CLAY SEWER PIPE MANUFACTURE.—IV. THE INFLUENCE OF DIFFERENT SALT GLAZING TEMPERATURES UPON THE COLOR AND GLOSS OF GLAZES OBTAINED ON CLAYS WITH VARYING SILICA,ALUMINA, AND IRON OXIDE CONTENTS1

Object .—A study was made of the effects of different salt glazing temperatures upon the color and brightness of salt glazes produced upon clays with varying silica, alumina, and iron oxide contents. Results .—In tests conducted in commercial kilns operating under normal conditions, it was found that increasing the salt glazing temperatures has a tendency to produce duller and darker glazes on clays containing iron oxide. The brightness of the glazes produced may be approximately represented by the following formula: -1.00×₁+ 0.376×₂ - (1.885 + 0.385(1.01253)^(T-1110))×₃= 100G ×₁, ×₂ and ×₃ represent the percentages of silica, alumina and iron oxide, respectively. T is the salt glazing temperature in °C. When G was greater than 0, the glazes were bright; when between -0.1337 and 0 they were semi matt; and when less than -0.1337 they were matt. The color obtained may be approximately represented by the following formula: 10.3x₁ - 2.65x₂+ (14.6 + 54.1 (1.0066)^(T-1110))x₃= 100°C When C was between 0 and 2, white to tan glazes were produced; when between 2 and 3.5, light brown glazes were obtained; when between 3.5 and 4.75, brown glazes were produced; when between 4.75 and 8.2, mahogany colors were obtained; and when above 8.2, dark brown to black glazes were produced. Clays containing a high iron oxide content should be salt glazed at low temperatures while clays containing a low iron oxide content should be glazed at high temperatures to produce the best glazes. Decreasing the iron oxide and alumina contents will improve the brightness of the salt glazes. High alumina clays will produce darker colors than high silica clays with the same percentage of iron oxide.     

MOISTURE EXPANSION OF GLAZES AND OTHER CERAMIC FINISHES1

Research for ascertaining why some glazes are more resistant to “moisture crazing” than others revealed the fact that certain glazes expand, because of the action of water, similarly to some of the ceramic bodies t o which they are applied. Although a control of this type of expansion is very important in fitting glazes to bodies, it has not been previously considered. Its importance should be evident at once when it is considered that a large “moisture expansion” in a glaze or other finish is in many cases an indication that the glaze will not be so liable to craze when the ceramic ware or material on which it is used is exposed to moisture. This follows since the glaze and the body on which it goes and which is ordinarily very susceptible to this kind of expansion will then increase in size simultaneously and more nearly at the same rate. Such conditions lessen the tendency of the body expansion to cause tensile stresses in the glaze. In this investigation specimens of various finishes were subjected to steam at 150 pounds per square inch for an hour because it was known that this treatment of such materials produces effects similar to those caused by long exposure to weather. This artificial weathering treatment caused in lustrous glazes an average expansion of 0.004%, in mat glazes 0.011%, in vitreous slip finishes 0.005%, and in porous slip finishes 0.033%. The moisture expansion of one of the mat glazes was 30% of the average obtained for a ceramic body having an absorption of approximately 12%. This proclivity of ceramic finishes to expand by the absorption of moisture can be controlled in their manufacture.     

A STUDY OF THE CONSISTENCIES OF RAW TERRA COTTA GLAZES1

For measuring consistencies of glazes, a method was used based on the conception of glazes as plastic materials. A normal glaze thinned during the entire period of testing, being attended by a large decrease in yield value and a moderate increase in mobility. Use of an aged clay slip as a source of clay did not change the plastic properties or aging characteristics of the glaze. Heating a freshly milled glaze resulted in a consistency comparable with that developed by aging a normal glaze for a month. Water solubilities of glaze materials were determined as well as character and concentrations of soluble salts in mill liquors and P_H values of mill liquors. Solution of salts was progressive over a period of time and increasing alkalinity was probably the cause of spontaneous thinning. Gum arabic in proper amount was found to stabilize glaze consistency satisfactorily. Effects of acid, alkali, and water additions to gum-bearing and gumless glazes were studied.     

