What a great idea! Thank you. I have a client of mine with slate tile that needs a refresh and this tip will really help.

Thanks for sharing. Now...if someone SITS on or places anything on the slate, is their COLOUR transfer?

Most likely...I have seen wood trying to pass as ebony darkened with shoe polish...and the color rubs off.
the same shine could be accomplished with a good paste wax.

You should really rub it in, and wipe excess off with a clean cloth. The same thing you would do if you used black shoe polish on your shoes or handbag. I think it is Kiwi black shoe polish I used, the flat can available at grocery stores. It did not produce a high shine on my slate, more like the original eggshell or satin finish. I had no problems with it rubbing off. In my opinion, it works perfectly.

My black slate is in a shower as the floor tiles. Bad building choice in my opinion, but looks good otherwise. It has copped someone cleaning it with harsh chemicals, so I wonder if this fix would work for me.

Sorry I'm a little confused over the statement.

Can you elaborate on 'copped'?

SJ Mc, do you have any advice or were you simply getting clarification?

Clarification. "Copped" isn't a word seen on the N. American continent. One of the few ways we see the word used is "to cop a feel". Which can't be readily translated in your usage.

A photo of what you are speaking of would certainly help. Slate can be damaged many ways. Without knowing what you are looking at, we are as much in the dark as you are.

I have an 8x8 area to cover. How to do avoid getting the polish on the grout lines?

Sre black slate is built up on the hearth on each side for sitting with pillows in back like bench seating. Do you still recommend shoe polish? It won't come off on clothing or to slippery