Well, I did a trial with a few tiles and then covered them with polyurethane. The trial didn't necessarily go entirely to plan but I was able to establish that PU will be too soft. Epoxy is likely to yellow even indoors, so that leaves me with the following solution: 1. make the tiles thicker (not a big deal) use tile selection and a thicker tile bed to enable a relatively flat surface to be made 3. seal it with a thin polyurethane to protect from mess Thanks for the contributions.

Looking at the attached photo you can see compared to close to the wall the floor tiles are streaked with white stains. I have tried using vinegar and scrubbing brush and also other cleaning products....

Get a tile cleaning product from Bunnings. Will ensure that the integrity of the tile is not compromised. However, by the look of the stains it seems as though something has been used that was too abrasive, too acidic or that had bleach in it. I do not recommend to keep any product on for an extended period of time. 5 mins max application!

I’d go with timber or cork. Cork is great in a kitchen. Easy on your feet and joints and things are much less likely to break if you drop them. Especially as you age, tiles cause fatigue if you are standing in the kitchen for too long. Cork is now available in lots of different colours and styles including charcoals and greys that might compliment your slate. It’s not all 80s orange. Of course timber can look great too. Just make sure it’s ok for kitchen use.