INTERFEROMETER MEASUREMENTS OF THE THERMAL DILATATION OF GLAZED WARE1

The network of fine cracks often seen in the surface of glazed products not only mars the surface but shortens the life and lowers the price of the ware. Since the relative expansivity of the glaze and body is a very important factor in controlling this condition reliable measurements of both are of the utmost importance. Until recently the difficulty has been that the expansivity of the glaze has been measured on specimens of the material melted to glass and drawn into rods or cast in molds of sufficient length. Owing to the difference between this treatment and that received by the material when spread on the ware, it was realized that these methods might lead to unavoidable errors. By the interference method, specimens 0.2 mm. in length can be measured with sufficient accuracy. Therefore in measuring glazes the samples may be taken directly from the finished ware. In this paper the thermal expansion of glaze materials prepared in the form of drawn glass or cast rods is compared with that of the same material taken from the finished ware. From the measurements, the expected divergence is found to be as much as 20% in the case of drawn glass specimens, and 10% for cast specimens.     

素烧坯改素坯施釉用色釉的配制

介绍了素烧坯改素坯施釉用色釉的配制。用配制的色釉可直接施于素坯表面,而不需要在素烧后施釉,使成坯与施釉连续操作,大幅度缩短生产周期,而且形成的釉层也不会出现釉裂和剥釉缺陷。     

THE REQUISITE CONSISTENCY FOR A CASTING SLIP1

Producing desirable flowing quality in a slip is proposed as a means of controlling its casting quality. A conception of plastic flow as a property incapable of being measured in terms of an absolute unit such as may be applied to viscosity measurement is presented and a simple gravity flow tube consistometer of suitable dimensions for obtaining comparative tests upon casting slips or upon similar suspensions is described. Only sufficient data are presented to aid in explaining or describing general principles or conceptions, to suggest means of obtaining desirable plastic flow and to show what the consistency of a vitreous sanitary ware casting slip now in use actually is. Stiffness, yield value, and starting pressure are regarded as the elements making up plastic flowing quality and it is necessary to take all three of these factors into account in order to specify the kind of flow obtained. The consistency of a casting slip which will produce good solid cast ware, described in terms of the test apparatus used in connection with this work, may be stated as follows: stiffness equals 60 cm. per cc. per sec.; yield value equals 20 cm.; plasticity ratio equals 2.5. Reference has also been made to the application of these Same principles to the control of glaze slips and to the testing of clays to determine their suitability for use in any process involving their plastic working properties     

明代早期祭红釉显微结构与工艺的研究

收集了明代早期 (永乐、宣德、成化 )不同年代的祭红釉瓷残片。用扫描电镜、透射电镜、能谱仪、电子衍射、荧光X射线光谱分析、光学显微镜等系统地研究了它们的显微结构 ,用体视显微镜、分光光度计等观察、测定了它们的呈色状况 ,详细探讨了明代祭红釉之间的差别 ,分析了它们的生产工艺与化学组成、显微结构之间的关系。     

闪光釉闪光机理的研究

闪光釉的特征是对入射光有金属镜面般的反向，研究表明，这种反射是由釉中心（200）晶面平行于釉面的的CeO2晶粒造成的，晶粒的取向程度越高反射越强，闪光釉只有施在相应的底釉上才具有闪光效果。     

SOME LEADLESS BOROSILICATE GLAZES CONTAINING NICKEL OXIDE1

The literature pertaining to the use of nickel oxide in all types of glazes is briefly reviewed. A study of the effect of the various glaze constituents on the color and other properties of some leadless borosilicate glazes containing nickel oxide as a colorant is given. Nickel oxide has not proved useful in glossy non-opaque glazes. It is not recommended for use where a deep (dark) color is desired but can be made to produce very pretty opaque glazes, light tan in color and of a semimat character.     

