iMacs late 2012 onwards are a pain in the ass to service because of the glued down screen – easy to break during disassembly, or falling later during a hot day because of the adehesive melting. Still, the LCD Screen itself remains functional underneath the cracked glass.
With the help of acoustic guitar high E string and heat gun, we were able to actually separate the glass from the LCD.

We had 2 screens; the first one was broken into many shard, wich ended up creating some white and black spots where the edges pressured while being removed. The second one just had a central broken line and was much easier to get done with this method.

First thing you have to do is create a way for the string between the glass and the screen on one of the edges, separating them with a knife. First, make sure to heat up the areas while working to melt the glue. Between glass and LCD there is a plastic-like layer wich i believe is also acting as a polarizing filter. In the first experiment we inserted the guitar string underneath this second layer, crating a totally white corner in the process You have to make sure you are taking out the actual glass only, using the knife blade on the LCD upside down putting pressure on the glass.
Then turn the screen on the front to look at the glue melting and and pull the string all the way, while someone heats up the area in advance. Wear some thick gloves!

The nicely-smelled glue dries up quickly, becoming much harder to clean up afterwards. We used plastic credit cards to remove most of the glue, and some solvent to take off the remains.
You might want to assemble the screen before cleaning up to make sure nothing broke, and to put some plastic zipties parts in the areas between the LCD and the plastic assembly that remains aroun the screen to prevent it from “floating” , as that could damage the data cables. You will understand what i mean when you do it 🙂

Notice the area on the right looks burnt out; it all went away after cleaning.

With the help of my dad’s skill, we were able to actually turn this into a rather unique design. We used foam and tape to keep the screen in place first, and then very strong double sided tape to put the frame on. The screen is now a bit brighter and actually looks crispier and easier to read, even though it seems to be more reflective. We still ended up with 2 small spots that are a bit dark, so we used the app Dark Boot to get the white apple on black background on startup, and a dark wallpaper. Please understand the main reason to do all this is to avoid wasting a new screen.

The late 2012 model is a quite nice performing machine with Thunderbolt port for external audio cards with DSP . The 2013 to 2015 models with Haswell and Broadwell cpus can even be undervolted for amazing efficiency and totally quite operation . Just make sure you install some DDR3L memory and a new SSD. Here is the r15 score for this machine.

The machine seems to run colder after this mod, and is definitely a lot lighter – even though the surface is now much more prone to scratches and permanent damage so i would not carry it around so much. Definitely give this a try if you want to save a lot of money and materials – and have a story to tell.