Questions & Answers

 

Here are some questions some of the visitors to my site have asked via email, and my response to them.  If you have questions about my work, email me.  I will try to respond ASAP.

Thank you, Ken


 
On Jul 28, 2013, at 6:18 AM, Jim Ginavan  wrote:
 
Thanks so much for sharing. Your website is quite informative but I do have one question. When aluminum foil sagger firing. Do you allow the work to cool completely in the kiln or do you remove at a certain temperature to remove the foil and introduce oxygen to the piece?

 
Thanks again for your insight! I have found this process to be very exciting. I have a tendency to learn how to do something and then start to play the what if game with it. What if i did this or this to the work. Did that with my evolution of drawing and printmaking... only seams natural to carry that into ceramics.
Jim,
Chances are pretty good that oxygen is getting to the work in most cases as the foil splits, turns to ash etc.  If the foil is still silver and completely intact then it probably didn't get hot enough.  You'll still get results but they could be better as the chemical salts become more volatile by 1400 F.
I've pulled and opened work very hot to do horsehair technique, and just to get another firing done when time is an issue.  I see no difference in the final work.  When pulling hot, it's exciting to see the color development occur as the work cools, but be confident your clay body will handle the thermal shock.   

 
I love that game!  We can't help ourselves, as teachers, artist, designers, craftsmen and explorers, we have to ask those questions and experiment with different materials .  The discoveries we make generate new questions and and help advance our artwork to new, exciting and interesting levels.

 
I had such a discovery that night, trying something I had been thinking about for quite some time and something else altogether different that just dawned on me at the time with really exciting outcome.  I can't wait to share this new technique at the Potters Council in Oct.

 
Good luck & be fearless in your exploration,

 
Ken Turner
 

I was contacted by Alexander Kostrikov, Laboratory for Comparative Planetology, Vernadsky Institute, Moscow, Russia, Via the Internet and asked to perform some small test for him in the interest of science.  Alexander requested I throw a plate, promote "S" cracks, document with photos and share the results with him.  We had limited correspondence but were successful with the experiments and the details.  My tests helped Mr. Kostrkov to prove his theory that spirals in the North polar cap of Mars are evidence of an ancient Ice sheet collapse.

Alexander presented his findings to planetological conferences and sent me his abstract.  If you would like to read it click the link below.  

May Be You Can Help!

"I did not publish my paper in a scientific journal yet, but put its abstract (the text I sent you) in Internet. The problem is to provide a professional mathematical (computer) modelling of cracking in rotating body. (It seems this is a 'terra incognita'!) I am looking for a specialist now. So, you struck home. Maybe a ceramic scientist will be interested in this problem."

Link to A. A. Kostrikov's Abstract

A High school student emailed and asked for an interview for his part of his class project.  I invited him to my studio, had a nice visit with he and his mother and answered his questions online.   Click here if you would like to read it. 

KC Writes:

First off, thanks for a very informative website!! Your work is spectacular!!
  I had been thinking about using lusters on raku pots but had no ideas about how to do so---- and then I found your website!! Spectacular work!! 
    I do have a few questions about the application of lusters and their relationship to firing( color changes, etc.) with Raku glazes-- that perhaps, you can help me with or direct me to where I can get more information.
    First, I have gotten many conflicting ideas about the use of lusters and raku glazes( when you apply them-- which first,etc.) Most of this conflicting info is from raku artists who have heard about using luster but have never done it, themselves.
My understanding at this point is:
1) apply the raku glaze and fire.
2) Apply the lusters at a later luster firing in electric kiln.
3) Raku glazes that have copper in them-- may change coloring during the luster fire.
 
     Am I right about this order? Some people thought that I should apply the lusters first-- then raku fire-- but that doesn't make sense to me. Do you have any thoughts about this?
    Also, if I raku'ed with a non-copper glaze such as a white or clear crackle-- would the appearance change with a luster fire after?  Are only the glazes that contain copper-- are ones that would change color in the oxidation fire of lusters?  If I use glazes that do not contain copper and add a luster glaze---how much change is there is the original raku glaze appearance?  Is there anyway to calculate or predict the changes in the raku glazes? What about the properties of Gerstley Borate, Bone ash and N.S.? 
    I know that these are many questions-- and perhaps you do not have the time to answer all of them- but maybe you could direct me to where I could find answers.  I do know that one of the delights of raku is it's immediacy and it's unpredictability. But any information about using luster on raku pieces would be greatly appreciated.
    Once again, thanks for a very informative website and a look at your wonderful work!
Kc Camp

 

Hi Kc,
 
Wow, that is a lot of questions!
 
