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in which there is fire!

Five minutes before the housewarming, it was an unmitigated disaster. We had trouble getting the regulator on our last-minute oxygen tank, cooking half the food we wanted to, the firebrick for the furnace had cracked, the copper ore was lost in the mail, the interplanetary magnetic field chose to deny us the auroras we'd been hoping to show our guests.

Five minutes after the housewarming, there's a line, like ducklings, of homemade misshapen shotglasses on the windowsill. The furnace is full of melted copper in knobbly coral growths (even if we don't know it yet), the whole house smells like naphtha and cryptocrystalline and corn roasted in the smelting furnace, pumpkin curry and smoke.

Pictures (of which there are very many) are by either wazm, flicker site or caladri, gallery, or robogock, whose gallery is here.


Here is small-scale glassworking - a bead formed by dabbing molten glass on a bicycle spoke. There's something really satisfying about teaching people glasswork. The thing about glass is that it all looks about the same when honey-molten. So you can't tell exactly where a particular piece or color is when you go to add more. It might be here, it might be there, so you have these two possible beads, ghost beads, you're making, and then you add the next color, and maybe it's here on top of this one, or over there, or right here... and now you have six ghost beads - you won't know which you made until it's cool, and every motion, every heat, every color just adds more, some teaming crowd of possibility in scarlet and silver foil.

Instead of shepherding one shape, one set of colors, it's like you're changing the shape of which are possible and which aren't. It's about trust and intuition more than control. Everyone deals with that differently, and it's lovely thing to watch.

Here is the nifty bead made by robogock.

And here is the big torch. It takes an oxygen tank.

I've decided friends are the people who know you have pressure systems in your basement, and come visit you anyway. :)

You can see the big puddle of light on the wall where the glass focuses the flame.

caladri is starting off a four-foot length of lab glass tubing to make a shotglass. She heats it up and pulls it apart slowly, strething it into points. The tricky thing here is to keep the glass moving at all times - molten glass is a lot like honey and will flow towards the ground. There's a lot of motion in this - one dances with the glass as much as works it.

The next step it to attach a piece of glass ("punty") to the point you just pulled, so that you can handle and work with the shorter piece of glass without burning your hands.

Light and glass - you could always see the skeleton of the glass form, written in light on the wall. We joked about forging lightsabers.

*makes lightsaber noises* Pzzzt! Beeeeeyng!

(The white roll of bookbinding tape was used to try and attach safety goggles overtop regular glasses. When that didn't work, boojum of the crocheted hedgehog codpieces knitted a bridle to hold them in place. As I am a merciful sort, you won't get pictures of anyone's head with a yarn harness holding dorky purple glasses on.)

Okay, so I always wanted to be a Jedi. My parents wouldn't buy me a death star! It was awful.

SO here's gfish.

Once the shotglass has a handle, it's a lot easier to use a graphite tool to open and shape one end. This is robogock.

Here is boojum putting little glass spine on what may well be the world's first delicate cobal-blue viking shotglass. :) Mine has feet and a tail, and a melted, lumpy top. caladri's is about a foot tall. gfish's has a handle like a miniature beer stein.

The designs probably say something about our personality, but I have no idea what. Seeing in a glass darkly, indeed.

One of the saner finished models. :) robogock's. The only regret of the party is that we burned through an entire tank of oxygen, and not a glass for everyone who wanted one.


This is our smelting furnace. (Previous attempt here.)

It's made of firebrick, held together with clay and kiln mortar. Which is all well and good, but you have to understand that 2300-degree firebrick ceramic has a texture like cotton candy, styrafoam peanuts, and someone attacking a chalkboard with flaming automobile wreckage. The stuff makes bone-scraping sounds, crumbles, and stays hot for hours after burn-in.

This is the furnace in use. It burns charcoal, which is pure carbon, with the idea that all oxygen in the furnace will bind to carbon as carbon dioxide, with enough extra carbon to suck all the oxygen off the copper oxides in the ore, too, leaving pure carbon. This is called a "reducing" atmosphere - it reduces carbon oxides to pure elemental carbon. This is especially useful where there's a "bellows" (we don't hate our guests that much, so we used a vacuum) pumping air (with more oxygen we need to keep away from the copper) into the furnace to make the charcoal burn hotter.

In theory, anyway. In practice, the copper ore mysteriously got lost in the mail, so we were just melting some copper pipes we got at Boeing Surplus, as a test run.

