|Monthly Tech-Tip |
The designation for a group recipes for body, glaze and engobe (by Tony Hansen), that potters can use to make low fire stoneware and fritware porcelain at 1100C (2000F) or cone 03.
Key phrases linking here: zero3 stoneware, zero3 fritware, zero3 - Learn more
The term "Zero3" was coined by Tony Hansen. It refers to recipes he developed at Plainsman Clays that enables a potter to create red-burning stoneware and blue-white porcelain at cone 03. The white version was later supplanted by the Zero4 porcelain, it matures to equal strength at cone 04, a temperature much more commonly fired by potters. The red version was succeeding by our L4170B recipe.
The secrets to why the system (group of recipes) functions well:
-The porcelain and red earthenware body recipes incorporate a sodium frit to make them vitreous (for the red body, only 5% is needed, 20% for the white).
-The glazes employ common Ferro frits (four of them), the rationale for their recipes and chemistries are meticulously explained.
-Three clear glaze recipes were initially given (L, K, H), having thermal expansions that span a broad range. They are shown side-by-side (with chemistry). Users can blend these to get a good fit. Then can further develop them in their insight-live.com accounts. More recently the G3879 recipe is showing great promise.
-The firing schedule employs a drop-and-hold to ensure cloud-free transparent results.
-The porcelain Zero3 body employs a blue stain to make it look like a cone 10R porcelain.
-The engobes are well explained and tested. The page explaining them is the first online coverage of how to develop an engobe and the importance of fitting it well to a specific body.
-The system is well tested using commercial underglazes (which show through the clear to produce brilliant effects). It is well represented in an image search on google.
-The development project is ongoing and much of it exists as a share from the Plainsman Clays account on insight-live.com. That means whenever a change or addition is made to the testing records, it updates online automatically.
The recipes use common ingredients in North America and enable the potter to mix his own body, glaze and engobe. If you live elsewhere consider making a 50:50 mix of ball clay and frit 3110 (equivalents to it should be available everywhere), then wedging that together with a terra cotta body available to you. A 10:1 mix would produce a body having 5% frit.
Want to learn more? It is code numbered L3924C, all the details along with information on the G2931K base glaze are available.
This porcelain mug put into kiln at 8:45am and I was drinking coffee from it at 12:15! How? One way to fast-fire is to fire a lot lower. This is Zero3 porcelain made using Dragonite Halloysite (not quite as white-burning as New Zealand Halloysite). It is the L2934C recipe. It was fired to cone 03 and glazed with G2931K clear glaze (which has fired crystal clear and flawless). I fired at 1200F/hr to 1950F, held it for 15 minutes, cooled at 999F/hr to 1850F and held it for 30 minutes, then dropped as fast as the kiln would do. Is this really porcelain? Yes. And it is super strong. The frit in the recipe is magic, making it vitrify quickly and completely.
This is an all-fritted version of G2931F Zero3 transparent glaze. I formulated this glaze by calculating what mix of frits must be employed to supply the same chemistry of the G2931F recipe. The mug is made from the Zero3 porcelain body (fired at cone 03) with this glaze. This glaze fits both the porcelain and the Zero3 terra cotta stoneware. The clarity, gloss, fit and durability of this glaze are outstanding.
Look at how translucent this is! I can fire one of these in three hours, cold-to-cold. I am casting them with molds made using the 3D-printing process. Anyone could do this. Incredibly exciting. And with the G3879 glaze it looks awesome, just like bone china. Notwithstanding this, the Zero3 recipe has to be altered for casting. Initially I have reduced the VeeGum to 1% but it is still casting too slow. And it is not shrinking enough to pull away from the mold well. I am considering strategies on how to increase drying shrinkage and am going to add more frit to take it down to cone 04.
Decorate ware with the underglazes at the leather hard stage, dry and bisque fire it and then dip-glaze in a transparent that you make yourself (and thus control). These mugs are fired at cone 03. All have the same transparent glaze (G2931K), all were decorated with the same underglazes. Notice how bright the colors are compared to middle or high temperature. On the left is a porous talc/stoneware blend (Plainsman L212), rear is a fritted Zero3 stoneware and right is Zero3 fritted porcelain. When mixed properly you can dip ware in this glaze and it covers evenly, does not drip and dries enough to handle in seconds! Follow the Zero3 firing schedule and you will have ware of amazing quality.
The mug on the left is high temperature Plainsman P700 (Grolleg porcelain). The other is Plainsman Zero3 fired at cone 03. Zero3 has a secret: Added frit which reduces the porosity of the terra cotta base (therefore increasing the density) dramatically. How? The frit melts easily at cone 03 and fills the interparticle space with glass, that glass bonds everything together securely as the piece cools. Although I do not have strength testing equipment right now, I would say that although the P700 mug likely has a harder surface, the Zero3 one is less brittle and more difficult to break.
Want to make this incredible porcelain and glaze yourself? Read on. The mug on the left is a cone 10R (2350F/1290C) porcelain (#6 Tile kaolin and Nepheline Syenite) with G1947U clear glaze. The other is a fritted cone 03 (1950F or 1065C) porcelain (NZ Kaolin, Ferro Frit 3110) with G2931K clear glaze. We call the body/glaze/firing system "Zero3" (google it or use the links here). The Zero3 porcelain is blue-white instead of grey, the glaze is crystal clear, underglaze colors are so much more vibrant. This Zero3 mug was fired in 3 hours (cold-to-cold). It fits glazes really well, it is very strong and much more translucent. How is this possible? The magic of the frit, it melts so much better than nepheline. It is the most expensive body you will ever make. But from it you may create the highest quality ware you have ever made using the most plastic body you have ever thrown! Follow the instructions carefully.
This bowl is 18cm (7") tall and weighs 1.8kg (4 lb). The marbling was achieved by wedging together white and colored Zero3 fritware porcelains, then thrown on the potters wheel and tooled at leather hard stage. The base is much thicker than the lip yet the degree of maturity appears homogeneous (despite a firing to cone 03 in less than 4 hours). I broke this with a hammer and with difficulty, it has the same kind of vitrified character as a high temperature porcelain.
Plainsman Zero3 Glaze L,K,H and Firing Schedule
Zero3 porcelain/stoneware, engobe, clear glaze and firing schedule
The designation for a group recipes for body, glaze and engobe (by Tony Hansen), that potters can use to make low fire stoneware and fritware porcelain
Slipware, in the UK, is terra cotta pieces decorated at leather hard with thixotropic high ball clay slips, then bisque fired and clear glazed with lead bilisicate.
L3685U - Cone 03 White Engobe Recipe
A white burning body with enough added frit to produce a cone 03 stoneware or white slip for use on the matching red Zero3 stoneware.
G3879 - Cone 04 Transparent Low-Expansion transparent glaze
A super transparent low fire base clear glaze created by reverse engineering a commercial product.
G2931H - Ulexite High Expansion Zero3 Clear Glaze
A cone 03-02 higher expansion fritted clear glaze developed from Worthington Clear.
L3924C - Zero3 Porcelain Experimental
G2931K - Low Fire Fritted Zero3 Transparent Glaze
A cone 03-02 clear medium-expansio glaze developed from Worthington Clear.
|By Tony Hansen|
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