ATM Silicon on mirror face

[RICHARDBAL@aol.com]

On behalf of a friend who is trying to resurrect a 4" Newtonian he purchased
25 years ago when he was a teenager:  He recently had the mirror re-silvered.
While mounting it on the cell he managed to get a smear of silicon on the
mirror face.  He has been reluctant to attempt cleaning the mirror for obvious
reasons. 
 
Does anyone know how to get silicon off a mirror face?  Can it be done and if
not what next?

Thank you,
Richard Ball, Oak Park, IL
for Larry Ritsert  (LRitsert@aol.com)