Concrete Countertop With Integrated Sink and Fiber Optics

We were remodeling our bathroom and I wanted a unique option for the countertop and sink. I finally decided to make a concrete countertop after seeing other instructables on the subject. I had to make it my own with the sink and adding lights. I found some different ideas for how to do the fiber optics, normally sticking straight through the surface to show a bright dot. I wanted to diffuse the lights through the colored glass. I found it very difficult to find any step by steps for how to do an integral sink so I decided to tackle it and provide a resource for others. Hopefully this helps. Let me know if anyone has any questions!

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Step 1: Materials

Before you do any work you need to collect the materials. Here is a list of the materials I used:

  • 3/4" melamine sheet - 4 'x 8'
  • (2) 80 lb. bags of Quikrete 5000 (can use equivalent)
  • 100% silicone caulking (I used black)
  • Spray adhesive
  • Glass
  • Door laminate or cardboard strips
  • Hot glue
  • Bondo
  • Spray lacquer
  • Various screws
  • Microfiber cloth
  • Remesh
  • Wire

For the lights I used a 75 strand .75 fiber optic lighting cable lit by a 6W RGB LED illuminator with RF remote. I purchased both items from eBay. These happen to be the ones that I purchased and they worked well for me. I have no affiliation with either seller.

Fiber Optic Lighting Cable

LED Illuminator

Here are the tools that are needed:

  • Hot glue gun
  • Wet polisher w/ diamond pads
  • Diamond turbo cup for grinder or polisher
  • Various trowels
  • Concrete mixer or mixing tub and shovel

I bought some green decorative glass from the dollar store. Since they were in pebbles and I didn't want the round shape so I decided break them. In order to do so I placed them on a concrete block and covered them with canvas before breaking them with a hammer. This prevented the shards from flying all over. Regardless of the canvas, make sure to wear safety glasses!

Step 2: Template

After you've gathered all of the materials and tools the first step is to make a template. I first took the cardboard and cut it into strips. This is often done with the door laminate but I had cardboard on hand from the new vanity. To make the template you place the strips along the wall and measure the proper overhang off the vanity. Use the hot glue gun to connect the pieces together. If the wall is really crooked you will have to glue small pieces along a larger straight piece to accommodate the curve. Make sure all of your cardboard or veneer is flush in the corners to give you a good corner.

I made two separate sink shapes out of cardboard to determine what looked best in the new vanity. I ultimately chose the smaller sink.

Step 3: Build Form

Once the template has been made and the sink size and shape has been decided it is time to make the form. Place the template on the piece of melamine that you will be using as a base. This will end up being the top of the countertop since it will be formed upside down. Trace the template onto the melamine. Rip some strips of melamine to be the sides of the countertop. I decided to make the front and exposed side to over hang a little bit. Because of this choice, I ripped the strips for the front and right side 3/4" taller. I place those strips along the lines that I had traced out and pre-drilled and screwed up through the bottom. I then used the black silicone to seal the inside edges and give the top a small radius.

It was then time to make the form for the sink. I chose to go with the ramp sink style sink I wanted to build it all out of melamine. This shape eliminated the need for me to fabric form or make a fiberglass mold. I built a trapezoid box the size of my cardboard template. I cut the piece that would become the bottom of the sink into three pieces so that I could slope the bottom toward the drain. I put a small shim between the back wall and the bottom of the mold to help with that slope. I ended up going with a 1/4" per foot slope in the sink. Fill in the voids created from the screws and from sloping the sink by using Bondo. Once the Bondo is sanded cover it with a coat of sealer. I used a spray lacquer that I had on hand. Silicone that inner form to the base sheet of melamine to seal it in place like you did with the previous interior corners.

Lay out the holes needed for the faucet and glue in a plastic pipe for knockouts. For the drain, create a foam cut out the diameter that you need for the drain hole. Place a washer that is the diameter and thickness of the drain trim on the portion of the mold that will become the bottom of the sink. This allows the trim the be countersunk in the water to drain freely. Glue and silicone the washer down then glue the foam on top.

Next, build the portion of the mold that will from the outside of the sink. Measure to give an 1-1/2" offset from the inside form that you already built. You want to make sure that it is offset from the hypotenuse, back wall, sides, and portion that will be the bottom of the sink. You only need to build the hypotenuse, sides and back for this part of the form. I also built wings off of the sides so I could screw it down to maintain proper thickness of the sink and countertop.

The last portion of the form was to cut 3/4" strips with blocks to screw to the form and create the offset lip. The majority of the countertop that I made was 1-1/2" and the edges that you see were 2-1/4".

Step 4: Add Reinforcement, Glass and Run Fibers

Cut the remesh to fit in the form. Bend the mesh up around the sink to provide reinforcement there as well. Place screws around the outside of the form and attach wires to the remesh to hold it at least 3/4" off the surface that will be the top of the counter.

After the reinforcement has been placed it is time to place the decorative glass. Apply the spray adhesive to all inside surfaces of the form. Lay out the glass of both colors in a pattern and placement that you prefer. Use the hot glue to attach the end of fibers to pieces of glass. I chose to attach the fibers to the glass to help diffuse the light rather than have the fibers exposed on the surface. Run all of the fibers to one spot so you can put them all in one illuminator. Glue the fibers along the remesh to help ensure that the fibers do not move when the concrete is being poured.

Step 5: Mix and Pour Concrete

Mix the concrete according to the directions. I used the liquid color to achieve the tone that I wanted. I made sure to make plenty of tests to find the right ratio of water, color, and concrete. Write this information down so that you can duplicate that in all batches and later for the slurry. For larger batches you will need to mix using a concrete mixer. Since I only needed two bags I mixed the concrete in a mixing tub with a shovel.

