I may have been snakeoiled (Patreon)

Back in the days ™ mu metal ( https://en.wikipedia.org/wiki/Mu-metal ) has been applied to oscilloscope display tubes so that their magnetic fields would not interfere with the sensitive circuitry. Mu metal is solderable, so I thought I'd solder a hermetically sealed and EMF proof enclosure for my LTZ1000A voltage reference. The power supply and voltage output could be fed through the hermetic barrier with hermetic feedthrough capacitors which have a glass-metal seal.

Mu metal is currently rising in popularity again, because the multicopter crowd likes to shield their flight controller IMUs against EMF from the motors and drivers. And it was wickedly expensive even before that ... Now I've bought some expensive, but not ludicrous 'Mumetall' from a German eBay seller without reading the fineprint: https://www.ebay.com/itm/172871273704

Oh btw guys, this is not really Mumetall, even though it says so in the title ;))))

They claim it's much better etc but it seems to be made for the electrosmog niche, so I am not sure if it's scientifically sound. I have tested only a small single layer section so far, which doesn't really allow for convenient closing of the field lines.

It'll probably perform better when shaped into a fully closed enclosure. I'll get some proper, thick mu metal next week and show some proper results then.

The snake oil foil has an interesting feel to it tho, it breaks rather than bending, which makes their 'amorphous cobalt alloy'-claim somewhat credible.