Agreed on the acid. Well diluted, well ventilated, well protected and neutralize after use with baking soda.

I spend a lot of time cleaning glass shields for lights at work that get get deposits on them (lab monkey in a solar research lab). I've found that muriatic acid (hydrochloride acid) and nitric acid work the best; in fact, mixing the two together works great. As Tim said, 4 parts water to 1 acid. I just leave them to soak for a while, rinse well, then give them a quick once over with windex to get rig of finger prints and streaks.

I had an Italian chemistry prof who used to tell us : "Do as you oughta, add acid to watta". (gotta say it with a super think Italian-American accent). A decade later and I can still hear him in my head every time I touch the acids cabinet.

I'm gonna have to keep this in mind

I had a prof with the same expression, more of an English accent to it :) Every time I touch a bottle of acid, I hear it -lol
I also never forget the SG of mercury is 13 point freakin' 6!!!! (well, rounded up)