How to clean silicon residue off glass?

[FishyIdea]

I'm replacing my cracked sump and cut my old glass baffles out of the old one. I'll scrape them down, of course, but how do I safely clean the oily residue offf the glass before installing them in the new sump?

 

[MarkO]

I'm replacing my cracked sump and cut my old glass baffles out of the old one. I'll scrape them down, of course, but how do I safely clean the oily residue offf the glass before installing them in the new sump?

diluted muriatic (hydrochloric) acid will take off any calcification. Alcohol will take off any oils.