How To Detect A Two Way Mirror [Fingernail Test]

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hi this is James at optical mirror today

I'm going to teach you how to detect a

two-way mirror a regular mirror can be

seen here and you'll notice there's

something called the fingernail test

which is when you take your Fingal

fingernail and hold it against the

surface of a mirror like so and if you

see a gap between your finger and its

reflection that means it's a standard

mirror then that's only a half-truth

because there are many different types

of two-way mirrors on the market the

mirror that won't pass the fingernail

test is actually the most common two in

there on the market which is called

mural painting or transparent mirror and

it comes in a glass so if you put your

finger against the glass - in here

you'll see your finger is touching its

reflection so that's a surefire way to

know that a mirror is without a doubt a

two-way mirror however there are

different types of mirrors on the market

the most notable being in acrylic so in

any sort of retail setting or commercial

setting this is incredibly common to

find now one side if it's installed

backwards the mirror side will be on the

surface and when you touch your

fingernail to it it will fail the

fingernail test but you flip that mirror

around if it's installed properly then

there is literally no virtually no way

to tell if you hold your finger you'll

see that there is in fact a gap so it

passes the fingernail test but there's a

few different ways to figure out despite


whether it's a two-way mirror the first

way is simply knock on it

if you hear kind of an echo be sound

that means there's a likely a hollow

space behind it as opposed to if I put

my hand flat you'll hear what it sounds


the meters being fully supported sounds

more solid when it's not being supported

hear that it's a little bit of an echo

so that's the subway to tell but the

best way to tell simply take out your

cellphone turn on the flashlight of your

cellphone and hold it up to the mirror

hold it all the way up and if you can

see the light literally passing through

to the other side as you can see there

but you should be able to see it from

the mirror side as well through the

mirror if you can see that that means

there's a hollow space and it's a

two-way mirror

for sure I'll take you through the final

type of two-way mirror as well just so

you're familiar with it a little less

common is a two-way here made with a

standard piece of glass combined with a

mirror film which you can see here and

from the mirror side it's gonna be

completely obvious it's film because

it's got all bubbles and scratches and

stuff but from the other side if you see

little bubbles behind the surface in

various areas that means it's a

transparent a mirror so that's yet

another way to tell if a mirror is a

two-way mirror or a standard mirror well

that takes you through it this is James

from optical mirror