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New Zealand Halloysite

Alternate Names: New Zealand Kaolin, New Zealand PFC

OxideAnalysisFormula
TiO20.05%0.002
Al2O335.50%1.000
SiO250.40%2.410
Fe2O30.25%0.004
LOI13.80
Oxide Weight247.67
Formula Weight287.32
If this formula is not unified correctly please contact us.

New Zealand China Clays claim that this is the whitest clay in the world. The white primary clay deposits mined at Matauri Bay are derived from the alteration of acid volcanic rocks. The aluminosilicate feldspar minerals in the parent rhyolite have been broken down to their constituents by low temperature hydrothermal alteration and have then reconstituted as halloysite. Thus, while often called a kaolin, technically it is a halloysite.

The company has developed a unique beneficiation process (which includes filter pressing and thus the designation PFC or Premium Filter Cake) to ensure a high degree of purity. They claim 0.1% on a 240 mesh screen

This material is exported to many parts of the world. Small scale users have found it a little whiter burning than Grolleg Kaolin. It also supports translucency better. As a pure material, NZK is much less plastic than pure Grolleg (being barely plastic enough to wedge and roll into a slab, for example). However Grolleg requires about the same amount of bentonite (or VeeGum) compared to NZK to create a porcelain of the same plasticity. NZK responds especially well to VeeGum to create very plastic porcelains that still dry very well.


Fired color of a New Zealand based porcelain compared to other bodies

Fired color of a New Zealand based porcelain compared to other bodies

The whitest test bar here is a New-Zealand-kaolin-based cone 6 porcelain (employs VeeGum for plasticity). Immediately to the left of it are three North American-koalin-based bodies using standard bentonites. The bar to is right in a Grolleg based body that uses a standard bentonite rather than a white burning one. All are plastic.

Now that is a translucent porcelain!

Now that is a translucent porcelain!

These are two cone 6 transparent glazed porcelain mugs with a light bulb inside. On the left is the porcelainous Plainsman M370 (Laguna B-Mix 6 would have similar opacity). Right is a zero-porosity New Zealand kaolin based porcelain called Polar Ice (from Plainsmanclays.com also)! The secret to making a plastic porcelain this white and translucent is not just the NZ kaolin, but the use of a very expensive plasticizer, VeeGum T, to enable maximizing the feldspar to get the fired maturity.

Cone 6 porcelain marbled and thrown

Cone 6 porcelain marbled and thrown

These bowls were made by Tony Hansen using a mixture of white and stained New-Zealand-kaolin-based porcelain (Plainsman Polar Ice) fired at cone 6. The body is not only white, but very translucent.

Cone 6 translucent marbled bowl by Tony Hansen

Cone 6 translucent marbled bowl by Tony Hansen

A transparent glazed. It is a made from Plainsman Polar Ice in 2014 (a New Zealand kaolin based porcelain) and fired to cone 6 with G2926B clear glaze. 5% Mason 6306 teal blue stain was added to the clay, then this was wedged only a few times. The piece was thrown, then trimmed on the outside at the leather hard stage and sanded on the inside when dry.

Compare powder color of super white kaolins

Compare powder color of super white kaolins

These three materials also fire to a similar color. Grolleg is the most plastic, Dragonite the least.

Cast to only 1mm wall thickness? NZ Kaolin+VeeGum can.

Cast to only 1mm wall thickness? NZ Kaolin+VeeGum can.

This cast bowl (just out of the mold and dried) is 130mm in diameter and 85mm deep and yet the walls are only 1mm thick and it only weighs 89 gm! The slip was in the mold for only 1 minute. What slip? A New Zealand Halloysite based cone 6 translucent porcelain. This NZ material is fabulous for casting slips (it needs a little extra plasticizer also to give the body the strength to pull away from the mold surface as it shrinks).

Guess which mugs are made using an NZ kaolin?

Guess which mugs are made using an NZ kaolin?

The two mugs on the left: Traditional Grolleg porcelain using Nepheline and bentonite (fired to cone 10R). The right: Using New Zealand kaolin, Nepheline Syenite and VeeGum.

New Zealand Kaolin original container

New Zealand Kaolin original container

The original bag of this product in 2014.

Closeup of Halloysite particles

Closeup of Halloysite particles

Electron micrograph showing Dragonite Halloysite needle structure. For use in making porcelains, Halloysite has physical properties similar to a kaolin. However it tends to be less plastic, so bodies employing it need more bentonite or other plasticizer added. Compared to a typical kaolin it also has a higher fired shrinkage due to the nature of the way its particles densify during firing. However, Dragonite and New Zealand Halloysites have proven to be the whitest firing materials available, they make excellent porcelains.

Reduction and oxidation porcelains

Reduction and oxidation porcelains

Left: Cone 10R (reduction) Plainsman P700 porcelain (made using Grolleg and G200 Feldspar). Right: Plainsman Cone 6 Plainsman Polar Ice porcelain (made using New Zealand kaolin and Nepheline Syenite). Both are zero porosity. The Polar Ice is very translucent, the P700 much less. The blue coloration of the P700 is mostly a product of the suspended micro-bubbles in the feldspar clear glaze (G1947U). The cone 6 glaze is fritted and much more transparent, but it could be stained to match the blue. These are high quality combinations of glaze and body.

This is how much iron is in a box of the cleanest porcelain you can make!

This is how much iron is in a box of the cleanest porcelain you can make!

The recipe: 50% New Zealand kaolin, 21% G200 Feldspar, 25% silica and 3% VeeGum (for cone 10R). These are the cleanest materials available. Yet it contains 0.15% iron (mainly from the 0.25% in the New Zealand kaolin, the VeeGum chemistry is not known, I am assuming it contributes zero iron). A 50 lb a box of pugged would contain about 18,000 grams of dry clay (assuming 20% water). 0.15% of 18,000 is the 27 grams of iron you see here! This mug is a typical Grolleg-based porcelain using a standard raw bentonite. A box of it contains four times as much iron. Enough to fill that cup half full!

Out Bound Links

In Bound Links


By Tony Hansen

XML for Import into INSIGHT

<?xml version="1.0" encoding="UTF-8"?> <material name="New Zealand Halloysite" descrip="" searchkey="New Zealand Kaolin, New Zealand PFC" loi="0.00" casnumber=""> <oxides> <oxide symbol="TiO2" name="Titanium Dioxide, Titania" status="" percent="0.050" tolerance=""/> <oxide symbol="Al2O3" name="Aluminum Oxide, Alumina" status="" percent="35.500" tolerance=""/> <oxide symbol="SiO2" name="Silicon Dioxide, Silica" status="" percent="50.400" tolerance=""/> <oxide symbol="Fe2O3" name="Iron Oxide, Ferric Oxide" status="" percent="0.250" tolerance=""/> </oxides> <volatiles> <volatile symbol="LOI" name="Loss on Ignition" percent="13.800" tolerance=""/> </volatiles> </material>


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