Introduction: DIY Light Transmitting Concrete (+ HD Video)

Picture of DIY Light Transmitting Concrete (+ HD Video)

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I'm going to show you (as best as I can) how to make light transmitting concrete. Google it, and you will be amazed at how beautiful it is! I was desperate to get my hands on some...but considering the cost, I decided to make some with stuff I already had around.

This material has the strange effect of looking shiny or sparkly...but it's dull concrete at the same time! It's very entertaining to show off or play around with.

If this material interests you, check this article out:

Here is the HD video:

Here is the normal video:

Step 1: Making the Mount

Picture of Making the Mount

 You need to roll some polymer craft clay into a flat circle. Make it as level as possible.

Step 2: Making the Mold

Picture of Making the Mold

 I cut out a ring from a spray paint can lid...anything that is waterproof will work. After you cut it, press it into the clay.
The whole point of this is to make a mold to cast the concrete into.

Step 3: Fiberoptics

Picture of Fiberoptics

Get one of those plastic fiberoptic toys. They have that sort of 'frill' of glowing wires...see the photo :)
Cut a bunch of small 1 inch segments by breaking off about 10 wires from the bundle, and cutting them short en masse.

Step 4: Placing the Fibers

Picture of Placing the Fibers

 Stick the small fiberoptics you cut short (in the last step) into the polymer clay. This may take awhile...but it's kinda fun!

I used pliers. If you use them,too, be mindful not to crush the fibers...they are quite fragile, even though they are plastic.

Step 5: Pouring the Concrete

Picture of Pouring the Concrete

 I used Rockite Floor Leveling Cement. It's realty just super-duper's more durable and looks way cooler. I even think it's finer grained than plaster (and takes on finer detail. Unfortunately, it doesn't take paint well).

Mix the concrete pretty do not want air bubbles.

Step 6: Breaking the Mold

Picture of Breaking the Mold

 Once the concrete is cured (2 hours?) pull off the polymer clay and cut off the plastic ring. The concrete will not stick to the fact, it's practically repelled by it!

Step 7: Trim the Fibers

Picture of Trim the Fibers

 After you let the de-molded concrete dry out over night, cut off the extra long fibers. I used finger nail clippers to pick them off :)

Step 8: Polishing

Picture of Polishing

 Use sandpaper to polish your new piece of light transmitting concrete! the effect is quite strange...sort of alien feeling. Light, even colored light, is able to pass right through and create a pixelized likeness on the opposite side...!


Gerraldinho (author)2016-10-03

i made lightconcrete some years ago, but during the polishing it broke the concrete around the fiberoptics... Furthermore the fiberglassstripes came out of the holes... :/ How you fixed this?

Ali-Kazemian (author)2016-07-07

Many thanks for this interesting project.... The videos are not shown though, can you provide me with a link that I can watch the videos? I really like to watch them.. thanks

DisplacedMic (author)2014-07-20

wow, that's really terrific!

Travpena (author)2013-12-15

im going to take this technique and make constellations with different shapes and the sort, thanks for the idea

Ogredude (author)2012-04-07

This is an awesome instructable!  As soon as I saw it, I knew I needed to do a project with this technique.  But what to make? One of my friends owns a concrete supply company, so I put his logo in the concrete. He was very happy to receive it as a Christmas present!

I ended up having to make this thing twice. The first time, I really messed up the water to concrete ratio on the mix, and when I tried to demold it, it was very crumbly and pretty much fell apart.

I took photos of the construction of the first one, but didn't photograph the second one until it was complete. I learned quite a few little techniques on the first try that made the second attempt go much easier, so I'll describe those techniques as I go.

I started with the clay base. Then I printed his logo in black on my HP inkjet printer, cut it out, pressed it onto the clay, then wet the back of the paper and dabbed it a bit with my finger. HP inks are water-soluble, so when you peel the paper away, it's transferred enough ink to see what you're doing onto the clay.

The second time round, I decided that was still too hard to see, so I filled the design in with Sharpie. This helped a bunch.

I started putting fibers in one by one with plastic tweezers, but the fibers are so low-contrast that I had a very hard time seeing where they were going and where they needed to be.

So I used a highlighter to color about the last quarter inch of the fibers, and worked under a blacklight, and I could see what I was doing just fine. The inked part of the fibers ends up in the clay, and it doesn't bother the finished piece.

I also discovered that an incense holder makes the perfect staging area for fibers, the ash trough makes it very easy to pick them up individually with the tweezers.

After it was cast (and I fixed a crack with epoxy), I polished it up as best I could on a disc sander (killing 2 discs in the process), and covered it with several coats of triple-thick glaze.

On one side is random dots of light...

On the other, a logo!

nepheron (author)Ogredude2012-04-10

Hey that turned out great! What kind of fibers did you use?

