Electric Chair




About: I am a glass sculptor with a shop and gallery located in the Manayunk section of Philadelphia. Besides being a dad and running my business, I have a strong interest in electronics, and physical computing.

An electric chair AND LEDs, oh my. However, this instructable  is more about a demonstration on the coefficient of thermal expansion between different materials. Before I lose your attention, did I say that there was going to be molten glass, LEDs, AND an electric chair ( in this case, a small chair like object with current running through it).

I am encasing a very, very simple circuit in molten glass that brings up a few interesting things:

1. Glass is a conductor when molten, something you do not hear about too often in your electronics books, but then again, how often does this situation come into play.

2. Glass is an insulator when not molten, though  technicality speaking glass is never completly solid. The molecules are still ever so slightly moving, meaning that your kitchen glass will eventually slump. However, this slumping may take a couple thousand years to do that.

3. Copper can be combined with molten glass. This ia a loose statement with way too many parameters for why this can and cannot work.

If you are inclined to get your geek-on, I will put a bit more info on another page in this instructable about the science behind combining these materials in this situation.


Step 1: Making a Simple Circuit With Copper Wire


I used copper wire that was twisted and crimped to make part of the simple circuit. Since this will be encased in 2000 degree molten glass, I am pretty positive that solder won't hold up too well.

I am just guessing, but things like IC chips and mosfets won't hold up to 2000 degrees either.

I did not want the copper too thick because there is a good chance the glass will crack. This will be explained later.

Step 2: Time for the Hot Glass

This is a series of photos showing one of the ways I tried to encase the copper wire form in glass.

The video clip is part of another method that I had tried.

Step 3: Quick Side Note

Some quick geeky technical info about all of this. All materials have property known as coefficient of thermal expansion  when subjected to heat and cold. This is the rate that materials expand and contract when heated or cooled. This rate is measured using some really glazed-over math formulas which I would recommend Wiki for the info if you are so inclined.

Now, every material like copper, iron, glass(depending on the formula), etc, have different coefficents. If their coefficients are close enough, then they may be compatible. If their coefficients are too far apart, they will most likely be incompatible.

There are probably hundreds of different glass formulas and most are incompatible with each other.

Normally, just tossing random materials in hot glass will cause the glass to crack when it cools.

The copper wire that I am using is just compatible enough with the base glass I am using that there is not a problem with cracking.

That being said, a large chunk of copper or very thick wire may crack the glass eventually.

Step 4: Finishing the Simple Circuit

Other then showing a few construction photos, I will not go into how to wire and power LEDs. There are tons of instructables that focus on that.

Step 5: A Few Last Photos

This page has a few photos and video of another copper circuit encased in glass. This has got a little art nouveau  feel to it.


Runner Up in the
LED Contest



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    11 Discussions

    Really old church windows show how hard glass is still fluid. You might have to come to Europe to see some old enough. They are way thicker at the bottom than at the top now.

    Love the result of this instructable. Too bad i cant melt glass in my kitchen ;) do you think this might work with other clear materials? Maybe there's some acrylic stuff thats suited for home use?

    4 replies

    Well, zag1024 was right with his comment based on recent research. The belief now about church windows being thicker has more to do with how they were made. However, even the Corning Museum of Glass had an exhibit showing glass that had slumped over time. But hey, Pluto was still a planet a few years ago and now its not.

    As far as doing something with cast acrylic, YES. In fact, I wish I had thought of that as an alternative if someone does not have access to a glass studio. You have many more options since you won't be dealing with extreme heat.

    I was just trying to demonstrate the possibility of combining a working circuit with hot glass. Using LEDs then takes advantage of light and glass.

    I have never done anything like this, but I really like how it works and especially how it looks. Much prefer the "artsy" one further in the instructable.
    Could you link me to a shop with the kind of acrylic (or other) stuff that I could use at home? Not quite sure what to google for, especially not in English ;)


    If you google ' casting resin ', or ' clear polyester casting resin ', tons of info will come up. I should point that resins can be dangerous to use like acrylic. The polyester resin that you can find at your local craft supply store like A.C. Moore is probably your best bet to start with. It is called ' Castin' Craft Clear Polyester Casting Resin '. You will need lots and lots of ventilation when you use any resin.


    Reply 8 years ago on Introduction

    technically, no. That would involve nuclear fusion, and I am saving that for another instructable when I get it worked out.

    In the video, you can see me pressing a switch. That switch is connected to batteries inside the box.


    8 years ago on Introduction

    I don't work with glass, as you do, so I may very well be wrong, but according to wikipedia, it is unlikely humans will be around to see our kitchen windows "slump" - the amount of time predicted by one journal suggests that it would be longer than the age of the universe! Apparently, the increase in thickness at the bottom of old windows is caused by a manufacturing technique rather than the glass flowing over time. See http://en.wikipedia.org/wiki/Glass#Behavior_of_antique_glass.

    1 reply

    Reply 8 years ago on Introduction

    After reading your comment, I did a little research. I was off by a few dozen zeros on the time line, but it can still happen. Back in the day when I learned about it, that was the consensus. I haven't stayed on top of the latest research, so my bad.