Glaze trials, Dragon tales, etc

It’s a rich time.  My last rebuild on my oil burners and fireboxes seems like it was successful.  I really hope I don’t have to do any more work on it, it’s been such a struggle.  Creative ideas are flowing, not always true for me. Some artists have a dozen ideas a day, I’m more of a one idea a month guy, but I’m back into exploring colored clay projects and loving it. I’m working on throwing patterned blocks of colored clay. The trick with these pieces is “how do you throw a pot on a spinning wheel without twisting the clay?”  Here’s a bowl, not glazed yet.I have a lot of excitement for this process.  I think there’s great potential for unique and beautiful pieces.  I’m also working on my next image block.
Puff, the Magic Dragon has been a kind of mascot for many years. The Puff sculpture on my homepage was born in my studio about 10 years ago. Puff has a lot of fans on Kauai, partially because of the song reference to “a land called Hona Lee” which many people take to mean Hanalei.  People drive around singing the song with their kids. The energy fits with Kauai.  It seems like the kind of place Puff would want to live.  I didn’t plan on making a dragon (life is what happens while you’re busy making other plans..) but the project I started was going dismally wrong and Obie (apprentice) & I ended up making a dragon. I set him up in the yard and stepped back for a good look after a month of work and recognized that it was Puff.  A customer asked for a tabletop version and I asked our friend Renee to do the clay while I handled the glazing and firing. She’s a really good sculptor, way better than me, to wit:

I’m drying the dragon reaallllllly slooooow to prevent cracks.  Meanwhile, my fascination with Flambe glazes continues.  I do lots of tests I have tested thousands of glazes in my life as a potter.  It’s tedious work and has to be accurate.   Here’s a mistake, it’s supposed to be red but has 10x too much silicon carbide in it:

This is called a “Crater glaze”.  Interesting but not what I want.  These are a few recent tests:

It takes 5-10 minutes each to make these depending on complexity.  Only about one in a hundred is useful, the rest are “educational”. I have 10 boxes like this and have thrown out about the same number:

This one is interesting.  These are exactly the same except the darker, uglier one has 1% tin, the lighter prettier on has 0.5% tin, a tiny percentage but the difference between a beautiful glaze and a failure:I wouldn’t have expected a small amount of tin to have such a big effect on color, it usually doesn’t have any effect on color at all.  It must be a chemical reaction that I don’t understand. Trying to figure out how to make beautiful glazes is totally frustrating 95% of the time and incredibly rewarding the other 5%.   The finished glaze is a result of the combined effect of chemistry, firing conditions and temperature, application and type of clay.  The variables are infinite .  A glaze that works for one potter may not work for another with slightly different materials or conditions.  When I started getting good Flambes I felt like I’d hit the big jackpot after 30 years of gambling addiction.  There should probably be self-help groups for potters.

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2013 Dawns-End of the World Postponed indefintely

Another milestone passed and in spite of widespread hysteria and general craziness over the end of the Mayan calender the world continues undisturbed.
All my projects are moving forward except the colored clay block. When will I find time for my art? When will I have enough coffee cups to feed the insatiable tourist market ? (never) When will I finally get tired of making gorgeous Flambe glazed pieces? (probably also never). I’m still refining my oil firing system. Seven successful glaze firings so far. Lately my fireboxes are clogging up with carbon build up-big fist sized chunks of carbon from too-slowly burning oil that block the heat flow through the firebox. So I’m doing another rebuild to enlarge the fireboxes and provide more air space. I’d rather be making pots but I estimate that I’ve saved around $2000 in fuel since starting to fire with waste vegetable oil so this project is worth it for sure. Also I’m enlarging my burners to get more air in the fuel mix. When my system is perfected I’m going to post it on YouTube. Here’s some recent Flambe pieces. Click on image to enlarge. Reply to my email, too much spam on the blog.

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Colored Clay Fish Block

Finally, I’ve cleared my studio enough from my backlog of unfinished pieces (from my oil firing delays) to embark on my next series of colored clay pieces. I’m constructing a new block and as I work I’m again struck with how unique this process is. I’ve come to recognize that for all the infinite possibilities that clay holds there are areas where potters are handicapped. We tend not to notice because of the multitude of techniques of forming, decorating, glazing and firing. There is more than any of us can explore in a lifetime. But some things are hard to do. Creating images is often challenging and detailed images require meticulous and time consuming processes. Color creation often has severe limits. Glazes are limited by chemistry to a fairly simple palette. Mixing colors is only possible in a painterly way, is often unsuccessful, and results in a distinct brushed look. Few potters are ever trained in color theory because we have so little opportunity to make use of that knowledge. Colored clay can be mixed and blended like paint pigment. Hue, value and intensity can all be worked with. Also very fine detail can be developed in a reasonable amount of time. My favorite thing about this work is that it’s all clay technique, not decorating, glazing, or firing. I got into ceramics because of the wonderful plasticity of clay. Decorating and glazing were necessary evils. I mean, SERIOUSLY, what potter starts out saying “gosh, I really want to mix up 10,000 glaze test tiles, what fun!”
Anyway here’s some shots of my new block in progress, click on images to enlarge:

