Grouting slate tiles

[Andrew Bodenham]

We have laid some nice green slate tiles for a new hearth in our kitchen.
Purists will be pleased to hear that they are bedded on lime mortar.
Now they need grouting - suggestions please!
I think that the grout colour should be a mid grey, and I'm tempted to try straight lime putty with a dash of cement dye, but wonder if this will stain the slate during application, and be durable enough when set.

And what about "sealing" the slate surface? The suppliers were trying to sell us a tin of petrochemical glop, but we declined. Maybe the tiles don't need any surface treatment at all, or is there some "natural" product which will bring up the colour and help to srug off spills etc.?

Ideas / experience please.

 

[Mark]

depending on the slate you may find that without some sort of coating it rubs and marks things. I used slate for kitchen window cills years ago. I thought they looked quite good in the situation, but without sealing them the textured surface got noticeably dirty quickly and also made things placed on it a bit messy.

That was before enlightenment re breathability/natural stuff so I used the chemical that Fired Earth gave me. Now I would try wiping with oil on a test piece to see how that did.