow are using the new CT scanners for cabin bags?

I have a letter from the Department for Transport stating that all UK civil airports have been instructed to accept requests to hand check photographic materials. The DfT are aware of the concerns of Kodak and Ilford and have taken their advice.

the "under 800ISO" thing was for the old standard X-ray scanners. I can understand declining a request if they're still using those....though technically it does go against what the DfT has mandated.

The lead bags are honestly not worth it. They just arouse suspicion as they show up as an impenetrable mass. They have not been recommended in UK/Europe since at least the 1980s for this reason.

 

[guangong]

While I shoot film almost exclusively, for travel to Europe I would go digital.

 

[koraks]

They just arouse suspicion as they show up as an impenetrable mass.

I think on today's CT scanners they are fairly transparent. You don't even have to remove your film from the bag; they can destroy it while it's in there - convenient!

 

[BrianShaw]

I think on today's CT scanners they are fairly transparent. You don't even have to remove your film from the bag; they can destroy it while it's in there - convenient!

I’ve not read this before.

Do you THINK this, BELIEVE this, or KNOW it to be true?

 

[koraks]

Think & believe (after all, I did say "think" in the quoted post, for a reason!), based on the notion that these CT scanners easily scan through compound metal assemblies such as devices holding batteries etc. While lead is more effective at blocking xrays than lighter materials, a lead bag is only rather thin and won't have significantly more blocking power than a suitcase stuffed with clothes, laptops, cameras etc. A filled suitcase is easily a foot thick; the lead lining of one of those bags is a fraction of an inch. Keep in mind what blocks xrays is mass and it doesn't really matter how thick or thin you spread it out. If your typical lead bag weighs let's say 5 lbs (which is generous) and a suitcase weighs 10lbs, film packed in the center of the suitcase will be protected to the same extent as film in the lead bag (outside the suitcase).

If you read back we do have someone with lab experience, you might ask them for verification. If I'm dead wrong, I'd be happily corrected, although it would bring the question why lead bags aren't commonplace. They weren't in the heydays of film, even though multiple consecutive passes of film through regular onboard x-ray scanners did affect it and storage hold scanners evidently scan film right into oblivion. If lead bags had been very effective, you'd expect pretty much every self-respecting photographer to have one, and many of those having been handed over to the current generation of film shooters through estate sales & the second hand market in general. Oddly, this hasn't happened....

 

[GregY]

Anyone else have some real life airport experience in the last 6 mo to 1 yr ?

 

[BrianShaw]

Think & believe (after all, I did say "think" in the quoted post, for a reason!), based on the notion that these CT scanners easily scan through compound metal assemblies such as devices holding batteries etc. While lead is more effective at blocking xrays than lighter materials, a lead bag is only rather thin and won't have significantly more blocking power than a suitcase stuffed with clothes, laptops, cameras etc. A filled suitcase is easily a foot thick; the lead lining of one of those bags is a fraction of an inch. Keep in mind what blocks xrays is mass and it doesn't really matter how thick or thin you spread it out. If your typical lead bag weighs let's say 5 lbs (which is generous) and a suitcase weighs 10lbs, film packed in the center of the suitcase will be protected to the same extent as film in the lead bag (outside the suitcase).

If you read back we do have someone with lab experience, you might ask them for verification. If I'm dead wrong, I'd be happily corrected, although it would bring the question why lead bags aren't commonplace. They weren't in the heydays of film, even though multiple consecutive passes of film through regular onboard x-ray scanners did affect it and storage hold scanners evidently scan film right into oblivion. If lead bags had been very effective, you'd expect pretty much every self-respecting photographer to have one, and many of those having been handed over to the current generation of film shooters through estate sales & the second hand market in general. Oddly, this hasn't happened....

I’m inclined to agree with your thought/belief and thank you for verifying that you’ve seen no concrete information about the effectiveness of lead film bags against CT. There are vague statements in Kodak information sheets and Domke sales blurbs for their product that tend to agree and I’m always surprised that nobody has tested it. They write of “higher-power x-ray”, obviously referring to CT without being technology specific. Seems to me that testing and actually collecting some evidence would be easy and affordable to perform.

