Glazing

The surface of fired pottery is generally porous and readily absorbs moisture. To conceal outside imperfections, decorate the surface, and make the pottery more or less impervious to water and other liquids, many ceramic objects are glazed, that is, coated with a thin layer of glaze (Tite 2004). The nature of glaze and the glazing process are discussed in Chapter 3. 

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Borax is used in the production of pyrex glass, ceramics, as a flux in soldering and welding, and in laundering to impart a glaze to linen. 

Tbe pbenol should be weighed out carefully on a piece of glazed paper on the balance pan. If spilt crystals of phenol are allowed to remain on the balance pans, the latter may become corroded. If phenol is allowed to come in contact with the hands, it should be washed off without delay,... 

Crystals of uranium nitrate are triboluminescent. Uranium salts have also been used for producing yellow "vaseline" glass and glazes. Uranium and its compounds are highly toxic, both from a chemical and radiological standpoint. 

Chinaware Chinaware glazes Chinawood oil Chinese blue... 

Structural glazing Structural promoters Structural RIM Structural RIM (S-RIM)... 

Acryhc modifiers for cement impact strength and adhesion to substrates are discussed in reference 211. Both water-soluble acryhc and acryhc emulsion polymers are used in the ceramic industry as temporary binders, deflocculants, and additive components in ceramic bodies and glazes (212) (see Ceramcs). 

Sheet can be produced by melt extmsion, but in this case a three-roll stack of quenching roUs is generally used (Fig. 2). More than three roUs may be used where necessary. The roUs may be mounted vertically or horizontally. The web is extmded through a slot die in a thickness close to the desired final thickness. The die is in very close proximity to the first chill roU or chill-roll nip. The web may be cast horizontally directly onto the upper chill roU of the stack as shown (Fig. 2), or it may be extmded into the first nip directly. The roUs quench the sheet and provide the surface polish desired. In some applications, matte or embossed roUs maybe used to impart special surface characteristics for certain functions. Where the utmost in optical (glazing) quality is desired the trend has been to mount the roU stack horizontally. The hot melt is then extmded vertically down into the first nip. This avoids problems associated with sag of a horizontal hot melt no matter how short the distance between die and quench. 

Microscopic examination of cross sections through the paint layers gives definite information regarding the paint-layer sequence in the area from which the sample was taken (31,66). This information illustrates the artist s use of underlayers and glazes, superposition of compositional elements, and changes in composition. 

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