Got new ceramic floor in the kitchen (wear rating 4), it is glazed.
However, the grouting used is very sandy, and porous. It comes off
easily where an excess of it was applied, for eg near the base trim.
I'm afraid if I mop too hard, it will come right off. Will a grout
sealer help make it solid? The contractor ran away w/o applying a grout
sealer, and told me that's extra, not in the estimate.

On another note, the floor is very cold (my house is on a slab). Would
porcelain have felt less cold, being that it is denser, and thus forms
a better barrier between the slab and tile surface? Had I known how
cold it is, I would have stuck to linoleum...

Thanks!
Vijay