I don't think all slate takes sealer. Read somewhere that it's not porus enough. Best ask the supplier what they reccomend for that particular stone/source.

I suspect it may help other people to know which room you are going to install the stone in

Nothing wrong with riven slate in a kitchen or any other floor for that matter if its laid well like this

I assume you are using the two surfaces on the same floor?

Sealing will depend on the look you want. If you want to keep the slate looking like it is out of the box/crate then something like Lithofin MN Stainstop will do the job. If you want it to have more of a sheen and enhance the colour (wet the slate with water to get an idea of the look) then something like Lithofin MN Slateseal will work well. Don't be tempted to buy cheap sealers like plasplug or even Lidls

http://www.extensive.co.uk/section.php?xSec=18

Apply sealer after laying then again after grouting.

Also remove any loose layers from the slate before laying and grade them for thickness if possible, a wide joint helps prevent oneven edges.

Jason

virtually every tile shed warned me about slate on a kitchen floor,difficult to clean,tricky to lay unless its graded for thickness and some slate will laminate if its in a high use situation. i laid 22 metres of 450 sq satin porcelain on my kitchen floor which provides a good flat background for the cabinets and worktops.it cleans easily with floor cleaner and the satin finish is much less slippy than gloss.but it still looks nowhere near as good as the honed slate

best regards

wretch