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How to Seal a Countertop Seam with Epoxy

Use this technique to create a tight, permanent, almost invisible seam in difficult-to-work-with countertop materials like natural slate and concrete.

More in Kitchen

  • Time

    2 hours

  • Price Range

    $1 - $50

  • Difficulty

    Easy

Highlights:

Step 1: Tape the Seam

Fit the countertop sections in position, with the seam tightly closed. Place a strip of blue painter’s tape directly over the seam.

Step 2: Mark and Score the Seam

With a pencil, make two to three reference marks on the tape perpendicular to (across) the seam. Use a carpenter’s square as a guide. Use a utility knife to score the tape on the seam.

score tape on seam with utility knife

Step 3: Epoxy the Countertop Edges

Pull the touching countertop sections about 3/4" apart. Each section will have half of the blue tape strip closely abutting the seam edge. Mix the epoxy and catalyst according to the manufacturer’s directions.

Use a disposable wood shim to butter the inside edges of both countertop sections with the epoxy.

Push the countertop sections back into place. Use your reference marks to line up the sections exactly as they were when you started.

remove doors of old cabinets

Step 4: Work the Epoxy into the Seam

Drag a flat, edged tool such as a utility knife blade over the tape to “squeegee” the epoxy into the seam. Repeat the process until you are sure there are no voids or air pockets. The epoxy should fill the entire seam level with the tape.

work epoxy into the seams with razor blade

Step 5: Finish the Joint

After the epoxy dries thoroughly, peel off the tape.

Finish the completed joint by carefully scraping and sanding away any tape residue and the excess epoxy.

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