Jump to content


Member Since 11 Mar 2013
Offline Last Active Apr 22 2016 04:21 AM

#105519 How To Reveal Lace Texture

Posted by earthfan on 22 April 2016 - 04:24 AM

I notice that you have pressed lace into the ornaments. What looks even better is to press the lace into a slab of clay about 8mm thick, wait for it to firm up a bit, then remove the lace. Dry the clay slab and fire it to bisque. Use that as your mold for lace texture. It is easy to do on a small scale and your pieces will look as if they have real lace stuck on them.

#100833 Spodumene

Posted by earthfan on 28 January 2016 - 09:12 AM

The spodumene supplied by the Greenbushes mine is a fine sand that is 88% spodumene and 12%silica.  I fired a little bowl of it to about cone 7 and it converted to beta spodumene, puffed up and turned into a fine pink powder. It did not melt at that heat and didn't even fuse to the bowl it was in. Spodumene has one molecule of lithium oxide to one molecule of alumina to 4 of silica, so it is like feldspar, but with a lower proportion of silica. Spodumene has a negative co-efficient of linear expansion. It doesn't shrink when fired, it gets bigger.


Lithium carbonate is Li2CO3 and is slightly soluble. That is what you need to spray on the raw clay to get a sheen.


"Ceramics Monthly" of February 2015 has an article on spodumene.

#94272 Is It Ruined?

Posted by earthfan on 16 October 2015 - 12:10 AM

I like the dirty dish story too. Reminds me of an acquaintance who fed a roast dinner to 35 people one Christimas, She roasted a leg of pork, a leg of lamb and a turkey, together with trays of potatoes, carrots and pumpkin in her front-loading kiln.

#89085 Meat Grinder As Pugmill?

Posted by earthfan on 17 July 2015 - 10:26 PM

I don't have any canvas bags, but the legs of old jeans work just fine as long as they don't have holes in them. A friend has a jeans leg attached with some kind of clamp to the outlet of her wheel splash pan . The sewn up hem end sits in a bucket. All the throwing slip and turnings go into the jeans leg. When the jeans leg is full, she ties up the open end and lets it stiffen. The cut and slam method of wedging doesn't require very much strength. You don't have to lift the whole lump of clay, only half at a time.

#88392 Crazing

Posted by earthfan on 06 July 2015 - 11:53 AM

Crazing is the bane of my life, even though I work in stoneware. The thing with earthenware is that the glaze will eventually craze, even though it doesn't do it in the kiln. With use, the absorbent body takes in moisture from the air and dishwater, which makes it expand slightly, which stretches the glaze so that it splits. 

#86399 Selling Imperfect Pots?

Posted by earthfan on 02 June 2015 - 07:14 PM

Refiring at a slightly lower heat would remove the appearance of grinding. Refiring is also an opportunity for brushwork decoration. I found it much easier to paint designs on glaze that was already fired. When firing pots that are already vitrified, you have to go very slowly past the quartz inversions.

#79448 Turned Foot Rings On Mugs; Elegance Or Affectation?

Posted by earthfan on 15 April 2015 - 11:04 PM

I don't like washing bare clay on domestic ware whether it is for serving or cooking. So I cut foot rings. They look better and allow most of the base to be glazed. The only disadvantage of the foot ring is its tendency to collect grotty water in the dishwasher. I cut V shaped chinks in the foot ring, but that spoils the look. What I would like is the foot ring on a plastic mug I own. It has a foot ring of tiny half domes, but I can't think of any way to apply them efficiently to thrown cups. Any ideas?

#61394 Sitter Shutting Off One Cone Before Supposed To...

Posted by earthfan on 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."

#58348 Encouraging Glaze Movement?

Posted by earthfan on 12 May 2014 - 07:03 AM

A line blend is a series of mixtures of only two ingredients. In this case, one ingredient is the mixed-up glaze without the silica, and the second ingredient is the silica. A triaxial blend is a series of mixtures of three ingredients, while a quadraxial blend is a series of mixtures of four ingredients.

There is a video on Ceramic Arts Daily of John Britt demonstrating a line blend; and another video in which he demonstrates a triaxial of three different stains. 

#58123 Encouraging Glaze Movement?

Posted by earthfan on 07 May 2014 - 10:21 PM

All my ceramic chemistry research suggests that it is alumina that stiffens the glaze. If you could replace some of the clay with silica, the glaze should move more. You would have to do many tests. I would start by mixing up and sieving a 100 gram batch with only 5% of the clay that is in the original recipe. Then create a line blend with silica. Dip a little test ring and label it, then add 4% silica. Stir it up well and dip another little test ring and label it. Repeat a couple of times. You have to remember that each time you dip the test ring, you are diminishing the quantity of glaze so adding 4% is actually adding somewhat more than 4%. But for your first firing it is very informative. In your next firing you can be more precise.