But it's still white hot.

White hot might've be a bit too hot, in retrospect. At some point, the 2300 degree firebrick of the roof began to slag. The roof cracked and fell in. (this shot is from the balcony above the furnace. You could feel the furnace heat fifteen feet up and fifteen over, in the living room.

The lid fallen in.

The furnace eats the firebrick. Hooray for the triumph of the primitive over space-age ceramics!

And the next morning - copper in twisted bubbly shapes, like coral, and the firebrick reduced to green glass. Next up: trying with actual ore. We know it gets hot enough, but can we get the chemistry right?

The House:

The view from the deck. To the left of the space needle, down near the ground, you can see the Experience Music Project, my nemesis. It remains stubbornly non-ferrous, however. Grr.

This is the fireplace. This is what happens when you throw a glass of camping stove fuel on the fireplace. Naphtha burns as a liquid, but flares into an enormous fireball as a gas, so you have time to back away from the fireplace while it heats itself up. Then you end up with blue fire pouring over the floor and caught in the carvings on the screen, flower forms outlined in shining blue.

House: warmed.

If you wanted to make a shotglass and didn't because the oxygen tank ran out, consider this your free shotglass coupon. Email us and schedule a time to come do it. :)



Fwoom! Hooray for housewarming! We pulled it off! :)


Would you like to come over and work on glass sometime?

Also, are you still in Boston? I didn't do your introduction while I was at conference, but if you're still there, I'll do it now.

Yeah, that'd be fun. We (sadly) don't have any real torches at the lab now. I've got my welding kit, but the fire department wanted $216 a year for a hot shop permit to let us keep tanks around, so they went back to PraxAir.

I am still in Boston, but I work all day tomorrow and fly out in the afternoon. I'll be back out here again in a few weeks, so maybe next time, depending on how long I'm out here for.

That is an incredibly fantastic view. I'm so jealous. :)

Bricky things!

Are you using magnesium oxide firebricks, the ones you can score and notch with, well, your fingers? That's what I've built most of my stuff with, and it's great, but my ex-gf's glass kiln, gloryhole, and crucible furnace are all done using something that's nearly as hard as conventional bricks, and stands up to tremendous abuse. I'd like to find those and start working with them: rebuild the annealing kiln around them, for instance. (I'm sure they're much harder to work with, but I bet a tile saw would do it.) They stand up to white heat, too, apparently.

Have you looked into oxygen concentrators? A largeish one might be able to drive your torch -- is that a Bethlehem? -- and for a purchase price of about $200, it pays itself back reasonably quickly, depending on how much your torch is running. (When I'm cranking out beads, I'm going through a tank a week, at $20/fill. Oxy concentrators are supposed to be good for 20,000 hours or so after a rebuild.)

I want to try some nasty games with naptha. That looks like fun. Aerial dispersal should be worth exploring.

We were using the stuff that comes apart at finger tip. We've considered an oxygen concentrator but were concerned about our startup costs. We'll probably get one in the not-too-distant future, but spent way too much in way too short a time as it was :) We're also not going through it at a very high clip, yet. We started doing some glassblowing before the tank ran out, though, and I suspect if we get further into that at all we'll need a concentrator :)

I know some people that (somehow) use both a tank and a concentrator: the concentrator handles small/mid flame and the tank fills in when you really need a bundle of flame. My torch is definitely a two-concentrator machine, with a nozzle 20mm in diameter, but I think I could recoup the investment pretty quickly.

We need more research on firebricks.

Cor--wow, things have come a long way since the last time I visited you guys up in Shoreline with my camera. You've got a new place, some new heat toys, and a rockin' camera work.

I'd love to see it sometime, if that'd be possible?1

Of course! I'm in Baltimore right now, but you can certainly come by and play with glass/enjoy the view after this week.

I'm headed to Costa Rica until 12th starting tomorrow night, so I'll have to catch up with you in a couple weeks. =)



I'm so envious. That looks like it was an absolutely beautiful little party, exactly the kind of thing I'd hope to attend.

We use heavy reduction in our pottery kiln all the time; it's the only way to get some of the metals in the glazes into the right oxidation states for the colors you wan. The best example is a beautiful deep crimson called "copper red" being one of them, which requires copper(I) not the more common copper(II). The only way to get copper into that oxidation state is in a reducing atmosphere, which is a tricky thing in a big kiln at 2300 degrees.

