How to Finish Edge of Mosaic Tile Backsplash

Installing a mosaic tile backsplash can add visual interest and color to your kitchen or bathroom. However, finishing the edges of the mosaic tiles properly is an important final step. Here is a detailed guide on how to finish the edge of a mosaic tile backsplash.

Select an Edge Piece Material

Choosing the right material to finish the edges of your mosaic tile backsplash is important both for aesthetics and functionality. Consider the following popular options:

Bullnose Tile

Bullnose tiles have a rounded finished edge that creates a smooth transition from the wall to the outer edge. Bullnose tiles come in many sizes, colors, and materials to match or complement your mosaic tile.

Pencil Liner Tile

Pencil liner tiles have a narrow rectangular shape designed to tightly fit between the edge of the mosaic tile and the wall corner. Pencil liners create a clean finished look.

Metal Trim

Metal trim like brass, copper, or stainless steel can create a stylish accent border. Make sure to select metal trim that is compatible with the mosaic tile material.


Wood or plastic molding can provide a budget-friendly way to finish mosaic tile edges. For moisture-prone areas, use molding made of plastic, resin, or PVC.

Prepare the Surface

Before installing the edge piece, ensure the edges of the mosaic tiles are straight, clean, and even. Use a utility knife to trim any uneven edges. Vacuum away any debris or grout residue along the edges.

Apply caulk or thinset mortar along the side walls and mosaic tile edges. This helps adhere the edge pieces. If using metal trim, apply 100% silicone caulk to prevent rusting.

Cut the Edge Pieces

Measure the length of each edge and mark cuts on your edge pieces with a pencil. Use a wet saw fitted with a tile blade to carefully cut the edge pieces to size. Bullnose tiles and pencil liners should have a factory finished edge on one long side.

Cut molding and metal trim to fit using a hacksaw or tin snips. File, sand, or grind any rough edges smooth.

Set the Trim Pieces

Run a bead of tile adhesive or thinset mortar along the side wall where the edge pieces will sit. Press each edge piece firmly into place, lined up flush with the outer mosaic edge.

Use painter’s tape to hold pieces in place until the adhesive sets. Remove any excess adhesive squeezed out along the edges.

Allow 24 hours for the adhesive to fully cure before grouting.

Grout the Seams

Mix non-sanded grout according to package directions. Apply grout using a rubber grout float, forcing it into the seams between the mosaic tiles and edge pieces.

Wipe away excess grout with a damp sponge. Clean any haze or film off the tile surfaces with a soft cloth.

Allow the grout to fully cure for 48-72 hours. Apply caulk between the bottom edge piece and the countertop.

Seal and Polish

Once grouted and cleaned, apply a penetrating sealant to the finished edges according to the product instructions. This prevents moisture damage and staining.

For metal trim, use a polishing cloth to buff the trim edges to a brightness sheen. Apply car wax periodically to maintain the polished look.

With the proper edge pieces cut, secured, grouted, and sealed, your mosaic tile backsplash edges should have a fully finished integrated look. Take time to properly complete this detail work for a professional-looking backsplash project.

Frequently Asked Questions About Finishing Mosaic Tile Backsplash Edges

Here are some common questions about properly finishing the edges of mosaic tile backsplashes:

How do I measure for edge pieces?

Carefully measure each edge length needing trim. For inside corners, measure each wall section separately. Add 1-2 inches to allow for extra fitting adjustments.

Should I use bullnose or pencil tile on the edges?

Bullnose has a smoother finish, while pencil liner fits tighter to the corner. Choose based on the look you want and availability of matching trim.

What adhesive is best for the edge pieces?

Thinset mortar designed for tile provides the strongest bond. Check that the adhesive is compatible with the mosaic tile and edge piece materials.

Should I use sanded or unsanded grout on mosaic tile?

Use unsanded grout for mosaic tiles with grout joints 1/8 inch or smaller. Sanded grout is best for wider grout lines.

How long should I wait to grout the edges?

Allow 24-48 hours for the tile adhesive to fully set and bond before applying grout between the mosaic tiles and edge pieces.

Can I use metal trim on floors or wet areas?

Metal trim can rust over time from moisture exposure. Use caution and apply sealant if using metal edges near water.

What’s the best way to cut bullnose and liner tiles?

Use a wet saw fitted with a diamond tile blade. Cut slowly to avoid chipping the bullnose or pencil liner edges.

How do I finish the bottom edge of the backsplash?

The bottom edge can be finished with a bullnose tile or by applying caulk between the mosaic tile and countertop.

How often should I re-seal the edges?

Reapply sealant every 1-2 years depending on use and exposure to moisture. This prevents cracks, stains, and damage.


Installing trim or edge pieces is an essential finishing step with mosaic tile backsplashes. Following a careful process of selecting quality edge materials, precisely cutting and fitting the pieces, proper use of adhesives and grout, and sealing and polishing will result in a clean finished edge that beautifully frames your mosaic design. Paying attention to detail on the edges can elevate your whole backsplash and give it a professionally installed look.