Film Maker/Network Engineer/hardware repair specialist
I find that the LCD is not as fragile as we all think. they are very much like any LCD on a tv or monitor. There is no extra glass on the front of a monitor. Not the 23 HP Pro Displays I have anyway. I know this because I punctured one moving my video wall. so I took it apart to know how its put together. I will say, there are several 'lens’ like sheets and a reflective (silver} sheets that are the same size as the panel. and a 1/8”piece of acrylic, all behind the LCD panel. Take care with them and clean as you would your monitor.
My suggestion is to stand the iMac up after the panel is secured back into the body of the iMac and clean while its vertical. took me 3 attempts before I realized that while laying flat the surface is large and collects dust with mind blowing speed.
good duct tape or gaffer tape wrapped around your hands makes an excellent glass removal 'tool'. Even clear packing tape works a charm.
Doing it today, let you know how it goes.
did you get yours done?