How to clean a slate/marble clock case

[Weight Driven]

I know this question has been brought up before but I can get nowhere with this new search in past posts. I have a Seth Thomas and Sons slate mantel clock that apparantly has moisture damage as it has white spots over the entire case. My question is how would I remove the white spots. It is a two tone case but mostly black in color. Thanks for any help with this.

 

[eskmill]

I believe the white spots are actually the natural color of the slate or stone. Those expert in the care of black stone clock cases generally agree that the finish is artificially applied; dyed black or colored with a black wax. I suspect that the natural color of the slate varies depending on the location where the slate was mined. 'Most I've seen is kind of gray.

A member, Jim Glidewell, who specializes in restoring black mantel clocks advocates the use of progressively finer abrasive papers to prepare the slate for re-finishing but first he repairs any chipped areas with a metal filled epoxy resin. His choice is silicon-carbide (automotive) finishing abrasive paper wet rubbed beginning with 200 or 320 grit and finially using 1000 fine paper and lots of water.

The prepared case is an unsightly gray color but extremely smooth. His choice is a black wax sold in hobby stores named "Rub 'N Buff." It's semi-fluid and not very pretty until buffed mechanically. He uses a stiff rotary brish in a Dremel tool at high speed. The "Rub 'N Buff" black wax color requires surface heat generated by the friction of the rotating brush on the waxed surface. It produces a dense black glossy mirror like finish to the slate. It takes time to do a right job.

Others have suggested black shoe polish to restore the color of the slate and I suppose that there are proprietary shoe polishes that may work as well as "Rub 'N Buff" but don't respond to the burnishing effect of the fast rotating brush.

 

[High_Time]

Hi WD,

The best product I have tried is called 'Back to Black', and is available from Timesavers.

 

[Weight Driven]

thanks to both for the replies, some great and useful information here, just what I was looking for. Much appreciated.

 

[BIG D]

If you are looking for an easier way to make it look better.........
Rub it down with automotive engine oil. I have an Ansonia slate case that I did this to about 3 yrs ago and it still looks nice. It does not produce the high luster you may want, but does black it back up nicely.

Good Luck!