Over the past few months
I've been working on this video as a follow-up to user comments on a previous video on if it's possible to cast obsidian.
This proved to be a major challenge that took six attempts, broke multiple crucibles and two different kilns.
But I didn't want to stop until I finally had success at casting obsidian.
Previously I made obsidian blade by knapping, which is kind of a Stone Age technology.
But a lot of people wanted to see me try and do actual casting with obsidian.
Which is something that's pretty difficult because actual obsidian doesn't melt until over 2,000 degrees Fahrenheit
Which is something that's very hard to achieve.
So while looking for this I realized that you can actually cast glass using sand and a similar method that I used for the aluminum
But because I can't melt the actual obsidian,
I need to grind it up into small little particles,
mix it with the flux and then melt it. And hopefully then I can cast it into some form of knife
Obsidian is largely made of silica like regular glass but also has an unknown mixture of other impurities in it as well.
That can make its melting point difficult to work with. Melting straight obsidian is potentially possible
But would likely result in a very thick viscous substance
That'd be hard to work with especially to cast
my early attempts at glass making also had a fair amount of impurities which made it really difficult to work with so
The solution to this is flux
Which is adding chemicals with lower melting points that make the entire solution melt easier and be fluid enough to cast
so the thing with knapping is that when you fracture it you're able to create potentially razor thin blades that are a
Molecule thick you. Can't quite reach the same sharpness by just sharpening glass itself
But you should be able get something close and it's also probably gonna be pretty
Brittle as even this is brittle itself and it has wood reinforcing and holding it
So let's give it a shot. First up is grinding the obsidian, melting it down and see if this is even feasible
I used a ball mill to grind it to a fine powder in a liquid solution, which I then need to boil off.
One of the biggest pains is getting a crucible
That's just big enough to hold a large enough volume, but still fits inside the rather small kiln
As it heats the Obsidian and flux tend to boil over some and unfortunately in these smaller crucibles nearly everything spilled out
For this first test it looked like the Obsidian and flux may have separated, which means this might not be feasible
Also enough spilled out and burned through the insulation until it broke the kiln's coil making the kiln unusable
Next I tried a larger batch using a more flexibly designed kiln that I could scale up to fit a larger crucible
(whispered) I uh, suck at this
It's melted all the way through.
For an initial small test knife
I carved a model out of styrofoam and then packed it into the sand
Once poured the hot glass will burn off the styrofoam and fill in its place
Like regular glass, if my cast obsidian cools too rapidly it'll fracture and shatter
So I took a note from the compound we used when we made glass with Grant last year and picked up a bag of vermiculite.
Which can act as an insulator to allow the glass to slowly cool
Alright, lets give this a shot.
Unfortunately that wasn't enough and it still ended up shattering
But the most interesting result was that the remelted obsidian turned out fairly transparent with just a slight amber color
This is likely due to the flux which probably added to the transparency
But this also might be related to how this glass is formed versus the original obsidian
Which raises an interesting question on if this compound could even be considered obsidian anymore
Regrinding this glass, I started a new batch, but this time, assuming it got more clear because of the flux
I thought I'd attempt to counteract it by adding some new impurities back in
specifically added in some metals that are often used in glass making to dye glass black: nickel and chromium
Which gave it a nice dark color very similar to what it started with
Now to cast it. (talking about fluffy cat) Usually she just lays in the grass and eats it.
So I'm gonna try and cast this toy Roman sword in obsidian but I don't want the handle to be obsidian
So I'm gonna cut that off
Unfortunately by the time it came to pour it, my crucible had cracked and the majority of the obsidian had leaked out
While I reset again for another attempt I was curious to do another experiment to see what would happen
If you try to melt just straight rocks of obsidian
This resulted in a interesting formation of a foamy mess
Likely caused by off-gassing of compounds like water that'd previously been trapped in the obsidian
The semi molten obsidian adhered to the crucibles as well as the sides of the kiln which unfortunately caused this kiln to break as well
But in the interim I had fixed the first kiln and gotten a better fitting crucible. So let's keep going
Collecting as much of the previous attempt as I could
Plus adding some more crushed obsidian
And some more flux I'm ready to go again
This time with a very promising pour
Alright, moment of truth to see if the sword is in one piece
I've had mixed results so far with the vermiculite of
Some things still shattering in it, some things not
Let's see what we got
Dreams shattered dreams
Refusing to give up
I brought my setup to glassmaking studio FOCI
Where I could throw my final result into their annealing chamber and not risk it shattering
Okay, so got a weird reaction in the last attempt where it got really bubbly when we poured it
not sure exactly why, there might've been some cracks that formed when I transferred the mold or
There might have just been more humidity in the air that made it damp and caused a reaction
I'd like to polish this, it'd probably break up if I try to grind it and shine it up. So
We're gonna go over there. Give a one more shot to do it the right way previously
I added a little bit of a tang to attach a handle to it easier
But that's kind of flimsy so I'm a little worried how well that'll hold up. So I think I'm just gonna do the whole thing obsidian,
So I'm just super gluing the handle back on sand cast it once more I hopefully will finally have the obsidian sword
Not very strong
Working with FOCI, I learned how sand casting for glass is done a slightly different way
Instead of packing the sand tightly around the mold you lightly place the mold into the sand and pack it only along the edge
The idea is to allow the air to escape through the sand so it doesn't bubble up through the glass like it did last time
Then they also torch the sand to leave a fine layer of carbon on top. So the glass can better release from it
So after six attempts, I finally managed to cast a full obsidian blade. Unfortunately in the annealing process it got a little cracked and
Probably can't polish it off and put a nice edge on it, unfortunately
I took quite a bit of flux in order to make it cast-able which made it a bit difficult to actually temper
It's kind of messed up the whole annealing and made it a bit weaker, so it's more ceremonial at this point.
despite all the mythology around obsidian, it's really fragile, just glass and uh...
So put it through a whole different process than how the obsidian originally formed, which is evident when it became pretty
transparent at one point and then I had to add the additional dyes in order to turn it back into black. So it's
kind of debatable if this is obsidian, but it's definitely made from obsidian
and uh,
took a lot of attempts, though I finally made it
So this took six attempts and
broke two crucibles and two kilns. Just fixed this guy and last time this crucible cracked it leaked the obsidian all over it and
Eroded and did a ton of damage
Fortunately, it's still working at this point
But I don't want to push my luck too much so as much as I enjoy making unprofitable videos and I'm gonna call it
at this point
say it's complete
So now that I've cast the glass next I'm gonna move on to a different mineral, actually try and do
actual metals with some copper and make bronze
So I'll do that in uh...
In a while
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