Routing a Countertop for an Inset Tile
How to set a repair flush with a damaged surface
Last year, in our kitchen a tea towel caught fire from a lighted candle and partially melted an 8-inch-square area of plastic laminate countertop. I'm hiding the damage with a ceramic tile, but was wondering if I could inset the tile into the countertop for a more finished look.
— Pegeen, Minneapolis, MN
Tom Silva replies: Not a problem. You just need a plunge router and a ½-inch hinge-mortising bit with top-mount bearing. With this bit, you can cut a shallow, flat-bottomed trough (called a mortise) about 1/16 inch wider than the tile on every side. You can fill that small gap with adhesive caulk, which will seal out moisture and hold the tile in place. The only limitation to using a router is the size of its base; you can't get any closer to the backsplash than half the base's diameter.
To get a nice, crisp mortise that will match your tile, make a jig out of a piece of ¾-inch plywood. Just lay the tile on the face of the plywood and mark around its perimeter. Cut along that line with a jigsaw, remove the tile-shaped scrap piece, and you'll have the edge you need to guide the router.
Secure the jig to the counter with hot-melt glue and set the router bit to cut at a depth at least 1/8 inch less than the thickness of the tile; you want the surface of the tile to be higher than the surrounding countertop so you can park a hot pot or pan there without scorching the laminate. (Be careful with really thick tiles; you don't want to cut more than halfway through the underlayment.)
Cut the mortise by first running the router in a clockwise direction around the inside edges of the jig — that gives you the cleanest cut. Then pry the jig off, reset the bit depth, and hog out the rest of the mortise with methodical back-and-forth swipes. If you like the look of the tile once it's glued in place, use the same template to inset matching tiles in other places around the countertop.