/diy/ - Do It Yourself

>>1464349
Potter here. You're not the same Aussie from the other thread asking about classes in Brisbane, are you? If so, you need to take a class or find some text books.

Yes, it should be relatively safe, although it would disintegrate in about 10 minutes. The main safety hazard of unfired clay is inhalation of the dust, causing silicosis. You must fire a terra cotta clay to at least a bisque temperature (at least 900ºC) in order for it to be permanent. Terra cotta clay will always be porous like a flower pot until it is glazed. Unglazed, fired terra cotta will hold water for a time, though it will slowly seep through the walls. Cool you got a wheel though. I'd like to see photos. I repair old ones. Start looking for a kiln to buy or a place that offers kiln firing services. A wise move to make is to attach yourself to school/university or a local potter's guild or club to find opportunities to rent kiln space or buy used kilns.

>>1464367
not the same guy but thanks for the advice.

the one i have is:
https://www.ebay.com.au/itm/Electric-Pottery-Wheel-Machine-25CM-220V-250W-Ceramic-DIY-Work-Clay-Art-Craft/292671006127?hash=item44248d25af:g:DCIAAOSw-f5baTrO

i was hoping i could just make a kiln from some bricks and charcoal in the backyard...
any recommendations on glaze?

>>1464349
https://www.youtube.com/watch?v=Nsz8vPAEB0g

>>1464371
>i was hoping i could just make a kiln from some bricks and charcoal in the backyard...

https://www.youtube.com/watch?v=lMi1P-J-nmY

>>1464371
Huh. Looks like a knock off of the old Shimpo wheels. When you get it, look underneath and see if it's a v-belt drive or a cone drive. I've repaired some of those old Shimpo rk-2's with hilariously quaint cone drives.

Yeah, you can make a kiln. You could go with kanthal elements or use LPG burners. I would not recommend building a solid fuel kiln as your first one because you'll need to construct a chimney 2-3x the height of the firing chamber to get draft, as well as a firebox. That makes it a lot more complicated. With electric, or bottled LPG venturi burners, you can get away with a much smaller and simpler firing chamber made out of high-temp firebrick, insulating firebrick, or even ceramic wool fiber. You can make simple, efficient little catenary arch kilns with brick or a castable mortar, too. It's fun stuff. Start looking up kiln plans.

I don't know any earthenware glaze recipes off the top of my head, but I'm sure I have some somewhere. What is the specific firing temperature of your clay? It should be on the box somewhere represented by cone numbers. Pyrometric cone are what kiln crafts use to measure melt/maturity of clays and glazes. They are standardized cones or bars of ceramic materials that bend under specific heats, heat being the function of time + temperature.

>>1464377
This is cute, but you can see he maxed out the temp of the kiln at around 750ºC, which is still too low even for terra cotta. You have to use coiled kanthal elements. There's some nerdery involved with calculating what gauge wire, length of wire, and coil diameter involved there. What I do is call up a place that sells the wire and ask one of their staff nerds what to buy based on my application. If you want to DIY these calculations, you can find them in The Kiln Book, by Frederick Olsen.

>>1464388
um no. He set the temp at 750C to melt aluminum
It can go much higher than that.

Charcoal will get you 500C max

>>1464395
Open to interpretation, but he says "it's 786º and it's pretty much maxed out". I think maybe it could get a little hotter than that in a few more hours, but I highly doubt it would go beyond 1000ºC. Come on, dude. He used maybe 1.5" thick ifb's with standard oven nichrome elements. Charcoal will get you to white hot if your kiln design is good enough. Nichrome will not even get you to yellow heat.

>>1464412
Heating elements 2 x 5000 Watts / 240V
melts gold

>>1464424
1000ºC is the minimum temperature required for bisque-fired ceramic. You understand this only puts you in the bottom of the firing range for unglazed, relatively fragile terra cotta pots? That little test kiln right there has 2.5-3" thick ifb's and kanthal elements. Now that one will get you to at least 1200ºC, which would just slightly exceed OP's needs. Why are you talking about the melting temperature of gold in a ceramics thread?

>>1464429
>Kanthal® salesman

>>1464435
It's just the standard alloy used in ceramic kiln elements because it's relatively cheap and slightly surpasses nichrome. I didn't make the world the way it is. If I was shilling, I'd say the guy should buy silicon carbide elements or something ridiculous. I think the easiest thing is to just acquire a shitty old used kiln anyway. If it's in decent shape, just rewire/patch it. If it's a piece of shit, just use the brick shell as a blank hotbox to build an internal chimney downdraft kiln with a cheap LP weed burner. There's a Simon Leach video or two about that.

