Reduced Pottery Is Not What You Think It Is
HTML-код
- Опубликовано: 21 май 2024
- In which I explain what reduction is and more importantly, what it isn't.
Learn how to fire pottery with this masterclass - ancientpottery.how/courses/op...
🏺 Wednesday Zoom pottery class - ancientpottery.how/ancient-po...
❤️ Channel membership - / ancientpottery
OR Patreon - / ancientpottery
🛍 Shop my website: ancientpottery.how/shop/
📚 Workshops and masterclasses - ancientpottery.how/classes/
⭐️ Social media
Facebook - / andywardpottery
Instagram - / ancientpottery
📬 Send me mail
Andy Ward PO Box 43601 Tucson, AZ 85733
As an Amazon Associate I earn from qualifying purchases. 
Хобби
Dang now I want to smudge something. Andy your videos are some of the best instructives on the internet
Thanks Angela, better get out there and smudge before fire restrictions.
I wasn't clear on the distinction between smudging and reduction until now. That was a superb explanation!
Glad to help.
Wow, Andy! That smudged bowl is gorgeous!
Thanks. Smudging makes for stunning pottery to be sure.
I like that pueblo blackware, I've never seen it before.
Glad to show you something new
Great video! I enjoyed the clear explanations on what 'smudged' and 'reduced' mean. I hope it helps clarify things for everyone. Thanks for sharing Andy!
Thanks Will. It drives me crazy when people use "reduced" to describe smudged pottery LOL.
I'll be digging clay today. Thanks for the inspiration!
You're welcome, have fun
Appreciate the clear research. That all-black mirror pottery is strikingly gorgeous.
Thanks to you…I have successfully dug and processed clay on my own land and have almost figured out the firing. Still working on it. I keep breaking my purchased clay but my processed clay seems to be invincible, however a bit under fired, I think 🤔
Fire hot. Also be sure to add lots of temper to your commercial clay so it can survive.
Howdy Andy ! Lots to learn! thanks for sharing your wealth of pottery wisdom !
Hi Cliff, thanks.
Wish I could like this more than once! Guess I'll just have to watch it multiple times to make up for it 👍
LOL, thanks for that.
Very useful video. Thank you. Do you have a video that names all of the typical color schemes and where they are from? I love your history videos. Plz make more
No I don't, I will have to give that a think.
Thank you for another wonderful video!!
You are welcome
you are aking the absolutelely most devine videos. Thank you so much!
Keep sharing and responding please.
I’m glad you are enjoying them.
This was very informative, thank you Andy! I am trying to make a recreation of La Chamba cookware from Colombia and the finish is similar. They use a burnishing stone until the pot squeaks and then smother it after the firing os complete for that deep color
Yes, smudging is used all over the Americas. The black pottery from Oaxaca is smudged too.
Thanks Andy, for the clarification. It is amazing that Native Americans figured out so many different ways of firing.
Truly
Thank you. Thx for doing this, filming it and sharing it with us.
You are so welcome
I want to really thank you for what you do, finding your channel has changed my life, I always wanted to get into pottery as a hobby but I thought it would be expensive to get into, when I learned that you can do all this with no money, it changed a lot for me, not only with this, but it also made me realise that there’s a primitive way to do most things and things I used to think weren’t accessible to me are very easy now and it’s almost always free! I’ve now learned that you can make soap at home with ash, water, and rendered fat! I learned how to make ink and wooden dip pens just for fun, I know how to make paper too even if I might never actually try it, and everytime I find something new I might want to get into, I always learn the primitive way first, that’s because of you.
(Also during this I found this out, did you know that you can make electricity free air conditioning and fridges for dry climates with just clay? If you can make the shelves and the door, you can make a reservoir at the top for water, and the water will seep into the clay and evaporate in the air creating a cooling effect, same with the air cooler, you can make a bunch of tubes with something to seep water onto it and air flows through and becomes cool! I’m thinking about trying it, I think it would be a cool experiment for your channel too)
Thank you, I am glad you have enjoyed my content. I need to look into the cooler.
@@AncientPottery they tend to work best in dry climates because that’s when the evaporative effect works the best, if it’s humid not so much, there’s actually a company called mitticool who sells mini clay fridges, business insider made a video on them if you want to check it out
Excellent video. Explains the process well and really interesting too.
Awesome video!
Glad you enjoyed it
Just edited one of my Instagram posts ..you are correct as usual ..perfect explanation of the difference
Thanks Andy
you are welcome.
I 🖤 your videos! Your knowledge is extensive. I'm very grateful for your posts. Thank you.
ur awsome andy!! explaining it so simple and easy its impossible to not get it!!
