Low-fire clay

Low-fire clay is available in a variety of colors and can be used successfully for making small decorative items. It will harden when baked in a regular kitchen oven at a low temperature, but it cannot be glazed. Various brands of self-hardening clay are available. It will harden in air, drying with a permanent finish, and it is available in a variety of colors suitable for small decorative objects such as beads and jewelry. 

Wacker-Chemie (1982) Silicone Impregnation of Low Fired Clay Products, Wacker-Chemie GmbH, Munich. 

Low-fired clays differ widely as to their hygroscopic capacity and the temperature at which they release the moisture thus absorbed. At the same time, the expulsion of this moisture requires considerable time. Therefore, it is not sufficient simply to keep the crucibles in a warm place, but they should be finally maintained for at least several days at a higher temperature, say 150 C., before being placed in the furnace. In Europe the crucibles on being taken from this kiln are sometimes covered with a waterproof coat, such as tar or pitch dissolved in turpentine. 

Chem. Descrip. Methyl slllconate In water Uses Water repellent, hydrophobic sealer for low-fired clay prods, (roof tiles, facing bricks, flower pots), aerated concrete, post-treatment of gypsum boards, light fillers such as perlite, vermicullte, and aerated concrete granules additive to whitewash and water-based paints, primer for emulsion paints and plasters Features Water-based VOC compliant Properties Colorless to yel. sp.gr. 1.29 pH = 13 42% solids Environmental Environmentally friendly... 

Matziaris K, Stefanidou M, Karagiannis G (2011) Impregnation and superhydrophobicity of coated porous low-fired clay building materials. Prog Org Coat 72( 1-2) 181-192. doi 10.1016/j. porgcoat.2011.03.012... 

Tne insulating firebrick is a class of brick that consists of a highly porous fire clay or kaolin. Such bricks are light in weight (about one-half to one-sixth of the weight of fireclay), low in thermal conductivity, and yet sufficiently resistant to temperature to be used successbilly on... 

Higb-duty fire clay SiOa, 54% AI263, 40% 134 3125 Acid Fair 18 Moderate Fair Fair Good Good at low temperatures... 

As the fuel is consumed, one places a metal container over the fire to produce a reduction atmosphere . This is one way to insure that the high black luster will occur on the surface of the pot. While the clay body can contain a high amount of iron oxide, like the clay body used in low-fire earthenware, covering the pots during the firing will cause some coloration irregardless of the amount of iron oxide in the clay body. Potters tend to use whatever metal container is easily available. Salvaged car hoods or metal wash tubs are common. Prior to the introduction of manufactured materials like this, one would cover the fire with a layer of dry dirt or soil. 

Just about any type of low or medium fire clay body can be used. The critical element is maintaining the heat of the firing kiln at or below Cone 6 (about 2174°F). At higher temperatures,the glass strands will melt and flow out of the clay, leaving voids and resulting in a very weak panel. 

Basic raw material are low-grade, coloured-firing clays. Non-plastic substances are added in the form of sand, slag, fly-ash, etc. The proportions added are given by the required forming properties and behaviour on firing. 

Flint clays do not slake in water into a plastic mass, and exhibit low firing shrinkage. 

The volumes of the clay and waste solution are nearly additive. Therefore, the amount of clay necessary to form an acceptable product will determine the volume increase for the process. Fired clays appear to give the smallest volume increase (as low as 20% for the standard waste solution). 

The minimum amount of clay necessary to solidify the standard waste solution completely was measured for several clays. A solid product is defined as one that can be filtered at 100 psi using a pressure filter, with no resulting liquid. The results of these measurements for solidification of the standard waste solution are given in Table X. These results indicate that less volume is necessary if kaolin is used. Reactions with fired clays have resulted in volume increases as low as 20% (10). 

Industrial fine stoneware (for laboratory apparatus, insulators) is manufactured from low quartz clays which fire to a light color, producing a porcelain-like article. 

Bright yellow-white Mid-range clays and low-fire stonewares mature. High... 

NAA study of approximately 170 sherds from the site was undertaken to answer this question. This totally included 117 sherds and three fired clay samples from Pinson Mounds, 39 sherds from nearby contemporary sites, five samples of clay sources in the area, and six sherds from a Hopewell site in Georgia. Nineteen of the sherds from Pinson appeared to be nonlocal in style and temper. The research reactor at the University of Missouri was used to irradiate the samples and instruments measured the abundance of 33 elements in ppm in the pottery. Statistical analysis of the data from the NAA study was then undertaken. The authors of this study, Mainfort and colleagues, removed a number of samples with unusually high or low data values (known as outliers) from their study, arguing that these outliers can cause samples to appear more similar. 

Fire clay Low heat duty High heat duty Mullite, glass, quartz Mullite, glass Up to 1500 Kiln linings Crucibles... 

To obtain good conversion by reaction (4) even with an excess of steam It is necessary to use an active catalyst in order to operate at a temperature lower than 1000° C. Nickel catalysts, promoted with alumina or thoria and supported on fire clay, magnesium oxide, or brick, are very suitable for the process, giving essentially equilibrium conversion at low rates of gas flow through the converter. At increasing rates of flow the increase in unconverted methane is practically linear with the increase in space velocity. ... 

The crucibles were made of fire-clay, and could stand five or six charges each, each charge being 48 5 lbs. of impure antimony. To each charge were added 13 to 17 lbs. of flux, which was a mixture of sulphate and carbonate of soda, with a little salt and pure oxidised antimony ores. The fusion lasted six hours, with a consumption of 450 to 550 lbs. of coal. A low red heat is necessary. 

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