Friday, April 19, 2013

Lost, Found and Wiser

Lost - one set of blogging Mojo, due to huge stress when my man came off his motorbike at Easter and suffered nasty injuries.  I am a coper but that kind of 'fried me' energywise.  I kept thinking I'd throw together a paragraph or two, a quick snap of something clay related to share but no, it was long gone.  I couldn't trust myself to make anything new either because the heart was not in it.  I did lots of teaching in High School though.  Teenagers are so funny with clay, especially boys.  I think I have found my Mojo again though so I must be feeling more rested and optimistic.

Found - an explanation for why my new kiln is overfiring.  This kiln is the old one I bought from the local primary school when former Prime Minister Kevin Rudd decided to provide a new kiln and art and music room.  The casing was rusting from the inside out so I had it refurbished and recased by Kilns West in stainless steel and unlike any other I've owned, it has elements set into the door.

Wiser - do you know that classic bit of kiln wisdom where you do a test firing to work out your cool and hot spots? You set a cone pack on every corner of every kiln shelf to gather intelligence on what is actually happening in the kiln.  That's what I've been taught by potters who are top of their games why ignore such well informed advice?  People baulk at using up all those cones because of the cost but cones aren't that expensive and they provide so much accurate invaluable information.
So I set cone packs on each shelf in a lightly packed kiln.  I only had a few bisque bowls, glaze tests and boxes I was prepared to risk in a test firing, we all know a tightly packed kiln gets the best distribution of temperature.  It was getting much hotter inside than the temperature gauge indicated or the Harco programmer was set for ie 1280C.  I noted that the kiln took a lot longer to cool down after the firing cycle than I expected - an indication of a well insulated kiln.  My previous kiln had so much rust it got pretty hot on the exterior painted casing and the orange glow around the door gap was pretty obvious too, I could observe it down in the studio from my kitchen window.   One door hinge had broken off the main casing, my God how I nursed that thing along for years.

I consulted Kilns West by email and showed them my firing schedule and photos of the cones.  I reckon it is the heatwork within the kiln being greater than I'd anticipated and I will modify with my firing schedule a little to get to 1280 and not 1300C+ as I seemed to have achieved.  I had items in Southern Ice Porcelain in there and they became very translucent, glassy and vitrified, almost like Depression Milk Glass though I also got some bloating in the bowls.  It wasn't recycled clay.  So ... on to the next thing.
Come with me now to the Mud Colony group of Bloggers to see what the others have been up to.  

No comments:

Post a Comment