I pulled a couple of OEM fog lights from the PNP + the needed relays, switch, jumper, etc. to install in the sled. Both lenses were badly pitted. I wanted to polish them clear before using a protective film. Problem is the 'net is full of polycarb HDLT lens polishing, rather than GLASS polishing.
I found this helpful link of a BMW owner who wanted to restore his own.
As I owned a nice Bosch RO sander/polisher + a wide assortment of sanding disks I use for woodworking, I started with it. Very mediocre results. Why? The pad isn't driven; it just shakes around. If you press hard enough, the pad will stop.
I detailed the entire experience over on MVS [here], so I won't repeat all the mistakes.
I wound up using my dress press set to a spindle speed of 2650 RPM, a 3M medium H&L backing plate and the same 6" sanding pads mentioned above. As tempered glass is much harder than polycarbonate, you need more pressure & higher surface speed. You also need to sand dry.
The key ingredient to achieving water-clear glass is cerium oxide. I managed to obtain some from a local astronomy source and it just so happened to be the right grit for polishing rather than curve generating. Fortunately you can easily order red cerium oxide from the 'net. The product I used is about 13 microns, which is close to a FEPA P grit of 1500.
Here's the photos:
This is what both lenses looked like before. While the glass surface was clear, it was heavily pitted.
My previous best efforts resulted in this:
While much better, it's still not good enough. The light bulb reflection is smeared, the glass surface is now hazy and scratches remain.
My final efforts look like this:
The sky had clouded over by the time I finished, thus I had to use the shop light. It's difficult to take a photo of a polished, shiny surface however the lenses are now water-clear.
I'll cover this with a protective film, let it cure, then install them (finally).
I found this helpful link of a BMW owner who wanted to restore his own.
As I owned a nice Bosch RO sander/polisher + a wide assortment of sanding disks I use for woodworking, I started with it. Very mediocre results. Why? The pad isn't driven; it just shakes around. If you press hard enough, the pad will stop.
I detailed the entire experience over on MVS [here], so I won't repeat all the mistakes.
I wound up using my dress press set to a spindle speed of 2650 RPM, a 3M medium H&L backing plate and the same 6" sanding pads mentioned above. As tempered glass is much harder than polycarbonate, you need more pressure & higher surface speed. You also need to sand dry.
The key ingredient to achieving water-clear glass is cerium oxide. I managed to obtain some from a local astronomy source and it just so happened to be the right grit for polishing rather than curve generating. Fortunately you can easily order red cerium oxide from the 'net. The product I used is about 13 microns, which is close to a FEPA P grit of 1500.
Here's the photos:
This is what both lenses looked like before. While the glass surface was clear, it was heavily pitted.
My previous best efforts resulted in this:
While much better, it's still not good enough. The light bulb reflection is smeared, the glass surface is now hazy and scratches remain.
My final efforts look like this:
The sky had clouded over by the time I finished, thus I had to use the shop light. It's difficult to take a photo of a polished, shiny surface however the lenses are now water-clear.
I'll cover this with a protective film, let it cure, then install them (finally).