Speaking of Nuka

Speaking of Nuka. I got some great information from my friend Lance​ who is continually learning things about the beauty of the world and he creates videos to educate on his findings. He talks about “the living fossil” : Equisetum, which was around in the days of the dinosaurs. It is edible and has medicinal properties but what struck me was that it is very high in silica.

Since rice husk ash is used to create the beautiful nuka glaze. Its color is not easily describable but it has shades and hues of blue, green, white and grey. Every nuka glazed pot is different. I think that the somewhat random nature of the glaze is one of its greatest characteristics.

Look at this beautiful square bottle by Shoji Hamada Sensei using nuka over black glaze. Exquisite!

H39-B_images
Image from Pucker Gallery

 

I have a theory about my own work: that it needs to have an element of control (shaping the clay) and an element of relinquishment (letting the fire do its thing). And since my shapes are so simple, the two need a perfect balance.

Miranda Forrest published a book called Natural Glazes: Collecting and Making in which she describes the glaze using horsetail:

“The first test with horsetail ash alone produced a melted, creamy, greenish glaze with an optical blue in the centre, perhaps the most interesting single land-vegetation result to date. It also mixes well with other ashes and rock dusts. One of the other interesting effects associated with horsetail is carbon trapping during the firing, which gives a dark smoky colour to the glaze in places.”

Very very interesting! I’m all about local materials and making work that is harmonious with nature. After all, nature gives us what we need to live, to thrive and to create. Working with clay is a very primal type of creation for me.

I read somewhere that Shoji Hamada Sensia made nuka using the following

1/3 rice husk ash
1/3 wood ash
1/3 terayama stone ( a high silica bearing feldspathoid)

The highly respected Michael Coffee uses the following:

Custer Feldspar    36.00
Quartz   30.00
Whiting   22.00
OM-4   6.00
Wood Ash (unwashed)   3.00
Talc   2.00
Bone Ash   2.00

Another potter, Steve Mill uses

Silica  40
Rice Straw Ash  50
Feldspar  60

I plan to start somewhere along the lines of the simpler one and work from there. Now… Horseail grows in very wet conditions. It favors clay (how appropriate!) It’s summer. It should be around somewhere. I just have to find it 🙂 (then burn it, then wash it, then test it, etc…)

Testing Results

I’m very happy with the test results. Tweaking these recipes in my cone 8 kiln so that I can get as close to possible before taking up precious room in the big gas fired cone 10 reduction kiln. All of these recipes are based on the Leach 40 – 30 – 20 – 10 recipe method which so far seems very stable. Getting the specific gravity dialed in is important.

Testing rolls right along

So I’ve got all the chemicals I need to make a vast amount of glazes in my simple palate and color range. Testing to cone 8 in my electric kiln so I can tweak it as close as I can before putting it into the big gas fired kiln at cone 10.

  • Zircopax white over temmoku
  • White over Celadon
  • Temmoku over Celedon with a dip into the red iron oxide (FE2O3) as a differentiator test
  • Clear glaze by itself
  • Zircopax white by itself.

Im really excited about these simple glaze combinations. Along with red wild clay slip from the lake and black slip that goes to cone 10 I have a wide range of decorating possibilities to play with.

Previous Celadon glaze tests with incrementing FE2O3 from 2% to 12%


Testing the specific gravity of the glaze with hydrometer.


The only thing I may want to do different is to get more flux into the white glaze to have it run, almost like a Nuka style glaze over Temmoku.

John Britt’s Complete guide to High Fire Glazes has enough information to keep me busy for many years! Big thanks to Jay Benzel of Benzel Pottery for loaning it out to me.

Another thing I was working on was pulling technique and made a nice delicate serving spoon. Beautiful right?!

Not anymore! Haha! The spoon is just a spoon.  That’ll learn me to put stuff on the counter!