Or do I have to find actual tinfoil?
That depends at room temperature, and at average 'on top of the head' temperature ( between 60F - 100F ) both metals are good electrical conductors (Aluminum is somewhat better)so either would be a good RF receiveras pointed out, you need to also concern yourself with the ground in RF applications if the temperature drops, (below about 50F) relatively pure tin will degradeIf not reheated to stop this processor if it gets really cold (sub-zeromaybe -30C)then you have to worry about tin pest where the tin totally crumbles awayThere is a legend that Napoleon's (soldiers'?) uniform buttons all rotted away, making them more susceptible to the cold on his ill-fated march toward MoscowOf course, if on the other hand, you are looking at bio-acoustic properties, Tin is known as the best and most tonally resonant metal [2 links from Wiki to Google Books] Therefore, a tin device could be much better at deflecting, or altering the properties of any acoustic waves directed at you [ I don't know that tin retains this best quality outside of (a) pipe organ production, and (b) sound frequencies we can hearlike pipe organs would use Sub-sonic ULF or supersonic frequencies , wellYMMV.] So, without more specific detail about the mind-control method (RF, acoustic, other.) AND about the way you intend to use the metal (Faraday cage, radio antenna, shaped helmet.) , I really can't be sure.
