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How to Make Concrete Countertops With Fiber Optics

By Kim Joyce
Fiber optics can create stunning lighting effects.
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Creating a custom light show inside concrete kitchen or bathroom counters is one reason to pour your own. The magic of embedded countertop lighting is the surprising effects you can achieve with illuminated fishing-line-thin acrylic fibers. There are never any bulbs to change -- light bounces back and forth along the fibers -- and, surprisingly, you also don’t need to wire counters for electricity.

Set up the sawhorses so your countertop mold is well supported in the middle as well as at both ends. Tape the stencil pattern to the bottom inside of the mold. Place the mold securely on top of the sawhorse supports. Drill a tiny hole for each acrylic fiber -- or a slightly larger hole for multiple fibers -- using the power drill. Remove the stencil once the pattern is complete.

Place the welded wire reinforcement or rebar inside the mold. Make sure it doesn’t interfere with the light pattern. Insert individual optical fibers through pattern holes so each one sticks out -- like bristles -- down through the bottom of the mold by at least 1/4 inch. Once all fibers are in place, tug each one to make sure they are snug.

Collect, bundle and label the long, free ends of the optical fibers -- the sections that will later attach to the illuminator -- according to the light pattern and color. Gather up and neatly tie these fiber lengths to reinforcement or rebar with plastic zip ties until all fibers come together at the exit point, wherever you have decided that will be. Tie them up and out of the way, attaching them to an outside support.

Mix the polymer-based concrete, following product instructions, if necessary; both dry and premixed versions are available. Make sure the concrete is fluid enough to flow to and around every fiber. Guide the concrete with your fingers as needed. Use the vibrator to settle and fully consolidate the concrete.

Let the concrete counter set for three days. Untie the fiber bundles and turn over the mold so the labeled fibers hang loose below it. Slip in shims all around the mold edges to loosen them and then lift the mold up and off. Cut off each optical fiber at the countertop surface with the razor-blade scraper.

Cure the concrete for four to 10 more days, depending on curing conditions. Use the wet-stone polisher to smooth the counter surface. Use coarse-textured finish pads and gradually work up to very fine ones as if sanding furniture. Wipe the polished surface with a damp rag. Apply the concrete sealer and allow it to dry.

Install the finished countertop, taking care not to damage the optical fiber bundles. Attach the fibers to the illuminator, pushing bundles through its metal plate. Cut the fiber ends with hot wire, which expands their size for better light transmission and also assures that they won’t pull out of the illuminator plate.


Things You Will Need

  • Counter mold (plastic, foam, laminated plywood)
  • Sawhorses
  • Light-pattern stencil
  • Masking tape
  • Power drill
  • Welded wire reinforcement or rebar
  • Thin fiber optic cables
  • Plastic zip ties
  • Illuminator
  • Fluid polymer-fortified concrete mix
  • Concrete vibrator
  • Cedar or other soft wood shims
  • Razor-blade scraper
  • Wet-stone polisher
  • Coarse to fine polishing pads
  • Concrete sealer
  • Hot wire cutter


  • When in doubt, start with fibers longer than you think you'll need. Fibers need to be long enough to follow the relevant "exit pathway" through the countertop to the exit point -- where all fibers come together -- and then on to the illuminator, which is usually set up beneath or otherwise near the countertop. The illuminator must be plugged in to a power source.


  • Be careful to avoid tangling or pulling loose tied lengths of optic fibers during concrete consolidation, or all your hard work may become a terrible mess.