Privacy Monitor Hacked From an Old LCD Monitor




About: I'm an electrical engineer interested in making stuff!

Finally you can do something with that old LCD monitor you have in the garage.
You can turn it into a privacy monitor! It looks all white to everybody except you, because you are wearing "magic" glasses!
All you really have tohave is a pair of old glasses, x-acto knife or a box cutter and some solvent (paint thinner)

Here is what I used:
an LCD monitor of course
single use 3D glasses from the movie theater (old sunglasses are just fine)
paint thinner (or some other solvent such as toluene, turpentine, acetone, methyl acetate, ethyl acetate etc)
box cutter (and CNC laser cutter :) but that you don't really need, I'm sure x-acto knife and a steady hand would do just fine)
screwdriver or a drill
paper towels

Step 1: Take the Monitor Apart

Find an old monitor that you are willing to sacrifice.
Take off the plastic frame by unscrewing all screws from the back.

Step 2: Cut the Polarized Film

Most LCD monitors have two films on the glass - a polarized one to filter out the light you are not supposed to see, and a frosted anti-glare film. The anti-glare film we don't need, the polarized one we do - it is used for the glasses. 

So, grab you cutting tool and cut the films along the edge. Don't be afraid to press, metal wont scratch the glass, unless there is sand or other abrasives on it.

Then, start peeling. Make sure to save the polarized film, also remember the orientation.

Step 3: Clean the Film Adhesive

After you remove the film, the glue will likely remain stuck to the glass, so here comes the messy part.
With some solvent, soften the glue and wipe it off with paper towels.
I started with OOPS, but that was not fast enough so I got some paint thinner.
I found out that if you cover the screen with paper towels and then soak them in paint thinner you can let it sit longer and dissolve the adhesive without running and evaporating.
Scrape off the soft glue with a piece of plastic or wood.
Be careful not to get paint thinner on the plastic frame, because it will dissolve it.

Step 4: Monitor - Done

After cleaning the adhesive, assemble everything back the way it was. Before even making the glasses, you can test the monitor with the polarized film!
Notice how the upper left corner looks clear, because it has the anti-glare film removed. That is the part we are going to use to make the glasses.

Step 5: Pop the Lenses Out

For the glasses, I used single use 3D glasses from the movie theater, but you can use whatever you want.
Pop out the lenses or take the glasses apart if you can.

Step 6: Scan, Trace, Cut

If you are going to use a cnc blade or laser cutter, scan and trace the parts.
You can find a local vinyl or laser cutting service, or you could send them to an online service like
I scanned the frames so I can use them as a reference for the lens orientation.
Remember, this is a polarized film so the angle is critical. Back and front also matters.
If you don't have access to a cnc cutter or you don't want to wait for an online service, you can probably tape the old lenses on the film and then cut them out with an x-acto knife.

Step 7: Reassemble Glasses and Enjoy!

Finally assemble the glasses and you are ready for some fun!
People might think you are crazy, staring at a blank white screen wearing sunglasses!
But I guess that makes it even more fun!

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469 Discussions


1 year ago

I've removed the film from the monitor and cleaned all the glue. Now, when I look through the film from a distance, the image on the screen is vey blurred and I cannot tell what it is. Only when I put the film directly (closely) on the monitor it looks properly. Am I doing something wrong? I'm still waiting for the glasses but I'm concerned it won't work with them as it doesn't work now.

2 replies

Reply 8 months ago

Hi! Could you finally solved the issue about the fuzziness witht the screen and the film? I have the same problem

the rSantiagov36

Reply 7 months ago

There are two layers on that film: the anti glare and the polarized layer. They need to be separated (although I can't figure out how).

the r

Question 7 months ago on Step 7

Hello, I'm having some trouble separating the anti glare layer from the polarized layer. Do you have any suggestions?
Thank you in advance!


Question 10 months ago

So I have an HP Chromebook 11 G4, would this work on it? I'm getting tired of people looking over my shoulder to see what I'm working on...


1 year ago

Is there a way to make this screen look like it's off (ie black screen) to non-glasses wearers? A bright glaring white screen is a bit off-putting to onlookers,


3 years ago

I think this needs 1 more hack to be really useful.
We need to figure out a way to feature an image on the white screen that gets filtered out by the glasses.
For instance, if instead of a white screen, anybody without glasses who walked into your office would see a spreadsheet, but with the glasses you wouldn't see the spreadsheet.
Too complex, or is it a possibility?

12 replies

Reply 3 years ago

Print a full screenshot of the spreadsheet and taskbar onto a piece of thin, clear plastic. Convince people you can only see well with black and white, so you can make it a real high contrast print. But make sure any lines are thin. Apply this to the LCD, taking care to remove bubbles. Tehn jsut get uesd to seneig waht it looks lkie knid of srecwed up. The brain is amazing at adapting, and there is a good chance you read the last sentence naturally. Look again ^^.


Reply 3 years ago

XD do you read Cambridge research? If you raed any setcnene with the lteetrs gnoe arwy, tehn you can sltil raed it if the frist and lsat ltteres are in the smae palce as bofere.


Reply 3 years ago

Nveer raed Cabmidrge Rseaerch brefoe, but I saw tihs smoehwree and hvae uesd it to dmeontrstae my piont a few tmies.


Reply 2 years ago

Good at getting a 'Pinot' across...?/

Good-Oh! :D


Reply 1 year ago

Are you guys takling 'buot wine?


Reply 3 years ago

I know that but you cant read this:

sw y cy pe on ts we.


Reply 3 years ago

Full words please. Then I will translate it.

The brightness would have to be kept low as well to avoid drowning out the image of the spreadsheet with light.

Di ImmortalesChrisM371

Reply 3 years ago

That is a great idea, although i don't believe it can be done. You could maybe put a standing image, but then that would conflict with the image on the screen


Reply 3 years ago

Won't work. The crystals in a Liquid Crystal Display polarize the light to one direction or another, depending on their orientation, but doesn't actually block light. But when that polarized light shines through a polarized light filter (the film or glasses), it shows black or white depending on the orientation of the crystals or the filters. Without the polarized filter it's not possible for any image to be seen. The film he removed is a polarized light filter. So basically, he transferred the function it does from the screen, to the glasses. No matter were you place the filter, it will still polarize the light.


2 years ago

Would taking out the polarising film interfere with the touch screen function of an smartphone?