Black Reduced Iron Pottery Firing
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- เผยแพร่เมื่อ 8 มิ.ย. 2024
- Many ancient Southwestern potters used iron oxide to make black designs on pottery. This video shows my attempt to reduce iron on pottery to make black designs. Follow along as I paint my experimental pot with 9 kinds of iron paint then fire in an outdoor reduction fire. What will the result be? What can be learned for future reduction firings? Come along with me on this pottery adventure.
My first attempt, reduced iron ladle - • Making a Ceramic Ladle...
Collecting iron ochre - • Exploring Ancient Clif...
Learn more about Paul and Laurel Thornburg and their firing method - sarweb.org/wp-content/uploads...
0:00 Why reduce iron on pottery
3:32 Painting the bowl with 9 kinds of iron oxide paint
7:19 How to a fire reduction on the surface of the ground
15:19 A look at the results of this experiment
19:12 Ideas for future reduced iron pottery experiments
#reducedironpaint
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Andy, I'm following this trip you're on with huge interest. From a rather waterlogged farm in Cumbria, England! You are a special talent, in my very humble opinion.
Thank you SJ. I would love to visit England some time, my ancestral homeland.
One thing for sure is sand is highly porus. No way to get ruducing invironment with only an inch or less sand over it. For what its worth im a geologist. Clay rich dirt is what you need to block the oxygen. Sand works to spread the heat evenly around your pottery but not to block oxygen. A thin layer of dirt on top that sand probably would have gotten you the reducing environment. Im new to pottery but not new to rocks and soil. Thanks for all your intructions. Im just learning all this stuff. Im lucky to have a road cut next to my property so i got all colors at my disposal. Should be fun! Thx!
Thanks for the info.
Andy you know I have been working on this for some time! I’m closing in ! One thing I will say, a pot with fugitive red color refired again will get darker and darker but I’m not sure that was how they did , but some pots may have just been in the fire many times
Thanks for that tip Jeff. I am going to refire this soon so we will see.
I just made some bowls glazed with salt, hight temperature and also a iron oxid piece was inside of the kiln. The finished bowls were glazed in salt, ash and perfect black iron oxid...
Cool, I have no experience with glaze or kiln firing, so its always good to learn what people are doing.
Curiosity, experimenting, learning from failures...The stuff life is made of, maybe for. Michael
Definitely!
This is just what I've been experimenting with. Thanks for your (usual) perfect timing!
You are so welcome!
Still trying my paint not much luck yet been fun watching you the trying to get it to work great hobby
Thanks 👍
Somebody mentioned on one of the FB groups that iron oxide should be painted on very thinly to go black when firing. On newsprint, the lettering should still show through
I wonder why that would be? With the lead glaze I have been experimenting with it seems to favor thicker applications.
I believe that you had it with the ladle project. If you have a cover sherd that will completely cover the piece being reduced and bury it with dirt or very ashy sand, and bury it deeper than a couple of inches. That should produce the reduction were all aiming for. I'm working on a project right now, and I do believe were all learning. I'm sure that the masters of Anasazi were still learning at the point of mastery. I will share my reduction firing results as soon as I could get a burn permit. I'm slipping with a matte white texture instead of a shiny burnish, because I had luck getting the hematite/clay paint to become permanent on a bowl with no burnish. Haven't tried the reduction at all yet, but I am coming into it with a lot of great info thanks to your videos. Thank you Andy!
Thanks Mark, I look forward to hearing how your firing goes.
Of the objective was to get an intense black, then I guess the experiment was a mixed bag. But the bowl is beautiful and more interesting than plain black and white.
Thank you, I agree. I will be re-firing this bowl though to see how I can improve.
Loved the video! I’d really be interested in seeing where you got that ochre, also I would really like to see you do a video on some simple classic Basketmaker/other designs that were used on pottery and maybe other items.
Thanks. The ochre source is shown in this video th-cam.com/video/HHWkg9gELGk/w-d-xo.html
Very interesting to hear your explanations and see your results. Another good video.
Glad you enjoyed it
Reboot caught me off guard man.
LOL, I used to love that show long ago.
Great video and lots of good comments. The white slip was wonderful. It looked like you took your time covering the pot with sand. Would doing it more quickly make a difference? Looking forward to the next step.
That is possible. But, in my experience, pots sitting among hot coals will still not oxidize until those coals start burning out, so I would be surprised if it happened while the pot was sitting right on top of all those hot coals. Thanks Wes.
