Long time no blog

It's been a while since I've blogged because I've been fishing a lot and not making pots so much. I do however have the studio in place pretty much. At least enough that I can wedge clay and make pots. So I'm doing that and awaiting the cash flow to complete the kiln project. I'm only short a few hundred bucks, but it's amazing how much a few hundred bucks is when you don't have it to spare.

The great thing is I've been able to get my feet wet with castable cement in the building of a backyard cook center for my mom. We've built a catenary arch kiln style oven with a small arched firebox in the bottom and a level cook top in the oven chamber. I'm pretty excited to finish the piece off this weekend. I'm going over there to build the final frames for the big catenary arch which is going to be the top, sides and back of the oven. 

To build this thing we've used lincoln 60 fireclay, pine shavings, fine and course mulcoa grog, and Ciment Fondu which is a 40% alumina refractory cement. This was used in a 2,2,2,1 parts formula. 

2 Fireclay

2 Pine Shavings

2 Grog

1 Ciment Fondu

We had to substitute some sand to complete the cook top because we were running out of aggregates at the time. We also had to substitute some Portland Type II cement into the cook top because we ran out of Ciment Fondu. So the top of the firebox itself has about 2 inches of good refractory cement, and the top of the firebox layer or cooktop has about 2 inches of Portland Cement. For this application it should be just fine, although I did have the idea that I would burn this thing to red/orange one time to cure it and I don't see that happening with Portland Cement. We'll see how it goes, but I certainly don't want to push the cook top the the point that it fails.

The tall arch we're about to build is going to be a 2" layer of medium density castable just like the firebox pieces were, followed by a 3 inch layer of light castable made with perlite. In the big arch we're going to put holes which will later hold spring mounted bolts for a flange which will hold the doors. There will be two doors on the oven one small one down below for the firebox and one up top for the oven which will be quite large.

Keep it Moving

It's been a period of constant transition for the last year. I've been unable to set up shop for very long because we keep having to up and move. I'd planned this time to stay here for at least a year, but here we are again in a position where we need to move. The current living arrangement has failed to work as intended and I have to give up my two car garage, my huge office and my new garden space that's full of vegetable plants. I'm really bummed out!

So we're looking at places somewhere outside Vancouver. A couple look promising, but no concrete plans as of yet. One little place on an acre in Orchards is particularly interesting, but it has no garage or basement. I could build a cheap out building made of Plastic and cattle panel for a greenhouse and a shop.

The good news is, I have done the research and can now build a large castable kiln for a few hundred bucks. I'll be building the arch frames and ramming my mom's oven by the end of the month.

The bad news is the move is going to cost me all my student loan money and I'll likely lose all my vegetable crops when I go.

Redware

So here I am with 300 lbs of porcelain, and I'm itching to make replica Pennsylvania Redware. The bright red clay with white slip trails covered in a bright amber glaze have me mesmerized into buying a couple boxes of red clay in Tacoma this weekend when I'm up there. The question is will I have the money for the 10 other things I'll end up buying when I go?

http://www.ceramicartdaily.net/booksales/Electric_Wilz-3.pdf

Oven

So I've been testing some castable recipes for my mom's Earthen Oven we've been prepping to build in her back yard. I dug through some old posts on the old clayartcenter.net forum and found several referring to a 4,4,4,1 recipe. My tests are as follows.

#1
4 Fireclay
4 Grog
4 Charcoal (Crushed)
1 White Cement

#2

4 Fireclay

4 Grog

4 Charcoal (Crushed)

1 White Cement

1 Talc

#3

4 Fireclay

4 Grog

4 Charcoal (Crushed)

1 White Cement

4 Pearlite

The original recipe called for grog ranging from dust to 4mm particles and sawdust ranging from dust to 3/8". I can get grog that size, but I had a difficult time finding combustible materials that size range. I can get dust and I can get chips, that's pretty much it. So I figured if I crushed up some of this Mesquite Natural Log style charcoal, I'd get the size range. It worked but I gotta tell ya, crushing much of anything by hand with a 8lb hammer isn't the most fun I've had. 

The Talconic Castable is really close to the original, but I was aiming to have a slightly better heat dispersion. I was also thinking it would cure at a slightly lower temperature. We'll see how it performs through the test I made. It's just a slop brick form, but it's got an arch built into the bottom so I can measure any sagging or warping that might occur. I believe this is only about 7.2% talc by weight, so it shouldn't cause too much of a problem.