First I must tell you that most of the work you see on my website is highfire porcelain and some stoneware.  Only the altars and a few of pots the are raku, and the gold on the altars is gold leaf.  I have applied luster to raku and smoke, or pit fired pots with success in the order you described.  I have also tried to fire luster to raku pots during the raku firing.  It can be done, but great attention must be paid to the work or you will burn out the luster.  If you want to try this try it on a white or clear crackle piece that has already been fired.  Apply your luster, place it into the raku kiln so that the luster can be seen, and begin to fire.  You should be able to see the luster turn gold or what ever at red heat.  Pull the piece before it gets too hot or you will lose it.  Treat it as you would any other piece pulled from the kiln (post fire reduction) or try letting it cool without reducing.
 
My advice to you is to just go for it!  Experience is the best teacher, and if you read too much info. you may not try something that could lead to some very exciting discoveries. 
 
Good luck,
Ken
PS. Maybe I'll read your book on this subject someday!

 

 

Beth, from Texas writes: 

Thanks for writing back! Have you heard of James Watkins? He uses a certain raku glaze that we have been trying to duplicate: 80/20. We can't quite get it. Do you have any suggestions? We'd appreciate the help. Thanks!

Hi Beth,

 80/20 is a very old and reliable raku glaze formulated by, or credited to Paul Soldner. 80% gerstly borate, 20% Neph. Sy. Many other raku glazes have been created using this base and adding coloring oxides, like Copper Penny, and Copper Sand.  And sometimes slight variations of this base are used.  The 80/20 is a beautiful clear crackle. Try using it on a white clay body or on a clay body with a white Tara sig. or porcelain slip. The key to achieving a good crackle is to remove the pot from the kiln and have great patients before placing it into your combustible material. You must listen carefully for the crazing to begin. If you want finer crackle patterns you can blow on the surface. If you are still not getting crackle, then you must change your clay body. The clay and glaze are compatible, this dose happen but not often. I fire to cone 06 this works well for me, even as low as 08 for some glazes and desired glaze effects, but never over 05 with the glazes I use.  Also you must find that happy medium where you get the desired amount of crackle but the pot has not cooled so much that it will not ignite the combustible (I use news paper) if this happens be ready with a torch! The crackle will show up but the intensity will not be there. The first cracks will be the largest ones, they should be very black. a smaller network of crazing will appear with a lighter black and a third very fine network will be a very light gray. You may also see an even finer pattern show up later but it will not be smoked. These large to small, black to clear crazes add depth to the surface of your work, and make for a very rich and interesting piece. James Watkens, the name rings a bell but I can't place his work. I'll look him up when I get the chance.  By the way, the raku bottle in The Gallery on my site (2nd to last photo) is 80/20. White stoneware with porcelain slip. Good luck with the raku and let me know when the site is up!

 Ken,

PS. You may already know they have stopped mining Gerstly borate and the supplies have been depleted. There are substitutions on the market (Laguna Borate, Cadie Cal, Murray's Borate), to name a few, but much testing must be done for glazes containing high amounts of GB.

Thank you for the information on 80/20! If it's not too much to ask, what glaze did you use inside of your "Ritual Bowl," the last picture in your gallery photos?  It's beautiful!

 Thank you, the glaze is called "Dolphin Blue", it's published in Robert Pipenburg's book RAKU POTTERY, Buy the book it's the Rakuists bible!  Measure parts by volume: 7 - Gerstley Borate 3 - Bone Ash 2 - Neph. Sy. 1 - Cornwall stone 1 - Copper carb. 3/4 - Cobalt oxide This is always a beautiful glaze. The Spirit Bowl or Ritual Bowl is porcelain.

