Saturday, February 26, 2011

Christchurch Earthquake

Our thoughts go out to everyone in New Zealand and overseas who has been affected by the recent 6.3 earthquake in Christchurch. We didn't feel the quake out here in Brighton, although it was felt quite strongly elsewhere in Dunedin, and we feel very fortunate that none of our friends and family have been directly affected, but this is a tragedy that touches everyone in New Zealand. At this point, the number of casualties is still rising, and large areas of the city are still missing vital water and waste and electricity services. The response from the Civil Defence and Search and Rescue teams has been absolutely amazing, with teams coming in from all over the world to offer support. has a good page here giving the latest news, and if you want to help out, the best way to do that is probably to donate to the Red Cross:   or the Salvation Army, who are doing a wonderful job providing food and comfort to anyone who needs it.

Edited to add:

A page from the Christchurch City Libraries collection,  showing archival photos of old Christchurch, including Cashell St, Colombo St, and Cathedral Square. A reminder of just how old this beautiful city is, and a small indication of how very much has been lost.

Tuesday, February 22, 2011

Test bottles - oxidised glazes

Yesterday I did an oxidised firing in my gas kiln, using some of the same glazes as I used in the last reduction firing but getting totally different results. I was able to obtain some very nice oribe glazes. From copper carbonate I obtained light blue, deep red and copper greens.  Over the next couple of weeks I want to do some salt glazing in reduction and oxidisation, to see if I can get similar colour response but with a salt-glazed textures.

Oxidised glazes in front, same glazes using reduction in the back
Oribe glazes using different feldspars
A selection of oxidised and reduced glazes.

Friday, February 18, 2011

Testing Times

Recently I discovered that small, two-inch high bottles make perfect test pieces for trying out small amounts of glazes.  They are just the right size to dip into a 100 ml glaze pottle and are very attractive when fired. They look much more interesting than the traditional test tiles and also give me a much better idea of what the glaze will look like on a finished pot.  Making the pots is also a great way of exploring form. I am currently using them to try out variations on some of my favourite glazes  including copper red, shino, tenmoku and celadon.

In the 'lab' dipping a test pot into 100 ml of shino glaze
Test pots arranged in the gas kiln
Fired test pots - shino in front, celadon and tenmoku, copper red.
Different shino glazes, using different feldspars. The one on the far left is my original shino recipe, using washing soda crystals from the supermarket, the second from the left is the same recipe but using soda ash from the glaze room. It gives a more fluid melt and also appears to be really good for carbon trapping. When using these materials I found that dissolving in warm water first made the sieving much easier.
The copper reds - different recipes used over buff stoneware and white clay. Done in a reduction fired gas kiln. I hope to refire these same test glazes in oxidisation to produce copper greens.
A selection of variations on some of my glazes including twenty celadon glazes at the back, twenty shinos in the middle, and twenty tenmokus in the front. Not only am I looking for an attractive glaze, but also how it behaves in the bucket - so that it doesn't 'pack down' like a rock, and is easy to stir, sieve and apply.

Thursday, February 17, 2011

Time out foraging amongst the hedgerows

Yesterday afternoon Katherine and I went for a walk to Ocean View Beach, and then came back and picked a bowl of blackberries from the bushes along the banks of the creek. Somehow the fattest and juiciest berries are always just out of reach!
Wild blackberries amongst the hedgerows bordering the property

One of my celadon bowls, full of shiny, juicy berries.
Ocean View beach looking towards Blackhead Quarry

Monday, February 14, 2011

Small Salt Glaze Test Kiln Construction

Last week I built myself a small makeshift top-loading brick stoneware kiln, that would give me the opportunity to test out salt glaze recipes in small amounts. It is fired initially by wood and then by a diesel jet burner going in at the side. I was able to put it together in one afternoon, using a scaled-down layout from the one that I used on my big kiln. This one has a kiln shelf as a roof and no arches.The walls are a single layer of fire bricks, as this cuts down on a lot of bricks, and should be enough for a small test kiln.  Anything bigger needs to be double brick walled.

It's the same size as my small gas kiln and would make a great hobby kiln/test kiln. I'll be interested to compare it to the small gas kiln in terms of fuel economy. I've used fire bricks throughout (house bricks will just melt at these temperatures) laid on a bed of cinder blocks. The kiln reaches temperatures of over 1300 degrees Celsius, so it is suitable for any kind of stoneware.

Here are some photos showing four stages of the construction:

The first layer of fire bricks, sitting on a foundation of cinder blocks

The second level, showing the firebox and throat into the kiln which runs under the floor.
Side view. This is where the diesel burner goes in, under the chimney. It goes under the floor combustion space before it gets into the kiln.
Top view, showing kiln chamber at the front, chimney, and firebox at the rear. There is a salt port in the top right hand corner, where the salt is thrown in over the flame, in front of the bag wall. This photo shows three layers of bricks in the main chamber where the pots will sit. After this I kept adding layers till I got the finished height, adding one spy-hole in the middle, and a little hole for the pyrometer up near the top. There will be a flue for the chimney at the rear.

Side view showing kiln shelf covers in place, and chimney - I will add a stainless steel flue chimney as well, before firing, to create more draw.

I hope to fire this one in another week or so, with some new salt glazes and subsequent oxidisation and reduction firings.

There are some plans similar to what I used here. They were originally taken from 'New Zealand Potter' magazine but unfortunately I forgot to write down a reference.  Here is a plan showing a cutaway view of the kiln in action: