Night Ops

Does anyone have ever heard of magnetic field viewer film ?
It basically a thin piece of plastic of around 2 inches by 2 inches, it's flexible and it allows you to view magnetic fields even if they are behind surfaces (not too far away).
I thought this might be interesting to try it on a magnetic door alarm, it would be much quicker than the compass method.
I think I'll buy it to test its capabilities.
If you guys have ever tried it, let me know how well it performs

PS : Sorry for my bad English

First time I've heard of it. Where do you even get it? They don't seem to stock it at my local Walmart.

I think you can get it only from Ebay, there is actually some good Chinese suppliers of this thing on Ebay, so you can get it for less than 9 bucks a sheet, I think.
It's not super cheap but still it seems to be great. If you go on Youtube, I'm sure you can find demos of it working

Here's a good demonstration (as far as I've seen).

https://www.youtube.com/watch?v=slVL5nbTXd4

First concern would be practicality. For detecting magnetic switches, or any smaller magnets around entrances, a compass would seem more practical - it's easier to see and read off.
But for each purpose it's own tool, I suppose magnetic viewer film would be really handy in some situation. I wouldn't carry it on me regularly though.

Yeah, I'd say a compass would be more practical for magnetic door alarms. Still, neat bit of kit to have around for other applications.

Thank you guys for your replies

Looks like a neat thing, but from the video it seems like it might not be sensitive enough to detect magnetic door alarms, not to mention the fact that it'd be fairly harder to see one on this thing in the dark than on a compass (unless you can convince them to coat the little bits of metal with fluorescent paint, but that still leaves the sensitivity issue).

Some compasses have tritium markings on them too, allowing you to read them in pitch black without a light source.

Wow I didn't know that kind of compass exist !
That's interesting