Oftentimes, crumbling happens because of too much water. In order to get regular concrete thin enough to fill the spaces around the fibers, it's too wet and cures strangely. Rocktite is really magical stuff, you can't add too much water. It pretty much cures no matter what.

A secret I learned from casting lots of stepping stones is that once you open a bag of concrete, you have to either use it within 24hrs, or put it in an airtight garbage bag and seal it really good. Old, opened concrete will pretty much crumble no matter what you do with it (absorbing water in the air reacts the lime in the micture)

Rocktite seams to work fine even if its left exposed for a very long time.

Ogredude (author)nepheron2013-01-16

Oh man, I forgot this comment was even out here!

The fibers I used were from an LED fiber optic lamp I found at the dollar store. I snipped them to length with scissors.

I presented this piece to the owner of the concrete business, he really enjoyed it.

He gave me some tips on working with concrete. Firstly, concrete will always shrink a bit. If you don't want your piece to shrink, use non-shrinking grout mix instead. (he gave me an 80lb sack, yay!) He said it probably crumbled because I put too much water in. The grout apparently doesn't have that problem, you can mix it thinner if you need.

shaoran18 (author)2012-10-27

Thank you for posting this

Probedude (author)2012-08-18

The most beautiful fiber optic in concrete art I've seen is by the artist Clyde Lynds.
First saw an example of his work back in '88. Looks like he's gotten more sophisticated.

redorchestra (author)2011-08-18

just to add a similar idea I recently heard.
My Cousin is in Peru helping villagers to add sky lights to their huts. They use a clear plastic pop bottle filled with water (clorinated to keep out green stuff)
It is embedded in the ceiling and sticks out of the roof. It channels sunlight into the hut and apparently lights up as well as a 60 watt light bulb. As long as the sun is shining!

Thaikarl (author)redorchestra2012-03-24

here's the link to the project. i made one for our shed here in thailand, it's so simple but works wonderfully!

erronius (author)2012-01-17

My friend Karl (KRЯRL to the rest of the world) and I have started putzing around with fiber optics in a fine concrete or mortar. KRЯRL scanned a small relief his friend made from one of his unique figure drawings and had the scan printed into a large styrofoam (polystyrene for the Brits?) negative. The styrofoam served as both a mold for the concrete and a soft substrate to poke the optical fibers into.

you can read about the process on Karl's blog at:

Oscelot (author)erronius2012-03-19

Nice project!

Rienei (author)2012-03-08

Hi, may i know if the following 2 works :
1) Sticking the fibres into the concrete AFTER pouring the concrete into a mould,
2) having less space in between the fibres to allow more light to pass through

Thank you in advance :D

Oscelot (author)Rienei2012-03-19

I doubt sticking the fiber into the concrete afterwards would work too well, you'd get concrete on the ends and end up with it looking fairly dull, in my opinion. I don't see why you couldn't stick as many fibers in as you want to. Just my opinion.

chibisuke11 (author)2011-08-20

can i use white cement? please reply ASAP :)

erronius (author)chibisuke112012-01-17

You may want to try to find a book called Sculpting With Cement by Lynn Olson. He uses white cement extensively on the outside of his concrete sculptures

DeeRilee (author)2011-12-14

I think I might try making the "bowl" of a birdbath this way! It might make for some interesting sparkles of light on the ground surrounding it! (hopefully!)

josephlebold (author)2010-12-30

I must say out of the hundreds of decorative fiber optic devices I have never seen glass fibers used. They would be too fragile.

real fiber optic cables use glass fibers

yeah I know, they use fake fiber optics in the fiber optic christmas trees and anything one can purchase at a store with fiber optics.

badpanda (author)2011-08-18

Glass fiber optics would not be too fragile for this application, but they aren't likely glass fiber optic because it is too expensive for use in a toy that doesn't actually need to carry any kind of data, and for a toy like this the attenuation would not be a critical factor... attenuation is a measurement of how well the fiber transmits light. This is most likely POF or Plastic Optical Fiber, not the common silica based type used in telecommunications applications which is glass, and just about as flexible as the POF. (I worked for Lucent doing Dense Wavelength Division Multiplexing stuff for a few years, Google it :)

pbecker83 (author)2011-08-18

Pretty neat. I'd like to see some night time video.

LMas (author)2011-08-18

Really nice project!!!!

DiscoInferno (author)2011-08-18

Oh my... "Light" project are always interesting.

erronius (author)2011-04-24

LOL: agggh! another excuse to make a variant of the infamous Austin Powers Tent Scene!

Here are a couple other things i was thinking abewt:

1) if you want uniform light transmission, maybe one could use a mesh or some such thing to distribute the fibers evenly over the surface.

