Exploration into the Retr0bright world...

Hello everyone! I would like to share my experience restoring old computers to its original (or close to) beige/grey colour. 

If you are reading this post, chances are that you know what retrobright (or retr0bright) is. In any case, here is a short explanation: ABS plastics were largely  used in computers and game consoles in the 80s, 90s and early 2000s. Plastic manufacturers mixed bromine within the ABS formula to give these plastics fire retardant properties. With time, these ABS plastics turn yellow due to a chemical reaction between the bromine and UV light (radiated plenty by the Sun and also fluorescent lights among other sources).

The state of my vintage Apple keyboard prior to the process

Rescuing a Macintosh SE

I got this Macintosh SE SuperDrive (or FDHD) as part of a complete package, with keyboard, mouse, the original Apple manuals (including the stickers), an Apple StyleWritter II printer, a 1200 bps modem and even some early 90s software. 

The seller tried to power it on and sent me this photo of what he got on the screen: 

Strange wavy pattern with a faint checkered board in the back

I researched for such pattern to get hints on what could be going on and heard it could be: