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Matt Oz

Member Since 16 Dec 2011
Offline Last Active Nov 24 2015 08:00 PM

Topics I've Started

Comparing Translucency Of Various Kaolins In A Cone 6 Porcelain Body.

09 June 2015 - 01:15 PM

I like to do a lot of experiments formulating translucent cone 6 porcelain bodies and wanted to show the differences in translucency of kaolins.


I use this recipe with Grolleg and did not compensate for more refractory kaolin's when mixing up test batches, but from doing various tests in the past these results seemed close enough to show the differences.


Cone 6 Porcelain

50 Kaolin

20 Silica 325 mesh

20 G-200 feldspar

4 Talc

1 Veegum T

5 Wollastonite


2 Frit 3134

2 Bentonite



For the test tiles I give the percentage of titanium and iron that the kaolins contain, referencing digitalfire.com, with each sample because:

Titanium (TiO2) affects translucency and color.

Iron (Fe2O3) affects color, and less so translucency.


Tiles are approximately 3/32" thick (2.4 mm), fired in an electric kiln.


Back lit with led bulb.



Left to right:

New Zealand Halloysite (kaolin)

TiO2___0.05%  2nd lowest

Fe2O3_ 0.25%  Lowest



TiO2___0.03%  Lowest

Fe2O3_ 0.70%  2nd highest



TiO2___0.37%  2nd highest

Fe2O3_ 0.79%  Highest


#6 Tile

TiO2___1.40%  Highest

Fe2O3_ 0.50%  2nd lowest

Translucent Porcelain Hidden Pattern Experiment.

20 December 2014 - 06:50 PM

I experimented with an easy way to create a simple pattern with colored porcelain that also creates a more complex one that only emerges when backlit, I used coils of porcelain colored with Mason stains and the opacifier Zircopax.

Haven’t done anything with it yet, other than make test tiles, and I’m sure there have been lots of creative techniques used out there to do similar.


I'm using a glassy porcelain that melts and slumps to much to use for most projects, if anybody tries this you should get good results with one of New Zealand kaolin based porcelains.


Praseodymium stain for yellow.

Wedgewood for blue.

Zircopax for white.


Test tiles are about 3/32" thick roughly an inch wide

The photos are of a tile lit from the front, then backlit with a led bulb.



I twisted two coils together, one with a small amount of blue stain the other uncolored porcelain, then Inlaid them into a slab of lighter blue making a simple twist pattern, when lit from behind a more complex pattern appears.




Here is a pale blue and pale yellow twisted, where the two colors overlap it creates green when lit, doesn’t stand out much though.



This one is a white coil twisted with a uncolored porcelain coil then inlaid in white, so you can only see half the pattern when not backlit.


Hope you found these interesting.

Bubble Glaze Experiment With Close Ups.

11 December 2014 - 03:08 PM

A while ago I did some experiments with a cone 6 clear in a electric kiln that has lots of tiny bubbles in it when applied thicker, I made some small tiles (about 1 1/8" square) out of black clay so the bubbles would have good contrast and because they're fired horizontal I got a nice even spread of bubbles.

Some tests have additions of Mason stain.


The first tile has white clay inlaid in the black clay with small pieces of a glassy porcelain I have that were placed on top of the glaze prior to firing.

Tile three has 1% Mazerine stain added to the clear with a streak of white glaze on top and a ball of porcelain.

The last one is 4% Praseodymium with porcelain additions.


Close ups:


Tile one



Tile one closer



Tile three



The glaze is:


25 3134

15 Custer

20 Kaolin

20 Silica

20 Wollastonite


Not the most compatible of glazes but bubbly. I don't remember exactly how thick the clear was but at least 4 coats and if applied too thick the glaze becomes too cloudy.

I haven’t experimented with this enough to know if it's useful or practical to do it this way, but found it interesting.