How does one way bulletproof glass work?

Question

How does one way bulletproof glass work?

In: 541

Answer 1

Bullet proof glass is made with layers of hard but brittle glass and soft but flexible plastic.

The glass smashes and fragments the bullet spreading the force over a larger area to be caught by the plastic.

So if you shoot from the plastic side the bullet is able to focus its energy in a single point on the plastic and cut through it, hitting the glass intact and breaking it outward without the plastic to catch it afterwards.