My concern is the white cement I purchased. The spec sheets for the material claims it boils at about 1000C. Does this mean the castable will begin to mature near Cone 06? While I realize her oven won't get to that temperature after the initial firing to cure, I'm wondering how these guys are using white cement in Cone 10 castable kilns? Or are they using a different Cement? All the research I've done says they use white cement for earthen ovens. One post I found the guy claimed to have used a recipe from Jack Troy's book published in 1977 called Salt Glazed Ceramics. In that kiln he claims to have used white cement, and fired with salt for 10 years before the arch failed. That doesn't say how many firings. He could have only done 10 firings for all I know. I just purchased the book from Powells Books to take a look. When I do build a castable kiln, or castable slab floor (which I'm doing in the kiln I'm building now) I expect it to hold up for 100 firings or more.

Stay tuned for the results.

Mid-range Porcelain

A while back I decided to buy a box of pretty much every kind of Cone 5 - 7 Porcelain I could get my hands on. There were a few I couldn't get at the time, but I have like 8 different kinds that were in stock. I finally was able to drag my wheel out and get to work.

The first box I grabbed was OH - 6 made up in Tacoma at Clay Art Center. It's got good throwing capabilities, as I thew a 10" cylinder with ease right off the bat. It promptly broke down when I expanded the cylinder. I can't fault the clay too much it is porcelain after all and I was abusing it like a stoneware with grog, trying to push it to failure. 

I did make another pot, and it cracked upon drying. I got a ring crack on the bottom of the pot, which tells me that it dried too long on the bat prior to trimming. I probably need to slow the drying a bit as well, or be more attentive. I could trim quite a bit wetter. I waited until the pot was easy to trim. It had been sitting on the bat it was thrown on for about an entire day. I could probably have flipped it after 6 or 8 hours and then trimmed it between 8 and 12 hours. My garage is drafty but cool because of the big cement slab being directly on the ground. There is also an apartment built above the garage that provides protection from the sun, so it stays cool if it stays shut.

I'll have to give it a few more tests, but I still have many clays to go, so if this one proves to be too picky I've got some 35 mesh Mulcoa with it's name on it. It'll behave, one way or the other.

Bio-diesel

I did some research into fuels recently because of all the recent backlash against bio-diesel. What I found was striking to say the least.

Seed Stock/Oil Yield in pounds per acre

Peanut/764

Canola/600

Rapeseed/600

Safflower/600

Soy/600

Linseed/350

Corn /200

Cottonseed/200

This data was derived from 

Buchanan, G. (2010). Increasing Feedstock Production for Biofuels: Economic Drivers. BRDI , 3.

From the data above it's plain to see the largest yielding conventional crop currently grown in US soils would be peanut.

The basic idea of growing crops for fuel instead of food could be considered a bad thing in and of itself, it's definitely a bad thing to grow a conventional food crop which produces a very low quantity of oil as an oil crop. Yet this is exactly what the US farmers are doing. Corn is the lowest yielding crop that could be planted for fuel.

Under the current methods of production I cannot endorse bio-diesel. I thought I'd be the last one to encourage government involvement in private industry, but the bio-diesel market needs to be regulated. Corn needs to be taken out of the Feedstock for bio-diesel production. 

However there is nothing wrong with using waste oil of any kind as fuel be it corn, peanut, soy, animal oils even. Most of these are low in emissions and have a high energy output. I'm personally inclined to purchase land and become a peanut farmer for the production of bio-diesel myself. The yield being nearly 4 times that of the corn farmer, the comparative advantage is astronomical.

Cerameconomics

In pricing out materials I've found an array of prices for the exact same materials. I'm told it's because some places purchase large quantities of materials at once and have old stock on hand which they can sell me for cheaper. Well I'm here to tell you that the guy down at Georgies who told me that can stick his stock on hand where the sun don't shine. Their prices are outrageous and I see no other reason but that they are price gouging because they are pretty much the only game in town for ceramic artists.

Up in Tacoma however I have been pleasantly surprised by not only the products offered to me by the Clay Art Center, but also their prices. Their customer service is great on weekdays when the boss is there. On weekends the head honcho is out and the place is packed with way to many customers to be effectively helped by the staff on deck. That aside it's a pleasure doing business with Clay Art Center in Tacoma. They provide me with my wet clay, dry clay, raw materials for glazes, and the best part is they're willing to put my order on the back of the next truck headed for Stark Street Studios in Portland for a reasonable fee.