The only way to be sure it's safe, is to send the pizza to a certified lab for testing.
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Matt OzMember Since 16 Dec 2011
Offline Last Active Sep 04 2016 09:54 AM
Some recipes here http://mozporcelainr...s.blogspot.com/
My work is mainly created using slabs and press molds, along with a few freehand sculptures.
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Posted by Matt Oz on 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 difference 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 seem close enough.
Cone 6 Porcelain
20 Silica 325 mesh
20 G-200 feldspar
1 Veegum T
2 Frit 3134
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
Fe2O3_ 0.70% 2nd highest
TiO2___0.37% 2nd highest
Fe2O3_ 0.79% Highest
Fe2O3_ 0.50% 2nd lowest
Posted by Matt Oz on 25 February 2015 - 03:35 PM
Here is a post from an AMACO engineer on this subject.
and here is the thread it is from....Anyone Use Amaco Potters Choice Saturation Metallic Or Gold?
Palladium and Saturation Gold Users,
My name is Steve Lampron and I am the ceramic engineer here at AMACO. I want to give some simple tips about firing the Palladium and Saturation Gold glazes.
Palladium: This is what I call a float glaze. This means that in order to get the shiny silver look you need to actually allow the supersaturated metallic particles to float to the surface and form the skin. There is no trick to this other than to make sure you put a good thick layer of glaze on the piece. This is true of many glazes (commercial and made at home) which need a good thickness of glaze in order to make the surface. If you do not put enough glaze on, you will not have enough excess material to float and the glaze will look totally wrong. In the case of Palladium, it will be a fairly ugly green color. We fired this glaze on all of our clay bodies at both cone 5 and cone 6 with great results. I have a caution; this glaze can be very fluid and run so make efforts to allow for this. When you first try glazes you need to run test tiles (pieces) that are fired vrtically where you vary the thickness from what you think is too thin to what you think is too thick. This will show you where to go to get the look you want, it will also show you what it looks like when it is wrong. You will then know what went wrong when you get a pot that looks wrong. This glaze will be fine at cone 5 or 6 and requires no soak (it will make it run more). A medium / 8 hour firing is good. Cool normally. I see that a few people have gotten some blisters on pots that are fully glazed. This has happened on some clay bodies I found out after releasing it. It never seems to happen on poecelain bodies and these will also give the best surface. Please try your pots again on porcelain.
Saturation Gold: This is also a float glaze so thickness is important as well. The glaze doesn't turn out a bright shiny gold like gold lusters or the old leaded cone 05 golds. It turns out a dark kind of wrinkled bronze gold. It is not an easy glaze to get to look smooth and perfect. The suggestion that applying it over another glossy mid-range glaze is something that I find also helps the surface. The plain fact of the matter is that this type of glaze is difficult to use and requires alot of trial work. The kiln Gods probably didn't want this type of glaze to be made. It can be beautiful when perfected but it is not as simple to perfect as a pretty little matte white glaze.
I can't stress enough how important it is for all potters (especially new ones) to test glazes well before making pots. I know the desire to just make a pot but this method will only lead to disappointment and bad pots. Let me know if this helps or if I can address any other concerns you have.
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Posted by Matt Oz on 17 January 2015 - 09:45 PM
Tyler Miller explains this better than I've seen in a while...and that appreciation is coming from someone who would still be an undergraduate if he had to take one more chemistry class. Thanks Tyler!
On a less serious note, when I first read the topic question I was reminded of an old joke:
Two hydrogen atoms walk into a bar...
One says, "I've lost my electron".
The other responds, "Are you sure?"
The first replies, "Yes. I'm positive!"
When two elements love each other very much, they come together to form a compound.
Sorry, I'm not helping.
Posted by Matt Oz on 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.
Posted by Matt Oz on 13 December 2014 - 04:52 PM
The black clay I used was a porcelain with black mason stain. These were a single fire, but I have used it on bisque ware and there are still bubbles if it is thick.
I have a slow warm up at the beginning but after that its just
300 degF/hr to 1980
110 degF/hr to 2180 or whatever bends cone 6
No slow cool or hold.
Here is one more of tile one through a magnifying glass, shows ever-smaller bubbles. Now I have to go fire up the Electron microscope, where did I put that thing?
Posted by Matt Oz on 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.
Tile one closer
The glaze is:
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.