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Flambe Heaven

I finished my first really successful firing with oil yesterday and today unloaded some of the most beautiful Flambe glazed pots I’ve ever seen. I’m so excited and happy. I’ve never gotten this high on my art before. Building the fireboxes from 2800 degree firebrick was successful even though a couple of bricks cracked. My Flambe show starts in a week. Here’s my write up for the show and a couple of pieces.

The Art of Flambé

There many rare and exotic glazes in the world of glaze nerd-dom. For thousands of years potters have sought the secrets of glazes such as Copper Red, Blue Celadon, Zinc Crystal, Oil Spot, Hare’s Fur, Red Shino, Imperial Yellow and more. One of the most difficult glazes to produce and one of the most beautiful is the Flambé. Flambé glazes were first produced in China around 1600 and became very popular in China and Europe in the 18th & 19th centuries. Flambés are fired in the range of 2200º-2400ºF. A Flambé is colored with a small amount of copper to produce rich, variegated surfaces in shades of red, plum, and fuchsia. Why are they so rare? Glazes are the combined result of many variables. Chemistry, temperature, kiln atmosphere, firing time, type of clay, and application technique all have to be just right to produce a beautiful Flambé.

I’m a glaze nerd, I admit it. I have been fascinated with the endless possibilities of glazes for over 25 years. I have laboriously mixed many thousands of glaze tests, most of which have been failures. But every now and then I get lucky. A year or so ago I began experimenting (again) with glaze recipes from a long out of print book. Imagine Harry Potter poring over a dusty old book of magic in the dingy basement of the Hogwarts library and you’ll have a picture of me reading obscure glaze books in the dead of night, trying to unravel the secrets of the world’s most beautiful glazes. I had tried a few of Saunders’ glazes many years ago with no success. In the past ten years I have improved my understanding of copper glazes and this time around my tests started to look pretty good. Now I am infatuated with Flambés and don’t want to use any other glazes on my pottery. Eventually my restless spirit will move on and I will explore other ceramic realms but for now Flambés are my passion.

The kiln I use is designed to fire with propane, a very expensive fuel in Hawaii. Three years ago, in an effort to cut costs, I began experimenting with WVO, waste vegetable oil (from restaurant deep fryers) as a substitute fuel. It has been a long and difficult process to design and build a reliable burner system using WVO. I have had many failures along the way. In my quest to save money on firing I have spent many thousands of dollars and expended countless hours of struggle. I have just about worked out all the bugs and have completed a couple of difficult but successful firings using vegetable oil. My success with oil firing in my latest firing is concurrent with my success with Flambé glazes, I don’t know why, some esoteric destiny pattern perhaps. WVO is much hotter than propane. It is easier to reach higher temperatures and I have raised my firing temperature to 2360º. The Flambé glazes are more vivid at this temperature and more fluid. You can see the patterns made by the flowing, molten glaze in many of these pieces. Every type of firing has its own characteristic energy. I’ve fired with electricity, wood, propane and now vegetable oil. Oil seems to me to have a high, vibrant energy that is well suited to Flambé glazes. And it’s “Green.” How cool is that?

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Another Firebox Meltdown with oil

I did a bisque firing with oil and had more problems with firebricks melting. Had to cut the firing short at 1650 as the fireboxes were collapsing. Oil is hot! The brick fragments are from 2300 degree firebrick and 3000 degree castable refractory.

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Flambe’ glazes

I’ve been working for many years to perfect an oxidation red glaze using silicon carbide in the glaze as a local reducing agent. Almost no potters work this way because of the dominance of reduction firing at cone 10. Being self taught, I was never steered down the path of reduction firing and for the last 25 years I’ve been firing in oxidation at cone 10 in gas, electric, wood and now veggie oil fired kilns. I’ve been getting some good results with Flambe’ glazes lately. These are an exotic variation on copper red glazes that are plum to orchid purple and often have beautiful variegated surfaces. Here are a few from my 8-26-12 firing.

