Fiber-Optic Accented Outdoor Concrete Bartop/Table




Introduction: Fiber-Optic Accented Outdoor Concrete Bartop/Table

So I had been asked about making concrete countertops and we decided to try a simple, outdoor table to go next to the grill as a practice run, since we had never made anything out of concrete other than setting fence posts and a shed floor. We also had a small undermount bar sink found at Habitat for $10 so we wanted to incorporate that into this table.

Step 1: Building the Form

First, we made a form out of a 4X8 sheet of 3/4" thick melamine. I angled the front corners because this would end up being head height for a child and, being concrete it is going to win a head-butting contest. My form was about 6' long X 24" deep by 2" thick

We also made a well through the form to hang a sink beneath. For that we used vinyl landscape edging (also a Habitat find). we cut the shape (a rectangle with rounded corners) for the sink well out of the melamine, and cut the landscape edging longwise so it would be the same height as the sidewalls of the form when done. This was to allow us to screed the concrete across the whole top of the form after pouring the concrete in. Hot glue was used to secure the the vinyl to the form with some scraps cut and placed inside to brace it on the ends and sides. Ultimately the edges were caulked with a thin bead of silicone and the well was filled with sand so it wouldn't compress when the concrete was added.

Step 2: Adding Lights

We found these Fiber-Optic lights on Amazon for $50. They have 150 Filaments.

Some wire concrete reinforcement was cut to fit within the mold, and we used a couple boards across the top of the form to suspend it so when concrete was added it wouldn't get pushed down against the bottom of the form, which will ultimately be the top surface of the table.

Then we arranged the light fibers into about 6 groups across the length of the table, with the trunk of all the fibers coming out near (too near in hindsight) the sink well. Next time the fiber trunk will come out near the middle, away from everything else including the future wooden legs which hold the table up. We used zip ties to secure the 6 bundles of fibers to the reinforcement wire so when the concrete was added there would be less stress on them. The fibers are pretty flexible, but if you bend them so much that they crimp over, most of the light will not get through that crimped area. In the end I also had 10-12 fibers coming out the bottom of the table with the rest of the trunk that got cut somehow. I'm not sure how they got cut, but I made the table thicker than I would if I did it again (see the section: Wish I didn't know now what I didn't know then) so there are 4 80# bags of concrete in my table plus the water (not sure if that adds to the final weight or not) so 320# at least in the top alone. I suspect they got crimped hard enough to break them in two while we were flipping the table or pouring the concrete.

Once the fibers were pretty evenly distributed across the length of the table, we drilled small holes in sort of a random 'starry sky' pattern in the bottom of the form, cut the fibers to length, dipped the ends in hot glue and glued them into the holes hoping when we added the concrete they would stay put. I think they all did or at least the vast majority did. The smaller fiber bundles and sometimes individual fibers were also zip tied to the reinforcement wire if it looked like it would help them stay put. We also put a few fibers the same way into the side of the form that would be the front of the table in the end, and through the vinyl wall of the sink well. Once all that was set, we were ready for the concrete.

Step 3: Adding the Concrete

So for this step, we were super-lucky to have a friend with a concrete mixer which he graciously brought over and helped us use. We mixed about 3-4 gallons of concrete at a time while we added it gently into the form. I used the Quickrete formulated specifically for countertops, which cost about twice as much as the normal. I've seen what look like good results online with the regular, I'm not sure I would spend the money for the countertop version again until I had tried the normal Quickrete.

Once the form was more or less full of concrete, we removed the boards suspending the reinforcement wire and used one of them to screed across the edges to level things out on what will eventually be the bottom. I have read since then that mixing the first few batches of concrete a little wetter than the rest (until you have covered the bottom of the form - remember this will be the top of the table) makes it smoother and I will try that when I do it again. The other thing I wish we would have done is rent a concrete vibrator. We tried the whole 'palm sander on the edge' thing but in the end had a lot of small pockmarks in my surface that I think were from not getting the concrete settled enough. We solved that with a slurry of concrete, but it was an extra few steps I would have been happy to avoid.

In the dark picture you can see the lights in what will be the front edge of this counter/bar top. The back wall is planned to go up against the house so we didn't bother putting any on that side.

Step 4: Curing the Tabletop

So concrete never stops curing. Tomorrow this table will be harder than it is today. That said, we still give it a head start at hardening before we started manipulating it. We covered in plastic and let it sit for a week or two. A week would have been enough, but life sometimes intrudes so it took a couple before we were ready to work on it again. We wet the concrete a couple/few times during the curing process and covered with plastic as shown or alternatively some folks recommend wet burlap sacks. You want it to cure (a chemical reaction) without drying out, especially on the surfaces where it might cause cracking if it dries too quickly.

