[Lord Lucan]

I don't think iron is used in modern films. I think it was used in some of the old plate processes in the beginning of photography.

Ferrotype and tintypes (same thing) used a thin steel base. The image was still silver based though. Some street and seaside photograpers were still using it in the 1970s because it had an on-the-spot development process and was cheaper than Polaroid.

[BigMackCam]

It seems like every time I ask a question or request help in these forums, I end up learning even more than I'd originally hoped! Interesting stuff, indeed... Thank you, all!

[Digitalis]

My only word of caution with the design would be that if there is any roughness in the magnet surface or abrasive dust and the mechanism (or person) pulls the magnet in a way that makes it slide across the film before lifting off, then it could scratch the emulsion or base layer. Neodymium/rare earth magnets can be beastly strong and hard to separate and tend to slide first.

I concur, also if there is any potential for the magnets to rub against each other with any debris on them it can mechanically damage their inert nickel plating which will allow oxygen in and cause the magnets surface to pit and corrode, and if they impact each other with enough force it is possible they will shatter completely. This is why modern packaging companies will often use a magnet on one side of a closure and use a ferromagnetic material on the opposing side, as they learned two strong magnets can be quite hazardous.

[Wheatfield]

Nope. Silver isn't magnetic and color film has no silver in it anyway by the time you get it back from the lab.

[TwoUptons]

As others have said, magnetic fields won't affect film.

My only word of caution with the design would be that if there is any roughness in the magnet surface or abrasive dust and the mechanism (or person) pulls the magnet in a way that makes it slide across the film before lifting off, then it could scratch the emulsion or base layer. Neodymium/rare earth magnets can be beastly strong and hard to separate and tend to slide first.

You might also take just a bit of care with iron and steel tidbits -- an errant staple that get sucked in and stuck to the magnet and then clamped to the film might not be pleasant.

I look forward to seeing BigMackCam Magno-Scan-O-Matic 3000 in operation!

I was thinking this is exactly how I would manage to mangle negatives with a magnet...
That or get one caught in the wrong place and have it attract to another one and bend the film over, crimping it...

-Eric

---------- Post added 04-25-22 at 02:24 PM ----------

I concur, also if there is any potential for the magnets to rub against each other with any debris on them it can mechanically damage their inert nickel plating which will allow oxygen in and cause the magnets surface to pit and corrode, and if they impact each other with enough force it is possible they will shatter completely. This is why modern packaging companies will often use a magnet on one side of a closure and use a ferromagnetic material on the opposing side, as they learned two strong magnets can be quite hazardous.

They've also learned it's far easier to made the thing that way, as they don't have to worry about polarity with a single magnet and a piece of ferrous material...

Otherwise they'd have some percentage of "why... won't... the... latch... close... at... all..." on their QA line

-Eric