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Island Reality (oil firing redux)

I just spent 10 straight days trying to get the 5 hp motor on my air compressor that drives my oil system working. It’s now in a shop in Honolulu (76 lbs, $60 shipping each way from Kauai.)
A new motor would be good ($500 in LA $250 to ship UPS or a 2 1/2 week wait for it to come by boat.) I found one in Honolulu but it got sold the morning I called so I decided to try to have mine fixed. I have more than 2 kiln loads of glazed pots waiting to be fired. Alchoholism is looking more attractive every day.

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Vegetable Oil Firing success at last

For about the last 3 years I have been working on converting my 24 ft propane updraft kiln to fire with WVO, waste vegetable oil aka french fry aka used fryer oil from restaurants.  Converting a kiln with no fireboxes is harder than building one from scratch.  Although it’s nice that this is a green, renewable fuel my primary motivation has been economic.  The oil is free while propane is currently $6.50/gal on Kauai.  Propane has been my biggest expense, $300-500/mo.  Although there are a few potters on the mainland using oil everybody has a different approach and there is no ‘manual’ for how to build a functional system.  Everyone who uses oil is an inventor/tinkerer who is willing to start at the bottom of the learning curve and solve the problems that come up when using oil.  I count myself in that group, any normal person would have given up long ago but it seems that every time I give up the universe hands me the next key to the puzzle and I soldier on.

I was originally inspired by Hugh Jenkins, a glass artist from Big Island (Hawaii) who runs his kilns on oil.  Based on his ideas, I envisioned and built a hybrid system combining propane and oil.  It was a miserable failure.   After a year+ of struggle I gave up and went back to propane.  A while later I connected with Jon Faulkner (jonfaulknerpottery.com) in the Bahamas who is doing salt firing with oil.  He has lots of info on his site about his system and I copied his system and again met with failure though there did seem to be some moments of success.  I tested his burner design in my hot front yard in a firebox that I built to see if the two firebox flues would produce the same amount of heat.  My burner worked in the yard and I measured the two flues to be very even up to 700 degrees.  I then built two fireboxes and burners and tried out my system but my burners wouldn’t light.  Despite using a propane torch as a lighter great clouds of disgusting unburnt oil vapor filled my shop, yucchh!  Several more failed attempts followed.

My next angel arrived in the form of an Alaskan customer who walked into my shop about this time.  He had been a home heater and burner designer and installer in Alaska for 25 years.  He talked with me for quite a while and I learned that oil needs to be heated, at a bare minimum, to 80F or it will not burn, even if vaporized.  150F is MUCH better and hotter than that is more better.  Many users heat oil to 200-400F before burning.  He found videos of burner designs on UTube that led to my current design with a heating coil on the front of the burner.

Mcraine WVO burner 7-30-2012

This burner works and it works great!  I use a small amount of propane at first to heat up the coil, then introduce the oil and compressed air.  Once the oil ignites (5 minutes) the burner heats up quickly and works very well.  NOTE:  I DON’T recommend the quick release air connection for propane shown in the picture!  It leaks when connecting and disconnecting and I’ve had a couple of fireballs as a result.  I’m looking for a better quick connect for the propane.

Oil is hot!  WVO has about 140,000 btu’s/gallon vs. 95,000 for propane.  This burner can produce up to 400,000 btu’s/ hour!  My standard propane pipe burners were 50,000 btu’s. I replaced four propane burners with one of these oil burners.  I built fireboxes to distribute the intense heat.  My first fireboxes were made from  2300 degree firebrick.  I destroyed them in an hour.  The bricks melted and broke.  My second fireboxes were 26oo degree fiber board. they held up better but still collapsed.  My current fireboxes are 2800 degree brick and 3000 degree castable refractory backed by ceramic fiber.  These seem to be OK so far after a couple of tests and a full glaze firing to cone 11 (2300F. )

My first successful firing, 7-15-2012,  produced some really nice pots.  Oil feels like it has a higher vibration than propane.  I’ll probably recover my expense and time in a couple of years.  Meanwhile, no more propane bills.

My blog replies are spammed out.  I don’t read them.  Just email me at mangodean@yahoo.com.

 

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FInished teapot and other new work

Here are some images of new pieces in my colored clay series that I plan to enter in an upcoming contest.  I also lost two large vases that cracked from heat stress in the firing, “haste makes waste.” I typically fire up at 400 degrees/hr with no problems but these large pieces were too close to the burners.

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Colored Clay teapot project

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