This is an excellent topic and I really hope this one takes off so others can share their tips and tricks for preserving these beautiful machines.
Here's my process and how I restore the machines that I add to my collection. I should note that with a few exceptions most all of my machines that I've collected at this point have arrived in various stages of neglect. Specifically the usual amount of having been tossed around with no care about scratches or dirt or even paint transfer from scraping walls. With that in mind I've taken tips and techniques from others to come up with my process for restoring plastics.
For this example I'm going to use the Onyx2 that I rescued from an e-waste recycle center a few years back. It was in really rough shape and needed a lot of work but it now sits looking factory fresh.
** Disclaimer ** No matter what, there is no perfect solution to removing scratches. Once they're there, the only way to truly remove them is by removing layers of the plastic around it in order to bring everything down to the level of the scratch. As we all know, SGI's have textured plastic and this is not a viable method of dealing with them. The process I will outline below makes use of multiple products and techniques to help minimize the appearance of scratches so that you would have to be looking in exactly the right angle or, even better, very very closely to see any marks. This is something I am quite pleased with and hopefully others will find it useful as well.
Step 1
Every machine that I pickup goes through a thorough cleaning. This is accomplished by complete removal of all plastic skins. If it's a machine I haven't had in my collection before I make sure to reference anything and everything (web, manuals, etc.) to make sure I don't break the skins taking them off.
Once removed and depending on the size of the skins I will take them either to a utility sink or a tub and give them a cursory rinse with plain water. I don't do much more than get things wet.
Next, I liberally apply Simple Green all over the skin(s) and allow it so soak into all cracks and crevices for at least 10 minutes. For skins that are exceptionally dirty, this process will be repeated.
After leaving them to sit, they get a scrub with a nylon cleaning brush. I have not found this to cause any damage or scratching of opaque plastics. In the case of the Onyx2's translucent front panel I made sure to use a different process, avoiding the scrub brush.
Once scrubbed, a thorough rinsing is accomplished and the parts are removed to be dried and then left to sit.
Step 2
Depending on what is left on the skins I use three different products to help with getting things back in order. For anything sticky (inventory tags, sale tags, etc) that have left residue, I will use Goo-Gone citrus-based cleaner to gently remove any stuck adhesive. For any paint marks or stuck dirt I will turn to a magic eraser. The catch here is that you have to go slowly, use even pressure, and know when to call it good. Since magic erasers have a slight abrasive quality to them, overuse can result in flattening down the texture of the plastic and leaving a shiny spot that's not going to come out. Make sure to stop often and ensure that you're not starting to get the plastic color on your eraser. If you are, then it's time to call that spot good, even if it's not 100% perfect. Lastly, for scratches, I use Meguiar's Ultimate Compound. This is an automotive product designed for polishing scratches out of paint. It is EXCELLENT at helping to remove light scratches and does an extremely good job at minimizing deeper ones on plastic.
When using Ultimate Compound, I apply a quarter size drop to the spot (or more if it's a long scratch) and use a microfiber cloth to slowly polish the scratch using circular motions. As with the magic eraser, stop often and check your cloth to see if any plastic color is being transferred. If done slowly with even pressure, this process will really do wonders to make scratches either disappear or look much less noticeable.
Step 3
If I've done any part of Step 2, it's time for a quick Simple Green bath. This one is quick--no need to let things soak. I just want to get any residue from the cleaning process off.
Step 4
By now the plastics are completely clean and I've removed any paint marks and minimized any scratches to the max extent I possibly can. At this point the plastics likely look a bit dull and some of the scratches are still visible (this step will help them disappear even more). It's time for Aerospace 303.
Depending on how scratched the plastics look and how chalky they appear, I will use one of two techniques. The first is to spray 303 on a microfiber cloth and start to wipe down the skins. I'll do this a few times, making sure to leave as even of a finish as possible. The second technique involves soaking the plastics in 303 and leaving them to sit. This gives the product time to sink into the top layer of the plastic and really brings the luster back to it. It has the added benefit of helping to change the reflectivity of the plastic and masks any of the scratches that couldn't be completely removed earlier. I'll make sure to wipe the skins down with a dry microfiber cloth after letting them soak to make sure I wipe off anything that hasn't soaked in.
I will typically reapply 303 every few months to my different machines. It keeps them looking new and has the added benefit of blocking UV.
Step 5 (as needed)
If you have any translucent plastics, I recommend using a plastic polishing compound and microfiber cloth. I personally use a three-step system from Novus and find it to be very good.
Example Photos
![[Image: 37573081-b757-4fa0-8dd2-a5d5998f262c-ori...fit=bounds]](https://hosting.photobucket.com/images/s152/SomeCorellianGuy/0/37573081-b757-4fa0-8dd2-a5d5998f262c-original.jpg?width=1920&height=1080&fit=bounds)
Note: If you happen to have a deskside that squeaks a lot when you try to roll it around, Blaster Dry Lube works really well to get rid of that noise!