I actually have a bit to add for once. I reduce all my work because it's American Raku. I don't think it's proper to call smudge ware reduced, I mean sure it's in a reduced oxygen environment but reduction refers to the metal oxides being reduced from an oxide to its metallic form. You are literally reducing the number of atoms in the molecule and then trapping it in that state in the glass matrix. It can also refer to the clay body itself taking on different properties but the mechanism of change is the same. Well that's my opinion at least. Good topic 😁
We should remember what oxidation-reduction is. It's a pair of reactions: one element is reduced and another element is oxidized. In other words, they exchange electrons. One receives the electrons; the other gives up the electrons. Technically calling it oxidation is a bit mis-leading. But because oxygen is often involved, people called it oxidation. Then the scientists learned that it's really all about electrons moving around, due to several chemical phenomena. In Raku, the number of atoms stays the same. We can't destroy matter. It's the electrons that go from one atom to another. When the number of electrons changes, we get color changes. Hence, when copper gains electrons, it goes from a positively charged atom (ion) to a neutral atom, elemental copper metal. That's why raku has those great metallic, iridescent, shimmering colors. And it's not just copper. Other metallic elements get involved. As copper gains electrons, other things (like carbon and oxygen) lose electrons. And by the way it's the heat that supplies the energy to make the electrons move around from one atom to another. And you have to have the right pair of different elements. Sorry to nerd out, but it's all basic chemistry. I learned this in college, but the AP kids now learn it in high school!
Excellent, informative, video.
Glad you liked it. Thanks
Very cool! Thanks Andy 😊
Another great video. Love the information you share with us.
Good as always
Thanks
You can smell the reduction! I did it by accident in my first pit fire. I was sniffing around going “oh my god…it’s reducing!” 😅
Huh, neat! I take my ocarinas out of an electric kiln and lower them into a metal trash can filled with organic matter. They burst into flame, I slam down the metal lid and leave them in there till they’re cool. My teachers called it smoke firing. I was told the clay changes color because of oxygen reduction, but this explains why I sometimes get shiny black and sometimes gray or brown depending on the amount and type of leaves or wood I use. Turns out I’ve been smudging more than reducing? I think? I need to rewatch and experiment more to be sure. Thank you for the info! Your videos are always so interesting.
I'm going to do another color test on my clays in a reduced atmosphere. That will hopefully help me figure out if I've got a yellow for Mimbres polychrome.
That's a tough one, let me know how it goes.
Excellent
Dear, sweet, selfless Andy,
I haven’t met you, but I love you to pieces. You almost always explain everything so well to us. For reduction vs smudging, I think you are making a distinction that is not necessary. I think it can be mis-leading to those who haven’t studied (and remembered) their chemistry. Or never had to take a class in the first place.
.
To put it simply, "smudging" is one of the many, many oxidation-reduction reactions. Although people first described incomplete combustion as reduction, that definition is a bit confining now that we know more chemistry. Eons ago, when there wasn’t “enough” oxygen in the atmosphere in a fire, we said the amount of oxygen was reduced. Conversely, if there was plenty of oxygen around, we said things were oxidized. Yes, most of the average person’s experience with oxidation and reduction involves oxygen. After all it’s a fairly common element floating in and around our earth and its oceans. But focusing only on oxygen misses the point.
Without getting too much into the weeds, what is actually happening is an exchange of electrons. Different elements can be involved. The element doesn’t always have to be oxygen. The carbon black we see in what is called “smudging” is an exchange of electrons. When oxygen is lacking, the carbon in the fuel converts to a “less oxidized form”, CO (carbon monoxide) or pure carbon (elemental, neutral C). The carbon atom gained electrons. If it goes all the way to elemental C, we get black particles, which deposit and are embedded in the clay pores. At the same time, another element loses electrons. There are other reactions also involving electrons being traded (like baseball players), given the right conditions. I fear boring everyone to tears if I go into too much detail.
As you correctly pointed out in the first 30 seconds of the video, this is what happens to the iron (Fe). In a “normal” oxygen-rich firing situation, the red iron oxide, Fe2O3, stays bright red (like rust, which is what it is). There’s plenty of oxygen in the air to burn the fuel. But, if we smother the fire and limit the available oxygen (in the form of O2), the stuff that’s burning (charcoal, wood, coal, sheep dung, whatever), is NOT happy. We were taught that the fuel wants/needs oxygen (as O2), to burn. So it goes looking around for O2. The easiest (and most common) compound to “steal the oxygen” from is red iron oxide Fe2O3 in the pottery. But here’s where we were mis-led. The fuel isn’t really stealing the oxygen. It’s stealing the electrons. They just happen to be attached to the oxygen in the red iron oxide, Fe2O3. The red clay or the red iron paint can supply the electrons, because they both have lots of Fe2O3. The iron changes its charge (gains electrons), as does the oxygen (but it loses electrons) in the Fe2O3. So, the iron gets some electrons. It becomes FeO, which is (…wait for it…) black. The oxygen breaks away from the iron and the fuel gets the oxygen and can then burn. Unfortunately, in a smothered fire, the fuel doesn’t get as much oxygen as it wants/needs. So things smolder and we get incomplete combustion. We produce CO (carbon monoxide) and elemental carbon (pure C), not carbon dioxide (CO2). So the fuel is (at least) somewhat happy, burns and the iron turns black. I've simplified what's happening to the oxygen, but trust me.
