What's the best way of creating a good long lasting shine on slat floors? I have a slate floor which goes from my kitchen through the utility room and into the hallway. Originally I used a purpose built slate floor sealant and applied multiple coats. It never went glossy and the soft sheen it had immediately after application has disappeared even in areas which get no traffic. I was thinking about varnishing it with pollyutherene varnish (you know, the good stuff) but I've seen a lot of recommendations against doing this. So what is the correct way to get a shine like in the example photo?