The volcano erupts again!

Another week has passed and I have looked over my results from the last firing. I made some nice pottery last week but didn't tell you much about the bricks. They were bad! Very over fired. I have made some changes and went at it again. My results are much better this week.

I had too coarse a mix of glass fragments in the clay. That made for glass to melt out of the bricks.
That along with placing them stacked ontop of eachother also supporting the weight of the kiln top too much. The heat destroyed them into glued together ckinkers.

I lowered the entry point of the chimney flue and added a metal door to the front of the firebox.

I also took the stacked weight off of the green bricks by putting firebrick support posts inside the heating chamber to hold the kiln rooftop up. The new clay/glass mix is still 50/50, but the glass is tripple sifted to the mesh size of wire window screen.

This is the result of that effort!

My last name is Hendrix, but my wifes family name is Kennedy. So her brother asked me about bricks with their name on them. All the bricks passed the water submersion testing with no ill effects.

First successful pottery made! In the Volcano.

Here you go! Made out of field clay and glass dust.
They all have ring to them and passed the water test.
This is my beginning! Very excited now.

With the help of my kids I now have named this kiln the "Volcano"

Wood Furnace Boiler Heat Update

Ive been doing alot of work on my wood fired heater boiler since last time I posted about it. Here are a few pics of the progress.

I did it! I have made fully fired clay bricks.

I finally have been able to make a hard, durable brick. I was lacking a flux that would work in the short firing time frames I am forced to use. Salt and lime didn't work fast enough. But ground up glass dust did. What takes pure clay several days firing to do, I now can do in 1 day!

Old scrap glass from bottles, windows, and television picture tubes is smashed down in my mixer with heavy round stones.

Then I sift the crushed glass down to remove all large pieces

before adding it to the clay to press out bricks.

I am using a 50/50 mix of clay and glass.

Then I fire the bricks same as before.

The three bricks to the left are regular clay bodies for a control. The forth, sixth, and seventh are 50/50 red field clay and glass. The fifth brick is 50/50 grey streambed clay and glass.

The controls were not vitrified and crumbled easily. The red clay/ glass bricks were solid and passed water absorbtion testing averaging 11% and maintained full strength. The grey streambed clay / glass brick had absorbtion at 22% and split minutes after submersion in a bucket of water.

I attribute the failure of the streambed clay brick to the high level of lime pebbles in the clay mix it was made of. The lime swells as it absorbs water causing fractures in the clay body of the brick. I will work on removing the lime pebbles for the next tests as I really liked the near white look of that brick and would want some of them to hold up for me.

Third kiln design and brick firing.

Its my biggest kiln yet. Double the capacity of my last one.

Hottest yet! It takes alot more firewood now too.

Look at the glow. I need to get some sort of pyrometer or cones

to know better what temp is being reached.

Notice the white bricks. They along with the pottery are from streambed clay instead of red field clay. I next will be working on fluxing agents like lime and used glass to improve hardness and vitrification of the bricks throughout.

Bricks from my latest wood firing.

Here they were before firing.

After firing.

Here are the results! 12 good light reds, 11 underfired soft salmons, 5 clinker ringers, 9 junk clinkers.

These were the best of the whole batch. They all had 'ring' to them when tapped. I still would like to see them fired a deeper red and a bit harder. But its hard to get it just right without going too far and making cracks in them.

Overfired 'clinkers. Taken from the back and the lower part of the kiln.

Firing up the brick clamp part 2

Saturday morning I went out to find the fire out but for some coals in the firebox. The bricks were still very hot though the glow was gone. I restoked up the fire and had it glowing again in about an hour. During that time I added a curtan wall of red brick around the firebrick to help hold in the heat that was excaping from all the cracks. It made a big improvement in the overall heat and glow inside.

Black sooty smoke is bellowing from the top just after I put more wood on the fire.

After about 10 hours I shut it all up and let the cooldown begin. Sunday I opened it up to see the results.

Out of 24 clay brick I had made and burned in the clamp, none broke! A few had cracks. They were in various states of firing. Over half were underfired to different degrees. A few had glazed overheated spots on them. And six or so had the nice orange almost red look from the iron oxide in the clay. About a third had a noticable ring to them when tapped instead of the thud when tapped of an underfired brick would.

Overall I rate this firing as a success. I made marked improvement over last years attempt. I got rid of the milky chalky haze last years bricks had too. None of the bricks from the last try were very tough or had a good ring when tapped. These had many that did. Just wait for my next try!!!

Before and after!