When describing it to people, I usually use the phrase "monatomic carbon fog" to describe what's going on inside the kiln.

I wonder if your firebrick didn't crack because of a temperature gradient. We had cracking in our big kiln, despite the firebrick being wrapped in a silica blanket, and finally fixed it all by spraying a very thick coat of a refractory cement on the entire inside of the kiln. That worked... and the kiln heats much more efficiently now, too.

Eeeeee crafts plus science!!!!!

Whoops, that was me. How did I get logged off LJ? Stupid computers.

(I replied to your anonymous comment, by the way, which I guess you won't get notification for.)

I didn't know copper(I) was also useful for coloring things, nor that it was scarlet. I'm used to the blue green. (I also really like the phrase 'monatomic carbon fog'.) Keen! How do you get the reducing atmosphere in the kiln? I thought most of them were electric?

The glass torch can also be set to reducing or oxidizing flames by tinkering with the oxygen/propane balance - several of the dyes used in glass color only turn the right color under one atmosphere or the other. There's one family that's green one way and red the other - I wonder now if it's copper based, given what you just said? Would make sense.

I found some good examples of copper red (also called oxblood) here: http://www.onetreehillpottery.com.au/Red%20pots.htm

Yes, the usual ("easy") oxidation state of copper is Cu(II), which produces that greenish color like the Statue of Liberty. As a glaze colorant, it turns out a milky, uniform, almost opalescent green, which I suppose is pretty if that's what you're going for; I personally don't find it too attractive.

It's extremely difficult to get a reducing atmosphere in an electric kiln. It can be done by adding mothballs to the kiln load when you want to reduce. Mothballs are mostly naphthalene which is (by weight) 93% carbon and thus a good source of atomic carbon in the kiln atmosphere. The problem with this is that all sorts of corrosive compounds are also produced, which eat at the heater coils in the kiln and reduce their life. And the kiln exhaust is pretty noxious and probably carcinogenic as well. I've never even tried to reduce in an electric kiln, which is why I hate them so much; the chemistry of oxidation firings is kind of boring, as are (to my eye at least) the results.

We have a gas kiln with two pretty big propane burners with electric blowers injecting into the back. To get a reducing atmosphere, we turn off the blowers and stop down the air intake to something pretty minimal. The chimney is venting 2300 degree air at that point which creates a pretty good suction, so basically the kiln is sucking in nearly pure propane which at those temperatures rips apart pretty readily into that monatomic carbon fog. A little air gets sucked in, too, which supports combustion to keep the temperature from falling very much, although the kiln temperature will definitely stall out during reduction.

I've never gotten consistent copper red effects; we just don't have enough experience with our kiln to get a uniform strong reduction atmosphere. The best we've seen is smears and washes of red where the local atmosphere happened to be exactly what's needed to produce the Cu(I) oxidation state. Which, you know, can look pretty cool too.

It may be obvious given what YOU were trying to do at your party, but if the reduction phase of the firing lasts too long or the atmosphere is too strongly reducing, you again miss out on copper red because the copper atoms in the glaze get reduced all the way to the neutral metal, which for some reason when suspended in the rest of the glaze makeup usually winds up essentially transparent, so you've blown it again.

Keen! Thanks for the education. I knew copper had an (I) state, but not that it was so lovely.

You should throw a party where everyone gets to make and fire pottery. I know I would try to come. :)

Wow... that's just beautiful.


We missed you! :)

I'm sending you email, but I'm not sure what address is best. (A lot of things I don't have saved on the uw account...)

And, uh, I didn't make a shotglass, uh, because the O2 tank ran out, so can, I? Please?

Certainly! When would you like to?

Hey, thewronghands said you would be good to talk to about machine vision for robots and such. Come see me over @ my LJ when you get a chance. Thanks.

The thing about glass is that it all looks about the same when honey-molten. So you can't tell exactly where a particular piece or color is when you go to add more. It might be here, it might be there, so you have these two possible beads, ghost beads, you're making, and then you add the next color, and maybe it's here on top of this one, or over there, or right here... and now you have six ghost beads - you won't know which you made until it's cool, and every motion, every heat, every color just adds more, some teaming crowd of possibility in scarlet and silver foil.

I like this description!

I think I may have ended up with a bead made at this party (or another like it?), which I unfortunately foolishly lost soon afterwards.

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