More Raku Glaze Recipes

Just a few more Raku glaze recipes.

Soldner's Flat Black Raku Glaze
Gerstley Borate 50%
Borax 50%
Add: Cobalt Carbonate 2%
Add: Red Iron Oxide 10%
Add: Rutile 10%

Soldner's Glass Red Raku Glaze
Gerstley Borate 50%
Borax 50%
Add: Red Iron Oxide 10%
Add: Copper Carbonate 5%

Soldner's Lava Raku Glaze
EPK 30%
Silica 20%
Soda Ash 50%

Its going to be another nice weekend so I'm planning on doing another wood firing. Last week when I was reading Clayart one of the topics was hillside kilns. I had remembered somebody telling me about a "coffin kiln." I think I'm going to try building one of these, a small kiln to fire some raku teabowls. Not sure how I'm going to build it yet. Will just have to dive into the project and get the fire lit. Will post photos next week.

Cast Iron Kiln

Well, here she is in action--My cast iron wood burning kiln.

Looks good, but unfortunately the kiln did not reach temperature. Not a failure though. I learned lots.

First thing and perhaps the most important for me is that if I'm stoking the fire, I'm not doing it on my knees or bending over. I'm going to add another layer of cinder block to the base of this foundation and raise it up.

Another thing is that this kiln is too tight. By that I mean it didn't have enough air or draft. First of all I need to take a piece off the back of my door. The damper works great but there is a piece of metal that restricts airflow. With the back piece removed you'll be able to see right through the four holes and right into the fire box.

Perhaps most important of all I need to figure out how to put a mouse hole into the firebox floor. I needed air hitting the ember pile during this firing.

I only fired 4 teabowls in this test run. They were placed on a round kiln shelf supported by three fire brick. This really reduced the size of my firebox. There was one inch of clearance between the tops of the tea bowls and my fiber board roof. I also used a couple firebrick as a grate system to hlod the wood up off the floor.

When I rebuild this kiln I am putting the ware chamber above the whole firebox. I am thinking about making a small fiber-lined chamber and setting that over the round portion of the firebox. I am also going to stack brick around the exterior of the cast iron firebox because it puts out way too much heat. Looking for some suggestions. Help Wanted.

New Kiln Project

Check this out. All kinds of new stuff for my wood burning kiln building project. One of my friends gave me a piece to an old coal burning furnace. Its cast iron, pretty thick and has a nice door. I am going to use this piece as it sits now. It is actually upside down from its original design but it looked to me to be a perfect fit for a small beehive type updraft kiln.

Plans are to use a layer of fine grog on top of the cinder block, level it out and then place a layer of medium duty hard fire brick on top of that for the floor of the kiln.

Next is to place the cast iron fire box on top of that. Not sure how I'll proceed after that. I'm kind of flying by the seat of my pants with excitement. I'm sure the cast iron will radiate a lot of painful heat so I'll probably layer up some red common brick around the exterior.

Not sure How I'll stack up the kiln ware chamber yet but I'll probably use a roof made of fiber.

My buddy also found some stainless steel pipe that will probably make good chimney material but I won't be using this big piece on this project. Better get to building. Weather is great today. Hope to fire tomorrow or Monday. Gotta run.

Soldner's Copper Red Luster Raku Glaze

Soldner's Copper Red Luster Raku Glaze

Gerstley Borate 80%
Nepheline Syenite 20%
Add: Cobalt Oxide 1%
Add: Copper Oxide 3%

Raku Crawl Glaze

I've been looking for a crawling raku glaze and this one was just recently posted on Clayart, although it is actually a cone 05 glaze from SDSU called San Diego State University Crawl. I'm going to try it this weekend in my wood kiln and will post a photo next week.

47 Gerstley Borate
31 Magnesium Carbonate
19 EPK
4 Borax


According to the person that posted the recipe, "The lower you fire it the more crusty it is (cone 07 or 06) and it is called "Lichen" at that point. And as you go higher it will melt more andbecome a "Crawl" glaze (05) and higher it will be a "Bead" glaze."

Wood Fired Raku Tea Bowl

Here is one of the bowls from my last firing. The interior is glazed with Soldner's Clear and the exterior with Hawaiian Blue.

The interior has really cool light blue speckles in it. Don't know where they came from but they certainly add a lot to the bowl.

The exterior is a dry matt surface with subtly changing hues of blue. Normally in my gas fired fiber-lined raku kiln this glaze comes out a deep glossy blue.

Wood Fired Raku Kiln

Well, I finally built my brick raku kiln and fired it up this past Saturday. I only fired four tea bowls but the main purpose was just to get the kiln built and learn about kiln design and the science of firing. No doublt I learned a lot, but I still have a lot of learning left.