Step 5: Un-forming

After curing the form was removed relatively easily. We had coated the form with a thin layer of commercial mold release to help in this, and it seemed to work pretty well. The literature also describes using vegetable oil wiped on with a paper towel. I would probably recommend one of those.

Because the fibers for the lights had been glued into the form boards, many of them extended up to 3/4 of an inch out from the surface (the thickness of the form). These were cut off at the surface with a sharp razor.

The un-forming revealed problem areas. Some areas of the surface and sides had issues where the concrete had not settled correctly. My takeaway was next time, rent a concrete vibrator. In the end these problems were solved by mixing a slurry of portland cement and rubbing into the surface by hand in 2 applications with some sanding in between.

The application of a slurry took to table finish in an unexpected direction. For reasons that aren't entirely clear to me now, I was a little worried that the slurry might obscure the lighted ends of the fibers. To counter this perceived threat, I mixed a small batch of epoxy and placed a drop on the end of each fiber. My thought was that these would sand off, but they turned out to be much tougher than I expected. The epoxy spread out more than I expected, and formed sort of a bubble lens over each light, which was kind of cool if unexpected. In the end, the (likely unnecessary) decision to epoxy the tips of the fibers, as well as remedying another, much more real problem area resulted in a decision to epoxy the entire surface of the table.

Step 6: Problem Area: the Drain Board

At almost the last minute, we found some pictures online of concrete counters with inset drain boards. We concocted a plan to add one to this project. We took a pack of wood shims, and ripped 3-4 of them longways on the table saw about 1/2" wide. We spaced them evenly with the thick ends butted up to the sink and glued them to the melamine form with spray adhesive (remember the bottom of the form is the surface of the table). The goal was a relatively flat countertop with an area of sloping grooves or channels down until they drain into the sink. In the first picture you can see the shims glued down to the melamine peeking between the two boards suspending the wire. The subsequent pictures show how it looked when we un-formed it.

This worked absolutely great as far as imparting the desired shape. The problem was we didn't seal the raw, dry wood shims and so the concrete in this one area ended up being more crumbly than the rest of the table. What we hoped would be crisp 90 degree angles ended up anything but. I think the moisture moved back and forth from the concrete to the wood and this was the result. I would definitely use this trick again, just seal the shims with several coats of polyurethane or epoxy first and I think it would work really well.

Step 7: Stain

Concrete stain comes in all sorts of colors. The gray concrete color is OK, but you could have a variety of other colors by using stain. We ended up choosing a gray just a bit darker than the natural concrete. It was called moonscape or something and since the goal with the lighting was 'random starfield' it sort of seemed pre-destined. I think the unevenness of the final color is characteristic of concrete stain. I didn't expect the brownish color, but was ok with the stain color overall. You can see as we neared completion how the epoxy drops on the light fibers look like little lenses and not having intended or being particularly happy with that look led to the decision to epoxy the whole table.

Step 8: Mounting the Sink

When pouring the concrete, we had set 4 threaded rods in the concrete at the corners of the sink, extending out several inches from the bottom to allow the attachment of a fabricated mount for the underhanging sink. I used some leftover oak flooring cut to the shape of the sink with holes for the threaded rods to come through and bolted the sink to the table. In the picture you can also see I am beginning to create the frame for the table legs and making sure everything fits.

Step 9: Epoxy Coat

In an effort to hide the epoxy 'lenses' over each light fiber, we hoped putting a layer of epoxy on the whole table would make them less obvious. It didn't really, probably because we had stained and otherwise impacted the appearance of the table in between. Additionally, we wanted to stabilize the drainboard and for this the epoxy functioned pretty well. The plastic-y appearance of the epoxy is not what we were aiming for in the beginning, but that's what we got in the end. To go with the 'random starfield' look of the lights and the 'moonscape' color, we sprinkled some mother-of-pearl flakes onto the wet epoxy. Mother-of-pearl sinks into epoxy, unlike glitter which floats on the surface so we got a little bit of sparkle but maintained the smooth surface.

Step 10: The Legs

We started the countertop project without a clear vision for what would hold it up. In the end there were 4 bags (80# each) of concrete used in the countertop so 320# at least. We threw together some legs out of treated lumber, including 6 4X4 legs to bear the weight. Planning this step ahead would have been much wiser, and I suggest if you try this you design the whole project ahead of time to help plan for clearances, overall appearance, functionality, storage, etc... By the time we built the legs I mostly just wanted my workbench back so the theme here is best described as, "quick and dirty". In the same spirit I epoxied a piece of scrap treated lumber to the bottom of the table to mount the light engine to the bottom of the table.

Step 11: I Wish I Didn't Know Now, What I Didn't Know Then....