Carefully place the concrete around all of the fibers that you glued to the glass pieces. I placed the concrete with a small trowel. I enlisted the help of some friends to make sure I could to get the concrete packed down around the glass and fibers while being careful to not pull them loose.

Vibrate the concrete periodically with an orbital sander without any paper on to reduce air bubbles and increase fluidity. Once you pack enough concrete on top on the inner portion of the sink you can attach the outer sink form. Pack that full of concrete and vibrate all sides of it. Screed all excess concrete from the flat and sink portions of the form using a board.

Once everything is cleaned off make sure to cover the poured concrete with plastic to retain the moisture for curing.

Step 6: Remove Form and Hone/Polish

Since the countertop is thin we want to wait so that they are more fully cured before removing the form. Based on the manufactures instructions you should wait about 7 days for the concrete to reach the advertised 5000 psi strength. I did not put any mold release on the inner sink form. Because of that I had to chisel the inner form apart to be able to remove it.

I used the diamond turbo cup the expose more of the glass that I placed. I also like the look of more aggregate for the bathroom we were placing it in. This will also expose more pinholes and airholes in the surface. Since I do not have a polisher with a water feed I had a friend misting the surface with the hose as I went. The polisher I used was borrowed and I would love to win the concrete and casting contest to do more countertops throughout the house in the future.

I rounded over the lip from the top down into the sink with the turbo cup to give a nice smooth transition.

Step 7: Slurry the Pinholes and Polish

Using the color ratio that you wrote down earlier you can mix up a slurry using concrete without the aggregate or just cement with acrylic. Rub this over the surface and make sure you're wearing gloves. Once that dries in about an house you can begin to polish the surface. I started with 50 grit and worked up to 400 grit. Most sealers tell you to stop at 200 grit but the one I was using recommended between 400 and 800. Make sure to consult the sealer you are using before you polish all of the tooth away from the surface for the sealer to attach to! Make sure to wear all of your safety equipment like earplugs, glasses, and gloves while polishing like I so poorly wasn't in these pictures. I assure you I started right after they were taken!

Step 8: Apply Sealer and Install

I used the TK6 Nanocoat sealer for my project. You can apply this sealer with a cloth, roller, or by spraying. I chose to wipe on the sealer with a microfiber cloth. For the first two coats make sure to dilute the sealer by 10-30% with water. Then apply at least a few coats undiluted. Make sure to wipe it on quickly and circulate air with a fan right after application. With a wipe on coat you only need to wait about half an hour between coats. I ended doing about 5 undiluted coats.

I again recruited my friend to help my carry the countertop in place. Set it on the vanity and place dabs of silicone to adhere the top in place. The weight most keeps it in place but the silicone helps ensure its placement. Also caulk to the walls with clear silicone to seal the top from water dripping down the walls.

Attach the illuminator to the back wall of the vanity and plug in the cord to an outlet. I added an outlet inside the vanity before installing knowing that I would be plugging in the lights. Feed all of the fibers into the illuminator and you're good to go with your lights!

Step 9: Enjoy! and Future Improvements

Enjoy your new countertop with integrated sink and fiber optic lights! Since the remote is RF it works even outside the room and can put the lights on different modes from flashing to single colors to fading between colors. Because of the glass the lights are not super bright during the day but they make for a pretty radical night light.

Slightly shaky video of light test in the dark

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    15 Discussions


    1 year ago

    State of the art right there! Gorgeous!


    3 years ago

    this is fantastic


    3 years ago

    Nice work, and a lot of geometry. I'm doing my first lit concrete top for a buddy. Is there anything you would do different? This looks like it worked pretty well.

    2 replies

    Reply 3 years ago

    Thank you! One issue that I did have was tight bends with the fibers made the glass want to lift. This caused me to lose some lights on one side after pouring. Make sure you keep your fibers organized as you run them. Drilling holes to put the lights through and putting silicone on the bottom side works well too. You get a brighter, more concentrated light this way. Good luck! Post pictures!


    Reply 3 years ago

    Will do !! Thanks for the tip!


    4 years ago on Introduction

    Interesting design! Why didn't you include a sink overflow? Have you found that the sink drains slowly because of that?


    5 years ago on Introduction

    Congratulations on being a finalist in the Concrete and
    casting contest! Best of luck to you!


    5 years ago

    Looks great. But, as a professional electrician I recommend you replace the outlet with a ground fault interrupt (GFI) outlet. It's code requirement in most places. And could save your life.

    3 replies

    Reply 5 years ago on Introduction

    Thank you! The outlet under the sink is run off the GFI above the countertop next to the light switch. I was always under the impression that more than one GFI was not needed in a circuit. Otherwise, I will gladly change it!


    Reply 5 years ago on Introduction

    You are correct. I didn't know it was already in a gfi circuit. Some places require that the outlet must be marked as "GFI Protected". It's just my personal habit to mark them as such, just to cover myself.


    Reply 5 years ago on Introduction

    I haven't seen that by me but that's a pretty good idea. Thanks for looking out!


    5 years ago

    wow thats great. gave me a few good ideas and i would love to build something like it. maybe with all white lights so it looks like stars?

    how is it holding up so far?

    1 reply

    Reply 5 years ago on Introduction

    Thanks! You should give it a try! The illuminator that I bought is cable of doing a single solid color, like white, as well. But you could probably make something that would work for cheaper with some white LED's. Or some illuminators have a "twinkle wheel" which would be really cool. You could also dye the top black complete a star theme!

    It hasn't seen much use, yet. I just got it in place in time for a last-minute entry to the concrete contest. I can update you later.