X-ray machine sends out X-rays are able to penetrate a lot of items, in addition to the material density of objects can not be penetrated, generally metal such as iron, copper, gold, silver, and mixed objects: barium sulfate.
But now the security machine kv is very high, are in the 150 or more, the general iron bottles penetrate a little problem, unless the use of lead. Lead is black under the x-ray. But lead is bound to trigger an automatic alarm on the machine.