I would like to make one correction to a common misperception. Xrays damage undeveloped film. That's a fact. I don't care what the exposure is, all radiation capable of interacting with film emulsions damage it.
The question is simply how much do they damage it?
The tests that the FAA have done seem to support the notion that five or fewer passes through a standard carry-on xray machine of films with ISO speeds of less than 800 do not cause the type of damage that can be seen - my own experience as a former road warrior would tend to support that as well. The TSA recommends on their own website that if you have film of greater than ISO 800, you should request a hand-scan. If your film has already been exposed to xrays via airport security at least four previous times, request a hand-scan. You can also request a hand-scan 'just because' if you like.
For those who do not fly much in the USA, I can assure you that the TSA has a lot of leeway in how they enforce their own rules, and it varies widely from airport to airport, inspector to inspector. Some will honor your request to hand-scan and some will not. As someone else noted, a bad attitude displayed to the TSA will pretty much guarantee that you will not get your request granted.
This is my experience, and for seven years, I flew on domestic commercial airline flights at least twice a week, every week. That's thousands of flights logged, and millions of air miles. I respect everyone's opinion, but I think my experience trumps about everyone else's except maybe a fellow road warrior. I did stop flying about a year and a half ago, so I will accept that some things may have changed.
I would not advise carrying film on your person through the metal detectors. Their sensitivity varies, but most of them can and often do alert on the smallest of metal items in your pockets, and 35mm film cannisters are definitely in that range. Some are cranked up so high, I swear they detect the iron in your blood and the fillings in your teeth.
I would not advise using lead-lined bags for film. In checked luggage, they are worthless, as the high-energy (not xray) scanners used will 'see' right through the lead bag anyway, and your film will be destroyed. In carry-on luggage, the TSA recommends against it, because when they see a dark mass that they cannot 'see' through in their standard xray screening, they stop and remove it anyway. This takes time, slows up the process, and ensures that the TSA folks are not kindly disposed towards you, especially since the TSA website advises people NOT to use the lead-lined bags. They do say that the bags can be useful overseas, so if you have them or absolutely MUST buy them, I'd take them with me in my checked luggage and use them AFTER I got overseas. But frankly, in these days, hiding things from xray scanners is a really good way to get TSA inspectors interested in your body cavities, know what I mean?
The way I used to carry film was this - others have said the same thing in this thread - I used to take my 120 and 35mm film out of the cannisters and put them in a clear plastic baggie. Like Pherdinand, I also kept a 'sacrifice' roll of ISO 3200 film in the bag as well. So if asked "Do you have high-speed film?" I could always truthfully answer yes. Some TSA inspectors will refuse to hand-inspect unless you say you have high-speed film. I always asked very politely if they would hand-inspect my film. Always, that is, after I learned my lesson about insisting on my rights with those goons and how far that gets you these days. I walked funny for a week.
The 'polite' method did not always work - but it was the closest thing I had to something that more or less worked, and so I advise it.
If *I* have learned to button my lip in front of the TSA, you might reasonably suspect that stating that you are a professional photographer and insisting that your film be treated with respect is not really the best way to go about it.
All I have to offer is my experience dealing with the TSA - feel free to accept or reject it.
Best Regards,
Bill Mattocks