In sum, Andy, I think you separating a general chemical phenomenon into two events, which is unnecessary, and possible confusing. There are hundreds of oxidation-reduction pairs of reactions. Two elements are always involved. In the case of red Fe2O3, it’s Fe (iron) and O (oxygen). In the case of producing soot, like with “smudging”, we are talking C and O. Many potters know about producing amazing Copper Red glazes in the gas-fired or wood-fired reduction kiln. In this case, it’s copper and tin that exchange the electrons. In the case of the Statue of Liberty (turning bright copper to verdigris), it’s copper and oxygen.
For Maria Martinez’s Black on Black pottery, we are getting mostly iron reduction and oxygen oxidation, which produces black FeO. After all, it’s fired twice. First, it stays red (Fe2O2), because it’s fired in abundant oxygen. Then it’s fired again, in an oxygen-poor atmosphere. We go from red (Fe2O2) to black (FeO). And as an added benefit, the oxygen starved fuel doesn’t burn completely, so it makes elemental carbon, C, which is famously black, like coal is. So her pottery is really, really, really black.
I apologize if I’ve confused anyone. Happy Replicating!
@@lizmikols2075 you wrote a book to say you disagree with my analysis. I disagree with you as well, black ware pottery is, in most cases, indeed oxidized but that is covered up with carbon. I got some push back from Erik Fender in the comments here as well, he is an experienced San Ildefonso potter. So with all due respect to you and Mr Fender it’s all a matter of opinion until someone comes up with an experiment to prove the case. I am open to working with either or both of you to see this proved true be way or the other.
It's hard to explain chemistry is a few sentences. The experiments have been done, many places in many laboratories. Redox Chemistry is fairly well established. I still love you to pieces. XXXXX@@AncientPottery
Andy, thank you for posting this. My personal background was in sculpture but have been employed the last couple of decades as a high school ceramics teacher up in Phoenix and I always try to incorporate lessons in traditional firing methods into our curriculum. When showing videos to my classes I have noticed this problem of mis-representing (or confusing) the term "reduction" with "smudging" or "smoking" pots to achieve blackware. Some people do distinguish between typical high temperature reduction in a kiln and "post-firing reduction" such as used in "naked raku" and similar techniques. But is this truly "reduction" or just mis-applying a term borrowed from typical studio kiln-firing methods based on Asian and European traditions? Thanks again for shedding some light on this question.
Thanks. I wonder too if that "post-firing reduction" is really reduction. It also seems more like a smudge but I have zero experience with this.
I made a mill from a red wreath trees logs that people cut down in a nearby nature reserve. I did an experiment to see which temper works the best. I used charcoal, sand, grog, and sawdust. Sawdust made it lose a bit of plasticity but the rest did not really have much effect. With the sand 2 out of 5 cracked, with grog 1 out of 5 cracked, with crushed charcoal none cracked and with sawdust none cracked. I switched my temper usage from sand to charcoal because of the results and it doesnt really make it porous surprisingly
Well it doesn't make it porous, but hey if it works for you do it.
have you tryed "black on black" , can't wait to see how you'd do it.
I think entirely reduced ceramics can be achieved only in a kiln, so even the section of the sherds will be dark, like in many Roman dark wares. Otherwise, the reduction is mostly achieved on the exterior, from when the fire is covered up, but the inside of the section remains somewhat oxydised. I guess "reduced" in the case of south-western pottery is only on the exterior if no kilns were used and the section would present a succession of colours. For Martinez I would say they are both smudged and "reduced", as the combination of the two gives the most shiny result.
Black pottery the way Maria Martinez made them. WAS reduced iron, the red iron rich slip she put on them and the smothering of carbon monoxide rich carbon from manure caused some carbon capture along with iron reduction. Just my opinion.
If that were so then the areas coved with foil would be grey from the lack of oxygen. The smothering portion of those fires were not hot enough to reduce any iron.
@@AncientPottery in my experiments direct reduction CAN occur around 1300f of just iron rich clay. There is always an argument about this in the pottery world when it comes to iron carbon capture and carbon coring . I am not trying to argue my point. But knowing the secret to success is in the clay chemistry. And preparation. San ildefanso clay has the right chemistry for red clay slip to reduce at low temp, Direct reduction , smothering with carbon gasses is only part of it
I believe that tewa blackware is fired at a much hotter temperature than what has been stated in books, videos and such. I like to fire at night to be able to see the glow better and my pots are glowing red at maximum temperature. So a combination of reduction atmosphere and carbon capture.