My lead bags, unused since the early 1990’s, are still in my photography junk drawer.

 

[pentaxuser]

Anyone else have some real life airport experience in the last 6 mo to 1 yr ?

Well said. I just don't see the point of reciting old bad experiences when we have seen what Agulliver had to say about recent changes and recommendations from the U.K. Transport Dept . What's key now is very current experiences either in terms of getting hand inspections in the U.K. or Europe or as appears to be the case in my post very recent users of Edinburgh and Berlin stating that the scanners there caused no damage.

Now in neither of the two airports I mentioned can I confirm that new CT scanners are used but certainly at Edinburgh there was lot of circumstantial evidence that it has moved to the new ones

It is very recent experiences that count, isn't it

pentaxuser

 

[cowanw]

Anyone else have some real life airport experience in the last 6 mo to 1 yr ?

I will cross post this from another similar thread.
I have had three trips from Canada to Europe this year and can report my n of two study. I put two rolls of film through the CT scans at Amsterdam; one new XP2 and an old out of date but frozen Kodak BW400CN. Neither roll showed any negative effect from the CT scan machine.
The Iceland airport has only x-ray machines as does Toronto Terminal 3, Frankfurt Terminal 2, and Copenhagen Terminal 3.
All of the terminals were very kind about hand inspection.

 

[BrianShaw]

It is very recent experiences that count, isn't it

Yes, indeed. Rehashing old experiences aren’t particularly useful because the don’t necessarily transfer to the newer technology. But those recent experience reports need to be based on knowledge. While some recent reports seem well informed, others may not be. Part of this discussion broaches topics where the community has knowledge gaps - like where the CT machines have been deployed, which type of machine was recently experienced, and the capabilities/vulnerability of some potential countermeasures. There are many moving parts to this topic.

 

[AgX]

Think & believe (after all, I did say "think" in the quoted post, for a reason!), based on the notion that these CT scanners easily scan through compound metal assemblies such as devices holding batteries etc. While lead is more effective at blocking xrays than lighter materials, a lead bag is only rather thin and won't have significantly more blocking power than a suitcase stuffed with clothes, laptops, cameras etc. A filled suitcase is easily a foot thick; the lead lining of one of those bags is a fraction of an inch. Keep in mind what blocks xrays is mass and it doesn't really matter how thick or thin you spread it out. If your typical lead bag weighs let's say 5 lbs (which is generous) and a suitcase weighs 10lbs, film packed in the center of the suitcase will be protected to the same extent as film in the lead bag (outside the suitcase).

If you read back we do have someone with lab experience, you might ask them for verification. If I'm dead wrong, I'd be happily corrected, although it would bring the question why lead bags aren't commonplace. They weren't in the heydays of film, even though multiple consecutive passes of film through regular onboard x-ray scanners did affect it and storage hold scanners evidently scan film right into oblivion. If lead bags had been very effective, you'd expect pretty much every self-respecting photographer to have one, and many of those having been handed over to the current generation of film shooters through estate sales & the second hand market in general. Oddly, this hasn't happened....

You are completely wrong... as you say that X-ray opacity is just dependend on the absolute Mass located anywhere on the imaging path.


Instead of absolute Mass it is about Density !

Thus it is about Material !




X-Ray opacity is proportional to

-) the Density

-) 3rd power of the Atomic Number

-) Thickness

 

[koraks]

X-Ray opacity is proportional to

-) the Density

-) 3rd power of the Atomic Number

-) Thickness

Density + thickness = absolute mass.
Density and atomic number overlap to an extent in this application; considering both separately AFAIK would not be sensible. Instead, it would be more sensible to consider the actual mass attenuation coefficient.
So technically your statement is likewise inaccurate. Or, as you put it, "completely wrong".

While my earlier statement may not be correct in an absolute sense, the principle does hold. You can argue though if it takes a stack of 6 neatly ironed cotton shirts to equate the same attenuation of a lead bag, or the stack of 6 shirts plus the woolen sweater aunt Edna knitted for you last Christmas. I'll grant you that uncertainty and confess my prior claim does not account for this element of wardrobe uncertainty.

 

[AgX]

Density + thickness = absolute mass.

But that is not what you wrote...

