There’s a hack for that: Simply point your fingernail (or any object) against the glass; if there’s a gap, it’s a one-way mirror. If there’s no gap, it’s a two-way (and you should ...

He tried the DIY route for the two-way mirror, but decided to just order a glass one after some difficulty with bubbles and scratches. A smart mirror needs an interface, but unless you own stock ...

some were actually two-way mirrors. While Welles and Rita Hayworth acted on the reflective side of the glass, the camera could shoot everything from the non-reflective side without being detected.