@@erikfender8940 I have a thermocouple and an infrared thermometer so would love to come measure one of your firings.
@@erikfender8940 wow ! Thank you. I know there are many ways to look at it. I too try to fire in the evening when I can see the right glow. The true masters of reduction firing still exist among many indigenous peoples, it’s obvious in modern contemporary indigenous pottery to me. Thanks for your input, thanks very much 🙂
Andy, I'm wondering if you have ever tried or considered using an oily plant resin in a solvent like ISO alcohol, as an organic paint? And how long is too long to wait between applying the white slip, and painting onto it? I have a pot I made a few months ago that is bone dry that I never got around to painting, and I have this organic resin that I could dissolve in alcohol for a paint. Theoretically it should work
I didn't know about Andy when I first experimented with firing pots. Some of my first little ones came out entirely black, and rather pretty that way. I'm still not completely sure whether they were actually reduced or smudged. I fired them underground covered with organic material and dirt with a fire built on top. That fire burned down to coals, and the following morning I dug out black pottery. So you tell me. Was it reduced, or smudged? I still have a couple of the pieces. I use them as little pots for various slips and stuff.
Smudged, unless you smothered it with earth.
Thanks, Andy! Loved this video. Some Maria Martinez black ware was/is housed at our Santa Rosa (CA) junior college. Mind-blowingly beautiful.❤
i've been smudging thinking i'm reducing.
I would like to know how potters get a mirror-like polish that lasts through the firing. Does this require particularly ultrafine slip, like terra sigillata? I can burnish to a mirror shine, but what comes out of the firing looks quite plain. Anyone have any advice?
I have watched several of your videos of the wild clay, here in Dallas, Texas it's really hard to find, i was wondering if you could send me some?😊
Ha ha. I used to live in south central Oklahoma just north of you. That area is crazy with clay. Take a little road trip.
Hi Andy
Is your red denim'ish shirt dyed with cochineal?o
Is that the only way to make blackware? I thought the people down in Mata Ortiz were doing it differently.
No, they smudge too. They do a couple of extra steps though, they slip with manganese (insurance against a poor smudge), and they slip with graphite (provides the metallic shine). But they fire smothered under a bucket with horse manure which is just good old fashioned smudge.
@@AncientPottery Thank you
👍
Is your white slip made with caliche
No, I have several different white slips but they are all clay, no caliche.
I have to somewhat disagree with you about tewa blackware not being reduced. Although it has a lot to do with the carbon produced by the pulverized horse manure it also requires a reduction atmosphere while being smudged . We trap all smoke and do not allow air to enter the into the mound after we cover with the manure. If smoke escapes and air enters the mound the pots won't be jet black and start to turn red again. There is a lot more to getting our pots the black we strive for. Also your description of how black pots have two tones is also slightly oversimplified and I don't know anybody that uses foil to produced the variations. Also that brownish Maria pot was first fired totally black then refired in a oxidation atmosphere to burn out the carbon, so it started off burnished red with white slip designs painted on then fired black on black then refired to produce what we call a sienna color. Don't get me wrong, I appreciate what you do but sometimes your descriptions and info are a bit off.
Well I defer to you Erik. I had read that foil as used to create that, was it used in the past or was that just wrong information? Would love to learn more about how it is produced and I am always available for a visit and long conversation if you are interested.
I think we could design an experiment to see if Tewa Blackware is reduced or not. It could be very interesting.
I'd be more than happy to talk to you more about the firing process for Tewa blackware and you can't always believe what you read or hear. Aluminum foil would either melt of completely burn off in one of my firings. I know this because I had found a sheet of metal that I thought would be good to cover the pots in a firing like a cover sherd but it ended up starting to melt about five minutes into my firing. It was much thicker than aluminum foil and I wasn't even up to maximum temperature yet. Like I said I'd be more than happy to talk pottery with you at some point, but I know we are both always busy and it will take some scheduling at some point.
I appreciate that you are busy and am willing to as flexible as possible to meet your schedule. If you want or have time shoot me an email from my contact form and then maybe we can make this happen. ancientpottery.how/contact-us/
Eric- you are clearly very knowledgeable in this area so I'd appreciate your input. I had heard that the color variations with blackware fading in select areas to reveal the natural red-brown color of the clay were achieved in modern work by using a hand-held propane torch to carefully burn away the black carbon finish. I have tried this method a few times on some sherds with success, but never on a full size pot for fear of cracking the piece. Are you familiar with this technique?