Line Blends

Clay= Earthern Red Bisque Fired to Cone 2

Tiles=1hole on left side of tile=glaze fired to cone 6

           1hole on right sideof tile=glaze firing to cone 04

           2 holes on left side of tile=glaze fired to cone 04

           2 holes on right side of tile=glaze fired to cone 6

Chemicals= Magnesium Carbonate and Nepheline Syenite

Magnesium carbonate, MgCO3 (archaic name magnesia alba), is an inorganic salt that is a white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.

The primary use of magnesium carbonate is the production of magnesium oxide by calcining. Magnesite and dolomite minerals are used to produce refractory bricks.[5] MgCO3 is also used in flooring, fireproofing, fire extinguishing compositions, cosmetics, dusting powder, and toothpaste.

Magnesium carbonate is also used in taxidermy for whitening skulls. It can be mixed with hydrogen peroxide to create a paste, which is then spread on the skull to give it a white finish.

This material is very refractory, it does not decompose and give up its MgO to the glaze melt easily. Magnesium carbonate is a good example of the need to consider mineralogy and material level physics in addition to chemical makeup when using ceramic chemistry to adjust and fix glazes. Two glazes may have the same calculated chemistry, but the one using the mag carg to source the MgO will not be melted as much.

When added to glazes magnesium carbonate often mattes them, simply because it is refractory (it is useful at lower temperatures where making a good matte can be quite difficult). Even it is does decompose into the glaze melt, the MgO it supplies is a classic matting mechanism. Magnesium carbonate can also induce crawling because of the decreased mobility of the glaze melt and the exceedingly small particle size of the material increases shrinkage.

Nepheline Syenite= Nepheline Syenite is an anhydrous sodium potassium alumino silicate. Although feldspar-like in its chemistry, mineralogically it is an igneous rock combination of nepheline, microcline, albite and minor minerals like mica, hornblende and magnetite. It is found in Canada, India, Norway and USSR. Thus it does not have a simple theoretical formula like soda feldspar (we have provided representative chemistry of a Canadian nepheline syenite).

Nepheline Syenite has been a standard in the ceramic industry for many years, and is very popular for its whiteness. Nepheline syenite melts lower than feldspars.

Because of its sodium content, high nepheline syenite glazes tend to craze (because of the high thermal expansion of Na2O). Also, since nepheline syenite has more alumina than most feldspars, substituting it into recipes means that on one hand a lower melting temperature is achieved while on the other a more viscous melt results because of the extra alumina.

Process=

1.Took 9 cups and numbered them 1-9.

2.In cup #1 I added 10 TBSP of Mag Carb and 1 TBSP of Neph Syenite

Cup #2 added 9 TBSP of Mag Carb and 2 TBSP Neph Syenite

Cup #3 added 8 TBSP Mag Carb 3 TBSP Neph Syenite

Cup #4 added 7 TBSP Mag Carb 4 TBSP Neph Syenite

Cup #5 added 6 TBSP Mag Carb 5 TBSP Neph Syenite

Cup #6 added 5 TBSP Mag Carb 6 TBSP Neph Syenite

Cup #7 added 4 TBSP Mag Carb 7 TBSP Neph Syenite

Cup #8 added 3 TBSP Mag Carb 8 TBSP Neph Syenite

Cup #9 added 2 TBSP Mag Carb 9 TBSP Neph Syenite

3.Then added enough water to mix in each cup to make like cream consisitency- approx. 1/2cup water

4.Dipped 2 sets of 9 tiles with two holes in them in these initial mixtures

5. Fired 1 set of two hole tiles to Cone 04

6. Fired 1 set of two holes tile to Cone 6

 

mixing cups and tiles

2 ingredients mixed with water, coated, and fired to (top) cone 04, (bottom)cone 6

7. mixed Ceramics Arts Daily Icy Blue Glaze cone 04

8. Added 1 heaping TBSP of ICY BLUE Glaze to cups 1-9

9. Fired 1 set of 1 hole tiles to cone 04

10. Fired 1 set of 1 hole tiles to cone 6

Conclusion= Loved the crazing and noticed size difference in the chunks as the cups numbers got larger. Ideally right now cup #5 with icy blue glaze added fired to cone 04 is right on the money for work. The higher fired tiles turned a dark brown color and the icy blue glaze faded out.