anything but tinfoil or aluminum foil,
The problems with aluminum foil... I do not get... no problems if you do it right...
Like everything, there is a right way, and a wrong way to do something...
Hot spots really, I think this myth is over stated, maybe if you crumple it up on the walls...
Fukk, hang your cheap ass Tin Foil like wall papper... Use spray on contact cement like
Loctite Spray Adhesive
My walls are smooth aluminum foil...smooth... real smooth...over lapped aluminum foil...
Hot Spots...Really... not in my room,
Now if you want to argue {I don't] I am just pointing out, if you take your time, and hang it like you would if you were hanging wall paper, no one would get hot spots...
I want the heat to stay in my room, tin foil on plywood is fine, if you take your time and do it right...
Do any thing half assed and you'll have problems...
Now, if you want to talk about the dangers of aluminum foil:
http://www.bellaonline.com/articles/art7739.asp
That's a different story... I don't let plants hit the walls...
Tin Foil and hot spots I think are a myth started by a Newbie that burned the fukk out of his plants, and his bromance partner said:
"...wow dude, don't use that shit, it's no good..."