I like it !
Thanks
great video! i found this really helpful as ive been readying to do a similar reduced iron firing soon and have never tried it before. ive been studying a greek method however, and from my research 1 important thing for their 3 stage firing process was the flux used in the slip. the time period ive been looking at reproducing didnt create glazed pottery, but did achieve a partial vitrification of hematite slip by incorporating soda ash or potash similar to what would be done in a glaze. from what ive read that partial vitrification helped seal the black iron from oxygen, preventing it from reverting to hematite even when the pot was re-fired
That's helpful information, thanks. Any idea what temperatures they were reaching to vitrify that hematite slip?
I too have been working on this. With some success but inconsistent . I hope to narrow in soon and share with everyone my findings !
@@AncientPottery they suspect 1700 Fahrenheit with a kiln updraft setup
@@coopart1 hmm, I easily reached 1700 F in this firing. Perhaps I just didn’t hold it long enough.
@@AncientPottery could be Andy. I think we are all missing either a process or a known mineral throughout the southwest . I have hit the nail on the head and then next fire something goes different. I’m testing some new material from the silver city and mimbres river area this weekend so wish me luck !
Hi Andy, I haven't tried this myself, but a Danish potter once told me that the blackware that they made in Jutland in the 19th century was fired for a very long time, something like 16 hours if I remember correctly. (The goal was to make it look like iron cookware, which had become fashionable, but was more expensive.) So but the firing time could be a factor as well, maybe by getting the iron particles into a form that won't oxidize as easily?
This is interesting, I too have been spending a whole lot of time trying to solve this matter. One thing I have discovered is re firing a piece over and over does eventually lead to a dark blackish brown.
Thanks for that. I do wonder if time might be a factor, although I doubt it was anywhere near 16 hours in an open fire, that would use a truckload of wood.
Andy I saw a video a while back which has since been removed, patent issue perhaps. The guy levigated clay dried it out too make a superconductor (like a battery). The recipe went like 20% clay to 80% activated carbon. It was fired in a kiln from memory to 800C and it formed a hard black ceramic tile. I am wondering if you could powder some charcoal and add it to the iron oxide. It might be something worth experimenting with and charcoal would definitely fall into primitive material that were available. It could be tested on its own as well. Anyway you'd have a better idea if you go down that road.
that sounds interesting, too bad the video was removed, I would like to learn more about that.
@@AncientPottery I noticed this today and it was clay that had charcoal in it. The guy is a wheel potter but you can skip to 10 minutes and see before and after. th-cam.com/video/UQyZySvDhZ4/w-d-xo.html
Hi Andy! Great experiment! Sand is not the issue: I fired pots really black covered in sand on a beach. I think you covered the fire too late: the combustion is not agressive enough to take out oxygen from the pot (or its clay paint), to get it wholly reduced. I covered the fire when it was the strongest and kept covering up the small holes that appeared, took out the pots after one and a half hour, I could nearly touch them with my hand (didn't have a thermometer). Although I didn't have any white paint on my pots, so I don't know if that would come out good in my way. Balint
Thanks for the feedback. If you were making all black pots then your fire was more smudging that reducing. There is a difference check out this video th-cam.com/video/Lc7Fb2epkh8/w-d-xo.html
There are a few spots where they are slightly red coloured, I guess close to the chimneys and around the spalling on the small jug, from where it may have got more oxygen during the explosion perhaps from the pot itself. I don't want to break them as these are my first pots ever made! I'll be trying the same method with white clay without iron in it, just to check if this is smudging or reducing. I just have to finish painting the pot with red clay. In the sherds I study from Greek Macedonia the dark colour penetrates into the thickness of the walls, but not entirely, so that must be the effects of reducing. But there are no painted designs on those sherds to make a difference. In archaic and classical Greece they used reducing and oxydising to get black figures or backgrounds on red but then they were using kilns too with higher temperatures (and wheels), I wonder if that will turn out to be the issue.
I would love to try some colors. I have my red Iron-oxide now. I am still waiting for the white clay I ordered. (I am sure you have it in the mail.) Also, I am having trouble getting my pots ring like yours. I believe I am up to temp when firing. Would cracking in some parts keep the solid parts from ringing? Like you, I am still learning. Thanks for sharing your experiences. Finally, You just brushed on the white slip, right? No polishing?
