All right, everyone welcome back to Cody's Lab. So today
I'm going to be making some soda lime glass which is of course the most common glass that you'd encounter in everyday life in things
such as window panes and glass bottles.
It is called soda lime glass because two of the main ingredients are sodium carbonate or soda ash and
calcium carbonate which when you heat it, it forms lime. The main ingredient, which you probably know of course is
sand.
This right here is the purest, whitest quartz sand that I could find there's very little impurities
It's essentially pure silicon dioxide and the small particle size means that this will melt quickly.
This is exactly what you're looking for when you want to make glass.
But you may have noticed those are not the only ingredients. Most recipes that you find
only list the main three, but there are many different types of fining agents
that is used in glass making. I've got four here that I'm going to be using today.
This is potassium nitrate which is essentially high temperature bleach.
It's an oxidizer and it burns out impurities in the glass thus making it clear.
Some Magnesium sulfate which form sulfur dioxide gas as well as
acting as a high-temperature flux. The sulfur dioxide gas will help collect together other bubbles together and
bring them out of the melt. I also have some alumina or aluminum oxide this increases the chemical resistance of the glass.
And over here. I have one that you might think is a little odd. This is antimony
This is a replacement for arsenic. The arsenic oxide or antimony oxide in this case also helps remove the bubbles from the melt.
Okay time to weigh out the ingredients. I'm going to start with 7.3 grams of silica sand.
Just weigh it out here with my precision scale.
Probably don't really need to go out to this kind of precision because really there's quite a range of what will actually form glass.
so
7.1...
7.3 excellent
Now I'm going to need approximately one gram of calcium carbonate.
This very fine calcium carbonate powder by the way is actually chalk. Not the sidewalk chalk
This is actually the chalk that is formed by
animal remains settling out of the ocean.
Microscopic shells and stuff. Now for the soda ash
I'm going to need one and a half grams of this.
The soda ash, which can be extracted from trees, this stuff came out of the Great Salt Lake, but
this lowers the melting point of the glass and makes it workable.
The lime makes it so that water doesn't dissolve it because just the sodium carbonate and silica together is water soluble.
So I'm going to need approximately .1 grams of aluminum oxide.
Not very much and about the same amount of magnesium sulfate.
That already brings me up to my target of 10 grams but
I am going to add just a tiny amount of the potassium nitrate and
An even smaller amount of antimony.
Okay
That should just about do it.
I think I went a little over on the antimony, so I'll just add in just a little bit more potassium nitrate to compensate.
That should do her.
So here's my rough glass mixture. I'm going to transfer it over into this little ceramic dish. Now this isn't the ideal crucible
I think it should work
There's a chance that the glass will actually dissolve the ceramic and it certainly will dissolve this glaze.
I'm not entirely sure what that glaze is made out of but I don't think it'll hurt it
it might make the glass a little bit cloudy, but
you guys will still get the point.
I of course can't use graphite crucible because the graphite will dissolve into the glass with carbon resulting in a product which is
it'll be black or some off-color. This is not really what I want.
So here is my little metal melting furnace which I've used in many videos previously. Now this thing gets up to about
2,000 degrees Fahrenheit or
that many degrees Celsius
Which is unfortunately about 500 degrees Fahrenheit
shy of what I need to actually melt glass.
That's where this microwave comes in. I'm going to use this to finish it off
but for now this guy's job is primarily to decompose the calcium and
sodium carbonate into calcium and sodium oxide
That'll start around 1600 and should be fully complete by the time it reaches 2000. So most of you probably know that glass
does not react in a microwave. I mean this glass platter in here for instance. If it did react this would be a problem. [Glass shattering]
Also, you might be able to notice that the glass window on the front of the microwave has a metal screen to keep the microwaves
from going right through it, and that's all true. Glass is completely transparent to microwaves unless
It's melted. See, glass is
An ionic liquid. It
conducts electricity and you might know that when things conduct electricity in the microwave they get hot and start fires.
