Looking good Fred
After removing the black
paint that covered our frames (icky job), we did ours by hand, rotating between a very fine grit sandpaper and the "green sponge," they have a nice brushed finish look to them. I imagine it depends how "finished" the look you're going for is. When we reinstalled the
windows, the butyl tape squished out and got all over the frames, had to give a few more
light cleanings anyway once installed.
We were surprised to find that the aluminum window frames were nice quality, not just a "punched out" thin aluminum frame. As you can see in the picture, the frames look good with the belly band.
Are you changing out the rubber moldings, tracks etc... on all the
windows?