Ray, from San Antonio Collage, CA, writes:

My name is Ray and I have a paper to write. I chose a your Fertility Plate to write my paper on. So if you could answer a few questions for me I would greatly appreciate it. 1. What sort of precious metals did you use for this particular piece? 2. What inspired you to do this piece? 3. What does it mean? 4. How much does this piece cost? 5. How long did it take you to complete the piece? I can't think of any other questions to ask but if you have more information that you can give me about the piece I would greatly appreciate it. Thank you very much for you time and help.

Hi Ray, I'm glad you have an interest in my work. You have some good questions. My answers will be as short as I can make them because I don't type fast and must get to the studio. I use a product produced by Engelhard Hanovia called Liquid Bright Platinum and Liquid Bright N Gold 11%. The metals are suspended in an oil based solution, when fired at a very low temp. (1341 F) the organic matter burns off leaving a very thin coating of gold fused to the surface. Hanovia claims the gold is 23K purity.

 I am inspired by the things I find beautiful and enjoyable in life. The "Fertility Plate" draws parallels between the creation of life, life giving forces, and the creation of in-adamant objects. Man's need to reproduce and his need to be creative are, I believe very closely related, if not one in the same.  What dose it mean to you?  Once I have created the piece and let it go, it becomes more important to me how those who come in contact with the work, interpret it and feel about it them selves.

The two plates you see in The Gallery on my site are 22" dia.  and 26"dia.  I've been working with clay for 27 years. That plus a few hours is what it takes for me to create one of these platters. The loss rate is also very high with these larger platters.

Good Luck, Ken

Hi Ken, I have a question for you on the silver and gold that you fire on your pots. If I fire a raku glaze on to a pot and I want to add gold to the pot after the raku firing will I loose my raku colors when I electric fire to the proper cone temp for the gold highlights . The gold is not as high a temp but 1200 to 1300 may change the raku glaze as well am I right. HELP!!!!!!! Julie

Hi Julie,

Yes, you are most certainly correct.  Firing the gold onto the surface of a raku pot will most certainly change the look of the glaze. Especially if you are using the copper bearing glazes, and it sounds like you are.  Not only will the glaze change but you will lose the beautiful black color of the clay.  Try some experimenting, you will likely discover some interesting results.  Years ago I smoked fired some work that I had added gold to and they came out gorgeous.  You can either pull the pieces directly from the luster kiln while still very hot (1100 to 1300 F), or reheat at a later time and reduce them in your reduction cans once again.

Good luck, your journey will offer you many new and exciting possibilities, be courageous, embrace them.

hello Ken,
My name is Andrew Vickery.  I'm a college student from Dallas, GA.  I
have access to natural clay sources here and I wanted to ask you if you
could possibly send a diagram to me of any wood-burning kiln plans that
you may have.  I would like to try and build a small one and I have never
found a detailed description.  Either that or you could possibly tell me
of other online resources that are useful for this.  I would really
appreciate it.  Good work by the way!
Thanks,
Andrew Vickery

Hi Andrew,

  A wood kiln is a very different beast altogether.  I don't have any plan drawings, but here is some advice; don't apply standard perimeters for gas kilns as far as air intake flue outlet ratio.  Wood gas expansion is enormous, and needs to be able to escape, so a wide flue is recommended.  It is much easier to reduce the air intake and dampen the exit than it is to expand it once the kiln is built.  My experience (which is not great with woodfire) tells me that very little damping is necessary.  Build fire box lower than floor of kiln if possible.  I built a 110 cubic foot Sprung arch kiln for woodfire, (not typical, but works well) the 7' span had I believe a 9 or 10" rise.  The firebox is in the kiln; only about 6" baffle to prevent the draft pulling across the floor.  The pots act as the baffle when stacked.  The shelves are arranged to direct the flame path back and forth before exiting the flue.  The flame goes to the top of the arch follows the arch down to the top shelf which is against the wall blocking the path and redirecting the flame across the shelf back toward the flame and down to the next shelf which is not against the wall and pulls the flame path back.  This zigzag shelf pattern repeats it's self from bottom to top and allows for even heat and ash distribution.

  If I were you I would contact Nils Lou, this is his web site; http://www.linfield.edu/~nlou/ his email address is available there.  He is wise in many ways and has many answers. 

Look in the latest Ceramic monthly, June, July, and August 2002.  On page 110 and 112 Nils answers some questions about wood fire kiln construction.

Good luck,
Ken