But hopefully I can control that and instead of starting a fire I'll make some glass.
So unfortunately my other furnace is still mad at me for leaving it outside in the rain.
So I'm switched over to this other furnace here and also a slightly different
melting dish for this alumina foam
block here, okay, the furnace is at
1720 which should be hot enough to driven off most of the volatiles.
so
Let's take this set up... now see if we can turn it into glass.
Ooo that's warm. OK.
So it's already mostly liquefied that's mostly the sodium carbonate has melted and has formed sodium oxide.
Let's cook it.
Microwaves is keeping it hot.
Looks like it's getting hotter too.
That's exactly what I want.
I'm going to have to keep it hot for a fairly long time so that the bubbles have time to come out of the mixture.
So I'll come back in about five minutes and I'll see how it's doing. Let's see what we got in here.
It's very hot.
Looks like it is glass, but it's still full of bubbles.
So I think what's going to have to happen here is I'm gonna have to run this microwave for a really long time.
Well, let's get to it.
Let's try...
30 minutes.
So what's happening here is the glass, when it's a liquid,
the ions are free to move about so it conducts electricity
and that absorbs the microwave radiation thus causing it to heat up.
Doing it this way. I can achieve much higher temperatures because the heat is more concentrated that I can achieve with the furnace
Look at it go.
So it gets hot but not hot as I need it to get so let's set this over top of it to add some insulation
Hopefully that will work.
So the microwave seems to have stopped heating the glass either
I've ruined the microwave or there's some sort of high temperature shutoff.
So it's not producing any more microwaves
Which means this is now cold. Let's
put this over in the furnace here, so we don't break the glass. I guess I'll let the microwave cool off and we'll see if
we can take another shot at it. All right microwaves back on line. So it was just overheated.
What I think it's kind of interesting is it looks like you've got two spots on either side of the glass puddle which are hottest.
It's almost like a line drawn between them
I guess that's because it's generating an electric current between those two spots.
I'm probably going to put the dish over top of it to insulate it again
And then we're going to run it for as long as I can.
And this will probably be as far as I'm going to go. OK sounds like the microwave shut off again.
Oh and I broke my little dish, but look look at that! Isn't that lovely?
Now that it's mostly cooled down to room temperature. Let's see if we can pry out a big piece of this
glass. Ah, looks like my brick broke. That's all right, I expected it not to survive.
There's a piece of glass right there.
See if I can clean it up a little bit, and I guess we'll try to remelt it
form/make something out of it.
One problem I've noticed using the alumina is that around the edges and on the bottom
some of the alumina actually dissolved into the glass which made it extra viscous.
So the bubbles were even harder to get out.
But there you go.
So here's the plan: I'm going to soften it to the point that I can cut it and move it with a knife and
hopefully it sticks to the ceramic here, and I'm going to like scrape off the clear glass using this knife.
Can't really melt the glass with this torch, but I can soften it.
Looks like it's stuck.
see if we can
work it off
Oops. Know what this is? This is a knife vs. red-hot glass. [laughs]
There it is. I burned my glove on it.
So that's something.
Let's quickly put that back in the furnace so it cools slowly.
So there it is! I've managed to cool off my glass bead without it breaking.
And look at that. I've also put it on a chain so that it can be used as a necklace.
and
It is a little bit cloudy; there are still some bubbles and some alumina that didn't dissolve into it
but as you can see
It is clear.
Light still does pass through it.
There you go.
Someday, I'd like to make a larger piece of glass straight from sand, perhaps a glass bottle or even a window
but for that
I'm going to need a much better furnace and in fact there's some rumors going around that Grant Thompson is building such a furnace and
there's a planned collaboration between
him
Make Everything and I to see if we can do just that so
Hope you guys stay tuned for that; I'll see you then. In case you're wondering
this class is completely insoluble and should be safe to eat off of.