I started with sixty hard fire brick, 10 soft insulating brick and about 50 red common brick. Inside dimensions were 13-1/2 inches wide and 16-1/2 inches tall. I had a small mouse hole that ran from front to back and 2 additional air holes on each side of the front of the kiln. For the roof I used a piece of 2-1/2 inch fiber board and used 4 soft brick to form a square exit flue in the back top portion of the kiln.

I was going to preheat the kiln with propane but found out at the last minute that both my propane tanks were empty so I started with a little bit of wood and some gas. I think I could have saved 3 hours of time had I preheated with propane. It takes a heck of a lot of time to heat those hard bricks and during this time, inbetween stoking, I decided to stack my red common brick around the outside of the kiln. This turned out to be a great idea as the exterior of this kiln, only one firebrick thick, became uncomfortably Hot. The second layer of brick really helped.

Another thing I learned was that a chimney really helps create draft and heat. Three hours into the firing I started to hear the slight roar of the fire. To see what would happen I stacked 3 more layers of brick on the chimney. Within minutes flame was jamming up and out of the chimney creating good draft and a nice roaring sound. I swear I could feel it as well as hear it. The addition of the chimney made it much easier to judge when to stoke more wood. When the flame and roar started to wane, it was time to add another piece of wood. You could actually determine when to stoke just by listening to the fire.

I also decided to experiment with a door in front of the stoke hole. I used a piece of broken kiln shelf. I learned quickly that seconday air holes are a must, but for this kiln a door is not neccessary.

I'm not sure if my mouse hole was designed properly as I frequently used a ram-rod and pushed it through the length of the kiln to keep air flowing through the embers. Will have to do some more research on that.

I used all kinds of different wood to fire this kiln. Some was cheap pine from wooden crates, some was old treated lumber from a deck, and some was a mix of good hardwood scraps from a cabinet shop. The wood was all cut into approximately 20 inch pieces and split into 1 to 2 inch widths. The kind of wood didn't seem to make much difference but the size did--the smaller width the better.

All in all it wa a good firing and a great learning experience. Got so fired up that I have stacked up another mini kiln of a different design. Need about 40 more brick to finish the chimney but hope to fire it this weekend. Stay tuned.

More Soldner Raku Glaze Recipes

Soldner's Dry Pink Raku Glaze
Gerstley Borate 80%
Tin Oxide 20%

Soldner's Curdle Blue Raku Glaze
Gerstley Borate 50%
Borax 50%
Add: Cobalt Carbonate 0.33%
Add: Rutile 3%

Soldner's Copper Red Luster Raku Glaze
Gerstley Borate 80%
Nepheline Syenite 20%
Add: Cobalt Oxide 1%
Add: Copper Oxide 3%

My Studio

Well, this is it. Doesn't look like much but it has a lot of character. It also doesn't help that the picture was taken during our winter thaw, last April.

Its a nice little place about 10 miles from my house and about 10 miles from the city of La Crosse, situated out in a wooded coulee that overlooks a nice trout stream.

The building itself is quite large and used to be a woodworking shop that built everything from tables and chairs to cabinetes. My studio is the "Log Cabin Gifts" gift shop area. In the back is a mini lumber mill with all kinds big machinery that used to cut and mill big trees. All in all its a really interesting place and a perfect environment for a potter.

Cleaned and Sealed

The studio does have a lot of natural light, although the windows could use a good washing. The studio already had a nice concrete floor but I wanted to seal it to make future clean ups easier. It was bone dry and sucked up three coats of Thompson Water sealer.

There is a cast iron wood stove in the corner. It actually came off a train caboose. Will provide some good heat in the winter but I think the owner of the building is going to put in some better heating.

Still lots to do but it will be a fun on-going project.

Pots On The Rack

Just a few of my pots. I have about a dozen biqued tea bowls. I'll be firing these in my wood fired raku kiln. Still hoping to do that in the next few days but it probably won't happen till Saturday.

I also have some high-fired stoneware coffee mugs that I fired in a gas kiln at Viterbo University. I think I've already posted individual photos of the mugs on my flickr
site.

The platters on the lower shelf were all made using slabs of clay and wooden forms that I made. Its a terra cotta clay body and I'll probably just use a simple underglaze decoration around the edges and then use a clear glaze over that.

Soldner Raku Glaze Recipes

I don't know where I collected all my "Soldner" raku glaze recipes from, but I sure have a lot attributed to him. Here are the first few on my list.

Soldner Base Clear Raku Glaze
Gerstley Borate 50%
Borax 50%

Soldner Bisque Slip--Halo
Gerstley Borate 14%
EPK 57%
Flint 29%

Soldner Red Raku Glaze
Gerstley Borate 50%
Borax 50%
Add: Copper Carbonate 10%
Add: Rutile 10%

I finally did stack my brick this past week. I've made a nice little wood-fire raku kiln. I was hoping to fire it Sunday but figured I didn't have enough wood to finish the firing. I collected some more wood that day and Monday morning but got caught in a serious Thunderstorm about 11:00am. Now its back to work. Will fire and post some photos as soon as possible.