  We report on the mechanical loss in fused silica samples with various surface
treatments and compare them with samples having an optical coating. Mild
surface treatments such as washing in detergent or acetone were not found to
affect the mechanical loss of flame-drawn fused silica fibers stored in air.
However, mechanical contact (with steel calipers) significantly increased the
loss. The application of a high-reflective optical coating of the type used for
the LIGO test masses was found to greatly increase the mechanical loss of
commercially polished fused silica microscope slides. We discuss the
implications for the noise budget of interferometers.
