Has anyone received books with an interior wrap of aluminum foil?  My first ones came today.  Is foil considered to be waterproof?  I'm  accustomed to many other types of interior protection...plastic wrap, newspaper bags, sandwich baggies, storage bags...but this is a new one.  Foil??? 

Well, interesting but mostly because foil is very expensive.

There is no rule against foil.

And no rule that books must be mailed in a waterproof package. So whether or not foil is waterproof doesn't really matter.

I would guess it depends on how the foil is folded. If there is a long seam where one part of the foil is just laid over another part, it would not be waterproof. But if the foil is folded over onto itself, then it could be waterproof. I'll stick to plastic bags.

I've never gotten foil. More often I get cellophane.

  I think I got foil once.......my guess is the sender normally uses Saran wrap and ran out so used something else from their pantry.......I reuse CLEAN plastic so I save by not spending money on my interior waterproof wrapping.  We spend enough on packaging tape that we should look for other ways to save.

   And the packaging instructions do say they 'recommend' wrapping in plastic first before packaging.

My supermarket provides green plastic bags into which you place produce.  Once home and the produce is removed, I turn them inside out, let them dry out  and they become waterproof book wrappers for the smaller, lighter paperbacks.  These are large enough so I can fold them over the book two or three times without taping them. Hopefully, this allows the book requestor to reuse them. For heavier books I use the more durable, plastic, outer wrapping on bread loaves.

I have gotten foil once or twice. I agree with Jeanne and bet that that person probably ran out of what they normally use whether it be plastic bags or plastic wrap and want to get the book out with some type of added protection.