Hi there, looking for some expert/technical advice on light exposure in 4x5 film packs.

I have some leftover 4x5 sheet film (Ilford HP5, ISO 400, B&W) from a course whilst studying abroad. It costs a pretty penny so of course I wanted to take it home to the UK, as my home university have just bought a large format camera I could use the rest in.

I've just been through airport security with it for the first time. I know to never put film in checked luggage, remove it from your hand luggage and ask for a hand check because of the cumulative effect of x Rays.

The security person I asked for a hand check said it was fine to do a hand check on boxed film and knew what large format film was, the fact the bag can't be opened etc.

However, a different staff member did the actual check at the end of the line (Montreal YUL airport) and had no idea what she was dealing with. She opened the first lid, then removed the second cardboard 'lid' underneath, thus removing the bag from the box completely. The bag wasn't taped (I am aware this is my error) and so the 'flap' of the bag wasn't sealed and was hanging away from the bag a little at about a 45 degree angle. There is the usual 2 pieces of cardboard that covers the top and bottom of the film stack within the bag.

The security staff member said she would have to open the bag (even though I explained what her colleague had said) and so I said no, send it through the X day scanner.

I've read on various forums that ISO 400 B&W film should be okay with only one scan, but can be ruined, hence accepting the hand check.

However, I'm worried that the film with have been ruined with light exposure from the un-sealed bag during the hand check. I was under the impression that the bag is lightproof, so would only the edges perhaps be ruined? Or the whole surface of every piece? There's approximately 19 sheets of film left.