I think you are confusing this with the Salado Polychrome pottery. Salado uses the special white slip I am selling on my website and organic paint, it is fired at a very low temperature. This is mineral paint that is fired at a very high temperature, if you use my clay at this temp the results may not be so good and organic paint will not work at these temps. The slip used in this video was brushed on and polished, the special white slip used on Salado Polychrome is brushed on and not polished. Sorry if I am confusing anyone, I am trying to understand several different types of prehistoric pottery and some of these types are made very differently.
I wonder if after you place the sand on, if you placed more of a damp mud on top if that would make it reduce better
Yeah, I think you are right, that sand was just too porous.
👍
Can you make a black ceramic paint with clay and charcoal or graphite and a little water? It dosen't burn off until about 750C? And internet thinks carcole burns off at 1100C, so maybe can move some nice blacks with those maybe?
What if you left the burning wood and coals in place and bury the whole thing with deeper sand or ashes from old fires? Also, leave the pot covered up overnight until it's completely cool so it doesn't re-oxidize? I'm no expert, but I've seen that kind of reduction work in simple pit fires.
Sorry, commented before watching the end of the video. Burying it with dirt or ash or something denser than sand would probably work better, and leaving it buried for a few hours or until the pot is cooler would probably work rather than overnight, unless you want to camp out. I don't know if burying it with the coals and burning wood in place would help keep the temp high for longer, but I assume it would.
Yep, my thoughts exactly. I'll be trying this again soon.
hi Andy..what was the white slip you used.? .Most of my clay is red so need a good covering .. good experiment
It is a white clay I collect here in Arizona. White clay is much more rare than red or brown but I'll bet you can find some where you live.
@@AncientPottery Thanks for the quick reply Andy.. I've got some of the Clay mine white.. Wes sent me a few samples over.. Got a small bowl to try reduced iron design on. 2/3 iron, 1/3 fine red clay.. Let's see!
Have you tried bone ash? Beautiful work!
Thank you. What would I use bone ash for? Pigment, temper, something else?
I have to ask... what is the name of the beautiful music in the background?
Sorry, I have no idea. This video was made so long ago, I can barely remember what I ate yesterday
Just a thought, what about putting the shards then dirt then fire it, allow complete cool down?
You would have trouble getting the heat to penetrate the dirt.
Does the pottery have to ring in order to know if it’s fired properly, mine won’t ring but it’s extremely hard and when I take my nail and scratch it the noise is very glassy
That's what I do, maybe not though. Try putting water in it, that is the ultimate test, if the pot falls apart when it gets wet then you didn't get hot enough.
What is the organic binder made of?
Mesquite sap
What kind of paint brush did the people you study use ?
Yucca leaf
I found a bucket of black iron oxide in my basement. Did I get lucky? Is it going to get brown too? What can I do with it?
Not sure. I have limited experience with commercial products and I'm not sure how you could have a black iron oxide because I thought that iron always oxidizes to red orange or yellow. Give it a try and see what it does.
@@AncientPottery it's a kind of magnetite ( yes it is slightly magnetic, I have been told) and it's occuring naturally and can be synthesized. It's when you heat up red iron oxide in an reduced atmosphere. So what you did. I was researching since I left that comment. Thank you for your videos, I learned a lot.
I have a question about fire clouds. I noticed if I reheat fired items up to some degree fire clouds would vanish. Have you ever tried using kitchen oven for removing fire clouds?
Interesting. No I haven't, I generally like fire clouds so wouldn't want them removed. What temperature?
Maybe smother it in clay instead of sand
Yes, I think you might be right, something much more impermeable than sand. Lesson learned.
@@AncientPottery These guys were using powdered horse manure
th-cam.com/video/Q7bYavfBhDY/w-d-xo.html
Hi Andy, we love your videos. We've learnt so much. Thank You. I was recently watching a Tony Soares video where He snuffed out the fire by putting a metal drum over the fire. @ 10:45 here
th-cam.com/video/ahqMJTSf_2o/w-d-xo.html
I know he's doing a different firing than you are and I figure that the ancient peoples probably didn't have metal drums but... Maybe if you had a really large clay vessel large enough to cover the fire. It could work well to replace the metal drum?
Although I can see that being a bit cumbersome to work with in hindsight
Yes, a metal tub would work well to smother the fire, but I am trying to figure out how it was done in prehistoric times. So I am sure they were using earth to cover the fire as it is the only thing they had that would have been able to cover all the potteries in a fire.