My props have that hard calcium type of scale on them. What is the best way to clean them off? Is there a liquid/chemical solution that can be used as opposed to an abrasive approach such as scotchbrite?

Polishing compound on a buffing wheel.

Light mix of muriatic acid or wood chlorine. If it's mild. that stuff you use in toilet works a bit too.

Try lime away, works,or sulfuric acid. Be careful though stuff is tough but cleans stainless well

Stick them in a 5 gallon bucket with some vinegar and let them soak for a while.

Any cheap toilet bowl cleaner

3pointstar

On and Off bottom cleaner works like a charm.

A sponge soaked in CLR cleaner will melt that right off. Works great for getting baked-on scum off exhaust tips as well.

^^^^^ This,

Rinse props with Snobol, lime-away, or your pick of acid and then run through a full cycle (air dry not heat) in the dishwasher when the wife isn't home. Don't forget the jet dry and then polish.