I created a grid of reinforcing rods across the top and wired it to the bent perimeter rods.
To prevent the forms and screeds from spreading while I compacted the mortar bed, I also used tie wire to draw the opposing sides together, running it beneath the reinforcing rods.
I used a trowel and damp sponge to spread a 1/8-inch-thick layer of latex thinset mortar over the concrete base to ensure that the mortar bed would stay bonded to the base.
Spreading the mortar with a sponge
While the surface of the thinset was still moist and tacky, I spread and compacted latex deck mud over the top, then used a straightedge and trowel to remove the excess.
After screeding the mortar bed flat, I used the steel trowel to add mortar as needed to maintain the slope.
I followed with a brisk "sanding" with the wood float, leaving a coarse surface to ensure a good bond between the tile and the setting bed.
Once the thinset had hardened, I cut and dry-fit the 12-inch tiles, recut those affected by the porcelain inlay tiles, then installed the tiles with the perimeter tiles hanging over the edge.
To strengthen the perimeter of the top, simplify maintenance, and give the countertop a more pleasing appearance, I gave the underside of the edge a 3/32-inch bond coat of latex thinset mortar followed by an application of densely packed mortar, which I let set up before screeding with a margin trowel.
After six years of regular use the slate countertop with the curly edge is still working great.
The completed tile job
