Anyone use the iOS Magnetic Detector LITE app to screen for magnetism?

[dannyp]

So I was curious whether some of the small parts in my watches had become magnetized. I downloaded the Magnetic Detector LITE app and put the case back of my watches up to the phone in upper lefthand corner. The units of magnetism detected roughly doubled from what they registered when the phone was just sitting on my lap. Nowhere near as strong as when I put it up to my laptop, but not really sure how to read this thing...

Also much higher than when held up to a vintage watch recently back from full service (so likely demagnetized).

Went from, I think, about 47 micro Tesla to 88.

First question is whether this is a reliable tool? Second would be whether it's worth getting a cheap demagnetizer?

The readings were about the same for both my 32xx and 22xx outfitted watches, so main movement components are magnetic-resistant, but seems there are others that aren't (and their magnetization could explain a sudden but relatively small loss in accuracy).

[Old Expat Beast]

I never use my phone to check if my watch is magnetized...in case it magnetizes my watch, if that makes sense. I use a $10 map compass to check and a $10 demagnetizer, which has saved me hundreds of $ over the years. It's even got a couple of vintage watches running that arrived dead in the mail having been badly magnetized (I presume) by scanners.

[dannyp]

Originally Posted by Old Expat Beast

I never use my phone to check if my watch is magnetized...in case it magnetizes my watch, if that makes sense. I use a $10 map compass to check and a $10 demagnetizer, which has saved me hundreds of $ over the years. It's even got a couple of vintage watches running that arrived dead in the mail having been badly magnetized (I presume) by scanners.

Yea, but I figured that if I magnetized it further with the phone the demagnetizer would handle.

Is it possible to further magnetize a watch if demagnetizer used wrong/if watch isn’t truly magnetized? And can it be used with the watch running or just it be hacked (have heard both)?

[Old Expat Beast]

Originally Posted by dannyp

Yea, but I figured that if I magnetized it further with the phone the demagnetizer would handle.

Is it possible to further magnetize a watch if demagnetizer used wrong/if watch isn’t truly magnetized? And can it be used with the watch running or just it be hacked (have heard both)?

I've never had a problem with mine. I use it when the watch is running but not fully would.

[padi56]

Never had a problem with any of my watches due to magnesium,working with powerful electro magnets capable of lifting 50 tons,and working in the control center that puts out quite a strong magnetic field.Plus working with powerful radio amplifiers and transceivers again never had a problem.So dont need apps to test magnetises, or timing apps timegraphers or any of todays Rolex toys. And in general if the movement gets magnetised they mostly speed up and run very erratic and not slow down.