>>1464388
>You have to use coiled kanthal elements. There's some nerdery involved with calculating what gauge wire, length of wire, and coil diameter involved there. What I do is call up a place that sells the wire and ask one of their staff nerds what to buy based on my application. If you want to DIY these calculations, you can find them in The Kiln Book, by Frederick Olsen.
What's the point of Kanthal over say Tungsten? Is it just that the positive temperature coefficient allows you to use early 20th century control circuitry?

Clay converts to pottery at about 1,000 F. The water that evaporates as clay dries is simply physical water. However, at about 1,000 F, the chemical water is removed. This produces a molecular change--making the clay into a stone-like substance that no nolonger softens in water.

https://www.goshen.edu/art/DeptPgs/rework.html

>>1464442
Clay only fired to 1000F is also extremely friable. It may have lost its ability to become plastic when its chemical water is gone, but the cristobalite lattice will not have sufficiently formed to have much functional use. Little crunchy flakes will come off and end up in your mouth. Or in your glaze bucket.

I had a dumbfuck at my studio once who dipped some extremely low-fired bisque ware in my glazes. Story was the kiln he used shit itself round about 1000F, but fuck it, right? Technically, it's ceramic now! Fucking tiny flakes of half-baked pot in all the glazes. I got to re-sieve all of them later. Good times.

>>1464441
Kanthal is the trademark for a family of iron-chromium-aluminium alloys FeCrAl

>>1464454
>Story was the kiln he used shit itself round about 1000F
Kanthal® tends to do that.

>>1464441
Tungsten oxidises heavily above a temperature of 700°C. You won´t get more than an about a dozen hours of lifetime out of a tungsten heating element in air (or any atmosphere containing enough oxygen). Tantalum and niobium would probably work. Aside from that, heating elements with silicon (SiC, MoSi2) are often used for the highest temperature in air. Some of the furnaces at my university had MoSi2 heating elements. Kanthal and similar stuff should be good enough for 750°C, maybe even some CrNi alloys would suffice.

far better than nichrome, doesn't oxidize like kanthal

>>1464464
>You won´t get more than an about a dozen hours of lifetime out of a tungsten heating element in air

Yeah, I have to buy a new stovetop twice a day - not.

>>1464464
For 750 degrees a broiler element works fine, they run substantially hotter than that in an oven.

>>1464470
>I have a stovetop with tungsten wires that are exposed to air.
No, you don´t. At best, you have insulated tungsten wires inside a tube made of some cr-containing steel.

https://www.dw-inductionheating.com/Technology/Induction-Annealing-Tungsten-Rods-135.html

>>1464477
>https://www.dw-inductionheating.com/Technology/Induction-Annealing-Tungsten-Rods-135.html
Read the pdf linked there:
"Tungsten and Molybdenum; Tests are run in an atmosphere of
Nitrogen or Hydrogen avoid oxidation of the materials."
It´s pretty simple: Tungsten and molybdenum (if not made of a fancy alloy containing a lot of other elements) cannot stand air at high temperature. Just accept it.

>>1464470
A hundred years ago an American company wanted to sell light to dummies who slept all day and missed out on sunlight. It was a brilliant marketing scheme. Being that most people couldn't blow glass, or magically create "vacuum" they convinced their prospective buyers that tungsten explodes if it comes in contact with air, so they wouldn't try it at home.
They told a tall tale of 199 explosions and many fires to scare people into buying their "electric candles".
People in New Jersey still to this day believe that Thomas Edison invented light bulbs.

>>1464480
>Just accept it.

>>1464492
Best grifter of all time. ripped off more people than Bernie Madoff. Con Edison, lol

>>1464464
This is a photo of my kiln at 2350ºF. I regularly fire it to that temperature. The relatively inexpensive Kanthal elements last approximately 2000 hours in oxidation. They are not prohibitively expensive like molybdenum/silicon elements. New ones are fired at a specific low temperature initially in order for a protective oxidation layer to form on them before they can be fired hotter. This layer will be dissolved in a low-oxygen atmosphere and they will very quickly break. Silicon elements are relatively immune to reducing atmospheres, but they are very expensive. Potters choose fuel-burning kilns over electric resistance kilns when they want to fire in low oxygen atmospheres because it is cheaper, and they can control both the temperature and the atmosphere via the efficiency of the combustion.

>>1464379
>Huh. Looks like a knock off of the old Shimpo wheels. When you get it, look underneath and see if it's a v-belt drive or a cone drive. I've repaired some of those old Shimpo rk-2's with hilariously quaint cone drives.
ill check that out tomorrow and post pics


>What is the specific firing temperature of your clay?
Ideal firing temperature 1050C-1100C
Fires 1000C pink (underfield or bisque), 1090C deep red, 1150C starting to go brown
Can also be left air dried.

