All Glossary

Zero4

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

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Details

Zero4 porcelain (code number L3924J ) is a fritware concept-body designed at Plainsman Clays during 2022 (it employs Ferro Frit 3110 as the flux instead of the feldspar used in typical porcelains, to get the recipe and more technical information and pictures click that code number in the last sentence or google "L3924J recipe"). Zero4 reaches zero porosity at cone 04 and looks, feels and performs like a fine porcelain. Because it vitrifies so early bisque temperature is best around 1450F.

The recipe is public so you can mix it for yourself. Zero4 is for potters who like to experiment with mixing their own clays, it involves weighing out the ingredients, mixing it as a slurry using a high-speed propeller mixer and then dewatering it on a plaster batt (actually, blender mixing is better, that will break down agglomerates). No clay body manufacturer that we know of sells anything that is even close to this (because it would be so difficult to make), so if you take the trouble to make it you are creating very unique ware.

This is a follow-up to the Zero3 recipe, it is more vitreous and is targeted at working with standard low-temperature commercial glazes and underglazes. Zero4 porcelain has a companion glaze recipe based on G1916Q that promises super gloss and transparency. We are still assessing its long term resistance to leaching.

Want the recipe and to learn more? Zero4 is code numbered L3924J, all the details along with information on the G1916Q3 base glaze are available. Could it go lower? Yes - with more frit or a lower melting one. Could it go 200-300F lower? Yes, there are bismuth frits that can do that (but at an obvious cost).

Related Information

Zero4 fritware mugs fired at cone 04

To a potter, it may seem impossible that porcelain can be this dense and strong at such a low temperate. To achieve its very high plasticity and fired density this has 18% total shrinkage. Using this Zero4 fritware porcelain, very thin-walled pieces can be thrown. The frit also produces a higher expansion body that fits any low-temperature glaze we have tried. This is G1916QL3 ultra gloss clear glaze on Amaco Velvet underglazes. The low temperature has another benefit: Very sharp edges on painted underglaze designs. Zero4 replaces our old Zero3 porcelain.

Zero4 frit ware broken with cross section close-up

The body is highly plastic and can be thrown very thin. At cone 04 this thin-walled mug did not warp even though it fired to a near-glasslike cross-section. The density and strength are amazing, it took about 30 hits with a hammer to break it, hitting it as hard as I dared without risking being cut with the handle I was holding it with. The whiter flecks are agglomerates of New Zealand kaolin (because of improper mixing of the slurry), later batches we made were much better.

Zero4 porcelain mugs using New Zealand and Grolleg Kaolins

Both of these Zero4 fritware porcelain mugs were bisque fired at 1450F and glaze fired at cone 04. The Grolleg version of the porcelain is burning a much pinker color (both the bare body and under our G1916Q3 glaze). In typical feldspar porcelains the color difference between these two kaolins is not nearly so much but here the extra glass development is likely amplifying the presence of even just a little more iron oxide.

Here is what happens when Zero4 porcelain gets lit up

Wall thickness is 2.5mm. Fired at cone 04. At cone 02 it is much more translucent than this and still stable.

Zero4 translucency at cone 04 and 02

Wall thickness is about 2.5mm. Although not as clear in the photo, at cone 02 it transmits light much better, the most translucent of any porcelain we have seen. The grainy surface on the piece on the left is because I did not properly mix the slip to remove all the agglomerates of New Zealand kaolin.

Blue and orange stains in Zero4 porcelain fired at cone 06

Mason 6315 zirconium vanadium blue 1-10% and Mason 6028 Orange 1-10%. In both cases, 6% appears to achieve maximum color (colors will be even brighter when fired to the full cone 04). Both of these are listed as candidates for staining bodies on the reference guide at masoncolor.com. Fritware bodies like this have much more glass development during firing than porcelains and thus amplify stain colors better. It is typical to only use body stains for this type of experiment, but because the firing temperature is so low and firings can be done quickly it is likely that more stains will work that in typical cone 6 or 10 porcelains. This is potentially a good process for jewelry making. Photo courtesy of Karen Ho Fatt Lee.

This is what Zero4 porcelain does when I smash a piece with a hammer

This has happened on multiple occasions, the handle survives holding separate pieces of the remaining mug. The porcelain seems to have an elasticity that enables it to withstand impacts.

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Zero4 mugs ready for drying

Cone 10R porcelain (left) vs cone 03 porcelain (right)

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