Actually, learning is why we do these things, so here is a summary of the lessons that came at some cost in additional effort or sacrificed vision:

1: Rent a concrete vibrator. If it's only $20 or $30 rent a mixer too. The work saved with a mixer is less a factor than producing all the needed concrete quickly. The vibrator might have saved us several steps which took days (mostly drying/curing, only a few hours of working) to fix.

2. Bring the light trunk out of the bottom away from any other features or structures of the table. If I were doing it again, I would bring the trunk out more parallel to the bottom surface of the table rather than the virtual 90 degrees that this one was to soften the curve from the eventual intersection with the light engine which in our application was parallel to the bottom of the table. Plan your legs to ensure you have lots of clearance around the light trunk. I might even encase the trunk in PVC or something (at least tape it as a bundle) to help protect it. about 10-12 fibers got folded hard enough to crimp and break them at some point in the project. We had actually laid out the constellation Orion in 'stars' when we drilled and attached the lights to the mold. One of the light fibers that broke was the center star in Orion's belt. So the single potentially recognizable feature we tried to incorporate had one of its iconic points fail. You would never know if we hadn't told you, so it's just a lesson we wanted to share. In a truly random application, losing 10% of the lights wouldn't matter that much. If you're trying to shape the image, random failures can be a big deal.

3. All elements of the form need to be impermeable to concrete/moisture. Using bare wood was a rookie mistake. We hope you learn from ours instead of your own

4. We made our table 2" thick. Why? "It seemed like a good idea at the time." Aside from being very heavy, the planned faucet for the sink was not long enough where it passes through the surface to attach the nut that holds it in place (really, none of the commercially available faucets have throats long enough for a 2" thick mounting surface). We're working on a fix for this. Not planning the table legs ahead of time also resulted in a conflict that will need to be mitigated before a faucet can be attached. It seems like people are pretty consistently casting concrete counters 1" thick. Getting the reinforcement wire and optic fibers in place with a 1" space to work would be more difficult, but is probably worth it. The next one we try will be 1" thick.

5. Plan the base from the beginning. Setting some treated boards into the table bottom to aid in attaching the base would have been a good idea. Or some bolts to attach the base so it could be more secure. Not to mention making sure your sink, faucet, and light fiber trunk are out of the way of your structure.

Step 12: That's It!

We hope this helps anyone thinking about trying something like this. There is lots of inspiration online. Maybe too much as we explained. Would love to hear about your experiences if you take this on!



    • Creative Misuse Contest

      Creative Misuse Contest
    • Fix It! Contest

      Fix It! Contest
    • Metalworking Contest

      Metalworking Contest

    19 Discussions

    The table looks great! It's great we can use your experience to assist in a build.

    You are my hero. This has been a dream of mine. First saw a sidewalk like this at EPCOT Center in Orlando, FL. Wow. great, great work. Thank you for sharing.

    3 replies

    Thank you! The Epcot pavers are where I maybe first saw this as well. They were definitely in my mind as I started researching. There are a couple places online doing some amazing commercial work with inset resins and/or glass as well as lighting which lent some information/inspiration as well. In the end this took some time and planning (could've used a bit more planning honestly) but it wasn't really super difficult or stressful. It was a fun project and the final result is definitely fun to sit at and drink a beer while running the grill.

    Thank you for the reply and the explanation. You detailed your successes and failures in such detail that it gives your piece that much more character. I have wanted to do this for my sidewalk. It's a grudge I have with the city but that's another story. I want to do our house number that wouldn't be visible during the day but at night.. pow! Great light show. Some questions on your piece, how did you flip the thing once it cured? Did it kill anyone? it looks humongous and menacing. I'm curious about your placement of the filament to the melamine with hot glue. Was it a small point of glue or a healthier glob? I figured the more glue the more stable the filament but then the bigger pit you'd have in your final countertop. What about drilling the melamine and placing it through? (or just a 1/4" deep). That would add way more work but perhaps better results? Maybe this is a non-issue. Great tips for getting the mixture just right. Thanks again for all the detail you provided. You've encourage one more person out in the digital universe!

    A sidewalk would be interesting. It would present different challenges, like a bigger, longer, fiber trunk. I think my filament bundle was 10' long.

    Flipping it was done with 3-4 people, very slowly and carefully. It is a beast. Fortunately I had a 4'x8' assembly table on wheels that we poured it on. Being able to roll it out of the way, was a big advantage while it cured.