>>1464462
>Kanthal® tends to do that
Yes, when you're so cheap or lazy that after 200 or more 8 hour firings you haven't put aside $150 for a new set of elements and an hour of your time, it does do that sometimes.

>>1464541
I'll look for some glazes in your temperature range later. Keep an eye out for used kilns or places who will fire your work for you. It is very important that you are dead certain about the firing temp of both your clays and your glazes. People freak out about that because molten pottery can cause hundreds of damage to their kilns.

Really hope it's got a belt-drive. Those old cone drive ones had terrible torque. It's not something you can't deal with, but it'll be a pain in the ass to throw big shit on in the future.

>>1464550
it was only a couple hundred, if i ever get serious im definitely thinking of purchasing a more robust wheel.

im actually on gumtree looking at some used kilns...there's a few but they don't state how hot they go and they're a bit of a drive.

>>1464541
But meanwhile, here's a cone chart for you so you can start researching.

>>1464551
Hey, the Chinese wheel might be awesome. Who knows? That's why I'm curious about it.

>>1464551
>looking at some used kilns.
https://www.youtube.com/watch?v=vQTk2wXDx2U

>>1464551
Sadly, a lot of used electric kilns are sold by the relatives of dilettantes or dead potters. They have no idea what they're selling. If you're lucky they took a photo of the sticker on the control box so you can look up the model number. If you find something that looks decent I can try to help you figure out if it's worth a trip for you.

>>1464567
https://www.gumtree.com.au/s-ad/maroota/miscellaneous-goods/ward-15-amp-electric-kiln/1191083927

https://www.gumtree.com.au/s-ad/lalor-park/art/electric-kiln/1182816010

these two within my price range and
>>1464564
i'd love to do that but i dont think i have the yard space. i live close to the city but we do have tonnes of clay in the ground around here. not too sure what type it is though.

do you guys think its possible to smelt metal in a pottery kiln?

>>1464567
So there's a lot of sunk cost mentality with these things. People are thinking "I had to store this big piece of shit in my garage forever, so I deserve almost full retail for it!" When in reality, the vast majority of human beings on planet earth do not want and old kiln and would have to pay a couple hundred buck for some guys to take it away. If you look long enough, you'll find people who have come to reason and are practically giving them away. Do not balk at those, even it they're utter pieces of shit. Remember, those ifb's are worth $3-5 a piece and can feed a better kiln.

>>1464570
https://kriegerscience.wordpress.com/2010/08/04/how-to-smelt-metals-from-ores/

>>1464570
Depends on the temperature and if you needed to smelt in oxidation or reduction. But yes, they are generally useful for ceramics, metal, and glass.

>>1464567
>>1464571
anybody have experience with this brand?
https://www.firedartaustralia.com.au/kingpin88-with-bead-door

>>1464569
>https://www.gumtree.com.au/s-ad/maroota/miscellaneous-goods/ward-15-amp-electric-kiln/1191083927
Too small
>https://www.gumtree.com.au/s-ad/lalor-park/art/electric-kiln/1182816010
Decent size, decent brick, questionable elements (as usual, always be prepared to have to spend $200-300 AUS on new ones), potato controller photo (you have to call and investigate), fuck huge so you'll be renting a truck with a lift gate at least. See if you could talk the guy down to $500 with the rationale that it's going to cost you so much to move it, because it is. You only started looking today. Good, cheap, soon: pick two.

>>1464570
Just to clarify smelting is very different fro melting.

Heating up rocks enough that metals ooze out of the pores, generally takes a lot more heat, time, and energy, than simply melting.

melting point of most metals is nowhere near it's boiling point

>>1464580
No, but it's probably great. Way too expensive though. It's the size of a toaster oven. You could build a ghetto version of one that small pretty easily if you look for guides. I see those on craigslist here all the time. Unless you're doing some really fancy, but tiny work like enameling or something I can't see how something that small would be very useful.

>>1464544
excellent sales pitch, 0.4 cents have been deposited in your Kanthal shilling account

>>1464567
My local school board sells dozens of old broke kilns every year. people buy them and sell them on ebay.

better than fire brick

>>1464596
thanks for that ill look around more

>>1466298
You've gotta keep your eyes and ears open. Seriously, you need to join a local potter's guild or club. I assure you all the local potters everywhere in the world know each other within 1-2 degrees of separation and they hear about the good kiln deals faster than the internet does. I've found the best way to collect a list of the local guilds is to ask the guy who works at the ceramic supply retail store nearest you. They'll have an email list of almost everyone who buys materials.

>>1466307
oh yeh thanks for the pro tip, found a lot of robotics clubs and stuff but not a lot of pottery.