The Basic Reference Guide To Clay

Characteristics

High Fire Stonware Clay (Cone 10)

Earthen- colored stoneware clays produce durable ware and most will react favorably to the manipulation of air, gas and smoke in reduction firing. These clays have good plasticity and will perform well in both wheel throwing and hand building methods.

High Fire White Stoneware Clays (Cone 10)

High fire white stoneware clays also have good plasticity and contain a small amount of sand to increase their strength and workability, making them slightly open when fired. These clays have become very popular because of the clean canvas they provide for a myriad of glaze colors. Some iron speckling can occur but for the most part, glaze colors are not affected.

Midrange Stoneware Clays (Cone 4-6)

Midrange stoneware clays are similar to cone 10 clays in their workability and represent potential savings in lower firing costs. The lower firing temperature and oxidation atmosphere allow for the use of a large palette of ceramic stains and cause less warping of the ware.

Porcelain Clay (Cone 6-11)

Porcelains are most commonly known for their whiteness and for having some degree of translucency. They are pure and vitreous which gives them their inherent glaze fit quality and unparalleled hardness and durability. 

Low Fire Earthenware Clay (Cone 06-04)

Low fire clay tends to be either reddish or white in color. These clays tend to be more porous, making them ideal clays for planters. Glazing is required to create a waterproof surface. When fired, these clays are non-vitreous and have low shrinkage. Low fire dinnerware does not take extremely hot temperatures well, and repeated exposure to such temperatures can result in cracking and crazing. 

Paper Clays

Paper Clay is a combination of paper pulp and clay that has the benefit of strength that aids in the safe transport of work and reduces breakage of larger pieces. Water transporting fibers make slip joined dry-to-dry additions successful and also aid to reduce warping and cracking of tiles, slabs and during force drying. We offer Miller/Laguna Max's Cone 5 Paper Clay (Cone 04-10), BMix w/ Grog Paper Clay (Cone 04-10), and Bob's Tile & Sculpture Clay (Cone 04-6). Paper clays are made in small batches and can be special ordered through The Ceramic Shop. 

Non Firing Clay

These Clays are designed not to be put in the kiln and are intended for sculpture or decoration, not dinnerware. Non firing clay comes in self hardening (or air dry) that dry to be super stiff without a kiln firing. Modeling Clays keep their softness and can be reused over and over again for mold making or kids projects. Recommended Self Hardening Clays: Miller/Laguna: Wed, Standard Clay 910, Amaco: Stonex. Modeling Clays: Amaco Artone Venus, Modeling Clay, Kids Modeling Clay: Amaco Plasticlay, Super Dough, Cloudclay, Mudmagic 

Uses

Dinnerware/ Tableware 

Functional ware is considered objects like bowls or mugs that will be holding foods or liquids. There are a wide variety of different types of clays ranging from dark stoneware to smooth white porcelain or slightly grogged textured clays that are suitable as long as they have a low water absorption rate. For stoneware clays look for a claybody with less than 3% absorbtion and for porcelain look for less than 1%.

Recommended clays for Cone 10: Miller/Laguna Clays BMix10, 750, 900.  Standard Clays: 153, 259, 306, 181, 182. For Cone 5-6: Miller/Laguna Clays Bmix5, 40, 45, 50, 55, 60, 65. Standard Clays: 112, 240, 266, 553, 563, 153, 259, 306, 181, 182.

Ovenware 

Many stoneware clays will work well for ovenware, but clays that can handle the thermal shock of low to high temperatures work best. Cone 5 stonewares tend to be less susceptible to thermal shock but all ovenware made of stoneware should be heated and cooled gradually. Selecting a glaze that fits well and can also withstand the heating and cooling changes is necessary and may take some testing to figure out what works best.

Recommended clays for Cone 10 include: Miller/Laguna 750, 900. Standard Clays: 153, 259. Cone 5-6: Miller/Laguna Clays 60, 70, 45. Standard Clays 112, 153, 259.

Floor & Outdoor Tile 

Tiles should be made from a strong, durable clay to withstand wear and tear and changes in temperature. Commercial producers employ special production techniques to increase the durability and provide lower shrinkage. You'll want to select a tile with grog for floor tiles and clays with low absorption rates (2% or less) for outdoor tiles. Glazing outdoor tiles and using a cover sealant will help protect your tiles from the thermal shock of changing weather.

Recommended clays for floor tile include Cone 10: Miller/Laguna Clays 900, 900. Standard Clays 108. Cone 5-6: Laguna/Miller 45, 60.  Standard Clays 108, 420, 547. Low Fire Cone 06-04: Laguna/ Miller Clays 26, Standard Clays 104. For outdoor tiles use 900, 80, 90, 65, 66 547, or 26. 

Sculpture Clays 

Sculpture claybodies contain significant amounts of sand and grog in various mesh sizes and are formulated for a low rate of shrinkage. These clays are designed to accommodate large handbuilt, wheel thrown or sculpted projects. Recommended clays for Cone 10 include: Miller/Laguna 950, 900. Standard Clays 108. Cone 5-6: Miller/Laguna Clays 45, 66, 75. Standard Clays: 547, 420, 239. Low Fire Cone 06-04: Miller/Laguna 10G, 20G, 26, Standard Clays 104, 105G, 239.

Atmospheric Clays

Atmospheric clays including raku, woodfire, salt fire, and reduction must be durable to withstand the thermal shock or changing temperatures. They should also have good flashing properties if used for woodfiring, salt firing, or reduction. Recommended clays for Cone 10 include: Miller/Laguna Bmix10. Standard Clays: 437, 621, 508, 119, 153, 507. Highwater Clays: Helios, Loafers Glory, Craggy Crunch, Phoenix. For raku use Miller/Laguna 200, 250, or Standard Clay 239