Rakesh and I cleaned the ~ 30-50 contamination spots on XBM interior wall, a few feet away from cryo baffle, ranging in size from 1 mm diam. to 1" diam. We scraped the surface of these spots with small flat head screw drivers and a tool with a pointed edge, and collected the brown/black flakes, to be analyzed via FTIR. We wiped with IPA wipes and also tried acetone and methanol (wiped away same as IPA). The spots leave a stain on the SS wall. We are not able to remove 100% of this material with our cleaning technique. The beam tube wall is rough, so wiping is limited without creating other issues with wipe shedding. The location of these spots is two tube welds in from cryo baffle.
JPL results here: https://dcc.ligo.org/E1700405