Show a Silk to the audience and use it to clean the mirror.
As you wipe the mirror the silk starts to penetrate the center of the glass.
Halfway through, the mirror can be turned around and shown on both sides with the Silk sticking out the opposite side!
Now face the mirror towards the audience once again and the silk is pulled through.
There are NO Visible holes!
The penetration takes place right before the eyes of the audience.
Both before and after the effect the audience sees a solid mirror, tap it with a wand.