2) Well, what about non-uniform light transmission????!!! Sounds like something with real potential to me. What if you varied the density? You could create areas of gradient,highlight or shadow or an entirely new design or swirly pattern within your piece, which could really add an interesting dimension to a sculptural piece that was a low- or medium-relief.

tgrundle (author)erronius2011-08-18

you could also leave the extra length on the fibers and use something (like paper or thin cardboard) to block some of the fibers from others and using led's light different sections with different colors. this could make a great yin-yang effect with the circle that was made in this ible.

wobbler (author)2011-08-18

Instead of making the clay into a flat circle, you could first make it into a long square profile strip. Then place your fibre optics all along the length of one side on the top surface. You wouldn't need to push them in, simply lay them on the top, so it should be quicker. You could then lay another long thin bit of clay on top to hold them if needed. This could then be rolled up to create a spiral. Alternatively, you could lay this out in a shape and then fill in the gaps with either wax or more clay before pouring the concrete.

phapboy (author)2011-07-06

SO COOL! Now I wanna see someone mash this project and this project!

MissCindel (author)2011-05-16

I like the image as it is held up to the light ... and started thinking that the fiber optic strands could be assembled in the clay in a pattern too :*)

erronius (author)2011-04-24

So you used an amended plaster, like hydrocal or ultracal? That's pretty interesting. Looks like you could do any kind of piece that has low relief.

You know, if you want to color the material, you don't necessarily have to use paint. You could conceivably use a colorant, like iron oxide (or one of those marking powders they use for carpenter's chalk lines, some of which are iron oxide) or a mason stain (sold at ceramics places) and mix it into your goop. If you are using cement, you can make it brighter and less gray by using white Portland cement instead of the ordinary dingy gray variety.

Broom (author)2010-03-30

I'm suddenly thinking of a concrete countertop, lit from below! OK, it won't be bright enough to see by, but super-cool accent lighting. Or - the most awesome bar counter ever!

rubyintherough (author)Broom2011-04-04

Did any of you ever do the glass in counter-top?
I'm searching for a way to clean up the crushed glass from the recycling center to use. It's got too many label bits stuck to the glass.

Broom (author)rubyintherough2011-04-11

Put the glass in a roasting pan, and cook in the oven at the highest temperature (clean mode, if you have it) for an hour or two. The labels will turn to ash.

Valster (author)Broom2010-05-03

My tropical theme bar is finished except for the counters...  Remote light wheel with color change or twinklie effect?  Waves, palm trees, tiki head patterns?  The possibilities are endless!

alin.sala (author)Valster2010-07-08

making the top of the counter from concrete with fiber optics incorporated like in this tutorial but insead of cutting the fiber short connect them as bunches to a light source, like a light engine with a controller and you can make your bar rock!!

nepheron (author)Valster2010-05-04

 This may be a bit out of your price range, but putting an LCD screen underneath this stuff looks amazing! The colors are pretty crisp, but 'pixelated' so a large design would be necessary.

Moralito (author)Broom2010-06-08

Bar counter is the way to go....Simply awesome...

nepheron (author)Broom2010-04-01

I think there would be enough light to see by! There is very little loss in the fiber optics.

Broom (author)nepheron2010-04-01

Not the point. The light is coming from below, making everything on the counter backlit, and therefore (I bet) darker by contrast than if the counter weren't lit.

Valster (author)Broom2010-05-03

Broom, I just realized how awesome drink glasses will look when lit from underneath.  I have to do this!

drakesword (author)Broom2010-04-07

If you placed it on the vertical edges then you would be able to see the edge in the dark. Keep you from bumping into it at night!

itwasalan (author)Broom2010-04-01

It would be really cool if the fibre optics could cause glass aggregate in the concrete to glint or twinkle too.  I was going to do concrete counter tops in my kitchen anyway.  Time to do some proof of concept experiments.

drakesword (author)itwasalan2010-04-07

what about a layer of fine crushed glass on the side facing up?

I made some fine crushed glass with a capped steel pole and a baseball bat. Just pound away until its like a dust.

hishealer (author)Broom2010-04-02

 Not only that, but you could spell out Welcome or make pictures with the "pixels"...

tanmanknex (author)hishealer2010-04-05

Combining that with mrfusi0n's idea above, that would be really cool.

dfc849 (author)Broom2010-04-01

afroray (author)2011-04-04

thank you so much now i have a experiment to try out :) also a quick question do you think this would work if i use plaster of paris?

nepheron (author)afroray2011-04-09

Thanks! Plaster will work fine.

sith_gundam (author)2011-01-05

This is not real translucent concrete, it's just a mix of ceramic glue and optic fiber.
The true litracon (or a near version) uses a mix of fluorite, cement and fiber glass.

About This Instructable




Bio: Travelling since 2013. I'm currently in Australia for some reason. --- I’m Calvin Drews, and I love to learn, experiment, invent, create, repair, and ... More »
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