    We did drill holes into the melamine form to set the fibers as you describe if I understand correctly. The hot glue I was a little worried would damage the fibers thermally, so I would squeeze a little puddle onto a piece of cardboard, dip the tip of the fiber in it, then push it into the hole drilled in the melamine. We drilled the holes all the way through the 3/4" melamine. If you look at some of the dark pictures right after we poured the concrete, you can see how the fibers on the leading edge protrude. The ones on the table top all extended 3/4" when we flipped it and peeled the form off as they couldn't be inserted all the way through because they hit the table beneath the form. The ones on the front edge of the table and in the sink well we just let hang out. Zipped to the support wire and set into the melamine 3/4", I'm not even sure the glue was necessary. My fears of the hot glue melting the fibers seemed unfounded. We had no problems with that though we were actively limiting the amount of heat as best we could.

    quite lovely aI have been thinking of doing something like this for years, I just don't have a need!

    I know you can buy a light source that will change color of light through a set pattern I am sure an Aurduino person will come up with one so you get waves of color, but if you split the finers up so random lights are in new groups you place the diode infront of each group. They will all cycle, nut they will do it all over the surface and each diode emitter will not be syncronized so the pattern won't show. If your Orion held up you could have made that one all white except for Betelgeuse, which needs red,

    There are many concretes out there with lots of additives which make it ok to be thinner. Chen comes to mind.

    But honestly this looks sweet as is.


    1 reply

    Need?!? I think everyone needs a 320# outdoor table that lights up.

    Individually controlling the color of different bundles would be cool. I'm not sure how best to do that. This uses a 'light engine' that looks like a projector of sorts and the color is all or nothing across the entire trunk of fibers. I don't think with this you could have some one color and some another. Using LED's and a controller instead of fiber optic or as the light engine(s) might give you more options, but I can't offer much in experience or expertise on that idea.

    So I have been doing concrete casing on a small scale myself recent, not for a counter top, but custom paving slabs, after the first test one I can confirm a way of shaking/vibrating the air out of the concrete results in a much better finish as my subsequent casts had a really nice smooth finish, but the first one I tamped down with wood and that didnt work well. I was literally using just basic cement, sharp sand and 6mm stones, for the most part I havent seen a single stone come to the 'surface' but the stones apparently add to the overall strength. Something else I couldnt see you touch on that might be worth investigating is actual cement dye rather than stain, its available in all colours(including black!) and varying the amounts might have given you a more cosmic look :) I'm trying out buff,brick red and khaki green, you do need to do a few trials of colour first to get the 'receipe' right. You add it during the mixing stage so it colours the entire mix, I have considered mixing different colours in separate batches and adding them to the final mould to make a multicoloured cast with one consistent concrete batch, some ideas for your next project perhaps?

    1 reply

    Thank you. I will definitely consider mixing dye as a possibility and yes, though I've never tried it, I am now a firm believer in using a concrete vibrator when casting into forms.

    great job! the fiber put in the proyect an amazing touch!

    Looks fantastic, my suggestion would be to make it 38 mm or an inch and a half thick, one inch, 25.4 mm seems just too skinny to me. (I'm an old builder, from OZ).

    Maybe bundling the fibres in groups of 10 to 15 tying to the reo and then splitting the bundle close to the exit point may help stop the kinking.

    1 reply

    Thank you. I certainly don't think I could do it any less than 1", but you may be right about 1.5". I've had to move it twice now and it is a beast so my next experiment will be how thin/lightweight I can do this.

    I'm not sure we lost any fibers that were inset in the concrete. It was right where they emerged from the bottom that maybe a dozen of them broke. You can see them in the picture. That was about the time I noticed them, the table had been flipped at least twice by then. I actually bought some 'splicers' for fiber optic on amazon but they were for a larger size of fiber and never really worked plus they were heat-shrink so I was a little nervous about putting a lot of heat near these plasticish fibers, 90% of which were working.


    This is exactly what I was looking for!

    In your research did find if anyone sanded the countertops with the fiber optics set in place. I have seen some concrete counter tops sanded for a polished look.

    Would you recommend staining over buying concrete coloring?

    What size holes did you drill for the fiber optics?

    Looks great!

    2 replies

    I did sand this table with the optics in place however, I had put a drop of epoxy on each one. Sanding concrete (and I just used an orbital electric sander - I understand there are beefier ones and special discs but I used a standard 60 grit I think was the roughest pad I had) is pretty slow going and I can't say it did a lot to the finish.

    I used stain, so I can't speak to mixing dye into the concrete. Stain worked well and had few drawbacks I can think of so I would choose it again unless I wanted to experiment.

    The holes were tiny. I broke 2 or 3 of the smallest bits in my set drilling the 150 holes. The fibers are 0.75mm diameter according to Amazon which is about 1/32 of an inch. They weren't exactly snug, hence the hot glue gun to stabilize.

    I hope this helps...

    Nice work. Looking forward to version 2.0!

    Amazingly inventive use of lights. This must look amazing at night. Thank you for sharing this.

    I was pretty happy with how it turned out. Clearly, I learned some things along the way and have been somewhat itching to make another one using the things I have learned. I think the next one will be an outdoor dining table for the deck.