[cperciva]

Huh. I know lime plaster can contain significant levels of iron impurities, but I think even in the worst case those would be low enough to have an insignificant effect. Now I'm really curious too.

[scrps]

This is an interesting read:

https://blog.ibwave.com/a-closer-look-at-attenuation-across-...

I am tempted to disolve a bit of the plaster and run a conductivity test on it for fun. It is like living in a leaky faraday cage.