Trying to make a shield for 9004. Used 9004 HID bulb to measure.

While trying to put the shield on today, I noticed a 1/8-inch long mark, maybe a scratch, or even I touched it by accident.

How to clean that off? I saw a thread about this somewhere before, but could not find it again. Any suggestions welcome.....

The tools I have in hand: methanol, ethanol, dust-free wipe, nitrogen blow gun, cotton swab, DI water,............

Thanks~

P.S. I tried to take a picture of it, but could not see that well in the picture. Let's assume it's just something on the surface.

 

Googled it......

Rubbing alcohol: http://www1.diynet.com/diy/ab_parts_...270898,00.html