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earthfan

Member Since 11 Mar 2013
Offline Last Active Today, 05:15 AM
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Posts I've Made

In Topic: What Is The Most Interesting Glaze Ingredient To You?

09 February 2015 - 05:08 AM

Re: spodumene concentrate from Greenbushes mine in Western Australia. I fired a bowl half full of the spodumene sand to about cone 7. This is a guesstimate, because although Cone 9 was down, the bottom shelf was seriously underfired. The spodumene in the bowl puffed up to twice its volume and developed deep cracks in its surface. The pile which had been sand was now flour, no grinding required.

I have read in a couple of books that lithium glass does not have a negative co-efficient of thermal expansion. Only the crystalline forms do. But the same books say that up to about .09 of mole, lithium oxide does help cure crazing. More has the opposite effect.


In Topic: What Do You Cover Your Work Tables With?

04 September 2014 - 06:54 AM

In Australia we have a sheet building material that is made of cellulose held together by cement. We call it fibre cement and it replaces asbestos cement that is no longer made. It makes terrific bats and it's the perfect surface for work tables. It is cheap, porous, smooth and doesn't' warp, chip or rot. I have an old pine table that I have covered with builders' plastic with a whole sheet of fibre cement on top. To protect the plastic sheeting I have put some offcuts of my kitchen floor covering between the two layers. You can wet down the fibre cement when you want to get into hand building. When it is dry, it really sucks the water out of sloppy clay, so I use it to stiffen clay that is softer than I like.


In Topic: Does Firing An Electric Kiln With All The Plugs Damage The Elements?

26 June 2014 - 06:46 AM

Our club kiln recently had to have an element changed after not many firings. The person who mended it said that it was because one of our members had been firing with both peepholes covered right from the start - no venting.


In Topic: Foot Rings And Puddles

26 June 2014 - 06:41 AM

I have copied an idea that I saw on a range of plastic containers on sale in Australia. I turn the bottoms flat and mark where the foot rim would have been. Then I stick on small balls of clay, evenly spaced along the marked line. To get the little balls the same size, I extrude the clay from a clay gun and cut equal lengths which I then roll into balls on my damp palm. My computer will draw regular shapes of any number of sides. I print them and cut them out to use as a guide for the placement of the little balls.

Top each ball with a little dab of wax emulsion, and the bowls and cups are ready to raw glaze.


In Topic: Sitter Shutting Off One Cone Before Supposed To...

25 June 2014 - 10:57 PM

Here is a quote from the instructions given by the manufacturer of Paragon kilns: 

"The cone used in the kiln-sitter will not react to heat in exactly the same way as a cone placed upright in the normal position. The weight of the actuation rod and the horizontal position will cause it to bend at a lower temperature than an upright cone. It is usually necessary to use one cone hotter in the kiln-sitter than the cone to which you wish to fire."