You stated that material does not matter, but mass.
You had it about same masses of different materials spread arbitrarily over waylength. And this is not density but is about absolute mass per waylength.


But as I said above for X-ray opacity density matters, it is dependent on material.

 

[AgX]

Of course one may enlarge waylength for a less opaque material up to a point where it yields same absorbtion as e.g. lead.
But this is completely different from same masses of different materials somehow located in the waylength as you said.

 

[koraks]

But that is not what you wrote...

Apparently it is not what you think I wrote.

Of course one may enlarge waylength for a less opaque material up to a point where it yields same absorbtion as e.g. lead.

Which is what I actually wrote:

If your typical lead bag weighs let's say 5 lbs (which is generous) and a suitcase weighs 10lbs, film packed in the center of the suitcase will be protected to the same extent as film in the lead bag (outside the suitcase).

We can bicker over the 5lbs vs. 10lbs; I picked double the mass for the less dense material just to clarify my point. So the suitcase with clothes in my example is double the mass spread out over a larger (unspecified) distance (due to the lower density of the suitcase) than the lead bag.

But this is completely different from same masses of different materials somehow located in the waylength as you said.

Which is not what I said, if you read back carefully.

I hope I somehow clarified what I wrote earlier; as far as I'm concerned my language wasn't unnecessarily diffuse or difficult to understand, but somehow you managed to not really get it, I'm afraid.

 

[AgX]

You explicetedly said that a suitcase yields the same X-ray absorbtion as a foil of lead if the suitcase got the same mass as the foil of lead.

And this is wong. What matters is not mass as such, but it is material density. Thus you cannot compare a foil of lead to a suitcase, by the mass they bring into the path of the rays.

Your wording:
"A filled suitcase is easily a foot thick; the lead lining of one of those bags is a fraction of an inch. Keep in mind what blocks xrays is mass and it doesn't really matter how thick or thin you spread it out. If your typical lead bag weighs let's say 5 lbs (which is generous) and a suitcase weighs 10lbs, film packed in the center of the suitcase will be protected to the same extent as film in the lead bag (outside the suitcase)."


As I already stated above you may yield similar X-ray opacity with different materials if you pack enough of the respective material in the X-ray path, but this is a different approach, not based on mass as yours.

 

[BrianShaw]

How thick is Aunt Edna's woolen sweater?

 

[Craig]

Anyone else have some real life airport experience in the last 6 mo to 1 yr ?

I went through Heathrow T3 in May and my films look fine to me. Clear edges that look the same to my eye as films bought locally and processed at home.

 

[GregY]

I think it's worth repeating that even before the new scanners there were occasions where film was damaged by x-rays or repeated exposure to x-ray machines.

 

[koraks]

You explicetedly said that a suitcase yields the same X-ray absorbtion as a foil of lead if the suitcase got the same mass as the foil of lead.

And you then proceed to quote my post where I very literally don't say this.

I'm going to leave it at this, as the diatribe you're making doesn't add anything to the premise of this thread, nor to my argument about the usefulness of lead bags. The only thing I'll say about the matter is that I disagree with your misconstruction of my words.

 

[pentaxuser]

Well my tentative conclusion is that there may be growing evidence that (a) European airports' security staff are becoming more amenable to doing hand inspections which is great and (b) there may be evidence that CT scanners may not be as bad as the apparent science on CT scanners leads us to believe

We need more experiences from users at CT scanner -equipped airports of course

pentaxuser

 

[Agulliver]

I think it's worth repeating that even before the new scanners there were occasions where film was damaged by x-rays or repeated exposure to x-ray machines.

Films were damaged by exposure to the CT x-ray scanners used to scan checked (hold) baggage. Films could be run through hand baggage scanners using conventinal x-ray scanners (non-CT) many times without measurable or noticeable damage.

The new hand baggage scanners use CT scanning which is much more likely to damage film than the older hand baggage scanners.

My recent experience is two sets of flights between London Luton and Lanzarote in Feb and March 2022. Both airports still use the older x-ray scanners and at Lanzarote they were even labelled "film safe".

I'm booked to go from LHR-DFW-XNA and back XNA-ORD-LHR next month and will report my findings.