Color Fading of Underglaze Decalcomania

A study was made of some possible causes of color fading of underglaze decalcomania used in the commercial production of semivitreous dinnerware, While the quality of the decalcomania employed is of primary importance, ware losses due to color fading can be minimized by careful control of glost firing procedures, adjustment of glaze composition, and proper fritting practice. Cone 2 dinnerware glazes identical in chemical composition but different in constituency were found to have widely different characteristics toward underglaze colors. Best results were obtained when lead oxide was fritted and 10% or more whiting was left unfritted and added as a mill addition. Low-melting frits did not produce so good results as did the more refractory frits. Strontia, as a lead replacement, was effective in reducing color fading. Barium oxide also showed characteristics favorable to underglaze colors, but tin oxide, zinc oxide, and magnesia, even in small amounts, were decidedly harmful to most colors. When alumina and silica were varied and other oxides were kept constant, increases in alumina were decidedly unfavorable to most colors, resulting in extreme fading at the higher alumina contents. The effect of raising the silica content was generally favorable. For best results, glazes should be compounded to prevent the formation of low-temperature melts. Adjustment of glaze composition to increase viscosity and lower surface tension of the molten glaze is suggested as a method of minimizing glaze attack on color.     

Jun ware glazes: Chemistry,nanostructure and optical properties

A set of the Classic and official Jun ware shards found at various kilns at Yuzhou (Henan) are analyzed. The blue color and milky appearance of the glazes subject of intense debate as being due to either the glaze nanostructure or chemistry. The presence of submillimetre areas showing different color and opacity gives to the glazes a three dimensional cloudy sky appearance. Nanostructure and chemistry of the glazes, oxidation state of iron and nature of the copper nanoprecipitates are studied at a submillimetre level. Images of the glaze nanostructures are obtained using a Focus Ion Beam and Scanning Electron Microscope with nanometric resolution. The size and volume fraction of the nanostructures determined by image treatment are related to the chemical composition of the glazes. Differences between kiln productions are found and the origin of the color and opacity of the glazes discussed in terms of the chemistry and nanostructure.     

SOME EFFECTS OF THERMAL SHOCK IN CAUSING CRAZING OF GLAZED CERAMIC WARE1

The characteristics of glazes are too frequently regarded as the only important factor governing the resistance of glazed ware to thermal shock crazing. In this investigation it was found that thermal shock crazing was caused, in some cases, by craze-like cracks which developed in the bodies. The importance of selecting suitable bodies, as a means of controlling crazing, became evident at once when it was found that bodies with a high resistance to thermal shock were not so liable to craze when glazed and subjected to sudden temperature changes as those with a low resistance to thermal shock. In general, glazed ware on which the glazes are under fairly high compression are more resistant to thermal shock crazing than those on which the glaze is under either low compression or tension. Glazed ware which is susceptible to thermal shock crazing may be resistant to moisture crazing and vice versa.     

METAL MARKING OF WHITEWARE GLAZES AS INFLUENCED BY SULPHUR AND CARBON IN KILN ATMOSPHERES1

A study was made to determine the causes which make glaze surfaces susceptible to marking by metallic objects. The effect of carbon monoxide and of varying concentrations of SO₂ gas in the furnace atmosphere at 860°C, was investigated. It was found that (a) carbon monoxide does not produce surfaces which metal mark; (b) concentrations of from 0.1 to 1.2% Sop incrcase susceptibility to scratching with metals; (c) SO₂ in concentrations of 3% and higher will destroy the gloss of glazes on typical hotel ware and earthenware; and (d) concentrations of SO₂ of 3 to 12½% cause the glaze on one vitreous low-fired type of ware to metal mark.     

KILNS,FURNACES, BODIES,AND GLAZES FOR SMALL COMMERCIAL PRODUCTION AND EDUCATIONAL WORK1

Drawings and specifications for two small commercial kilns, one small test kiln, and a frit furnace are shown. Glazes suitable for use in the kilns are described. Shales and No. 2 fire clays are suggested for use. Reference is made to ware of commercial quality now being made in kilns of the kind indicated. Two sorts of copper red glazes are discussed and reference is made to the use of salt in effecting changes in the character of glazes. Fritted mat glazes are discussed and endorsed as superior to the raw sort, because of greater flexibility. A kiln atmosphere charged with vapors of common salt effects interesting changes in both the character of glazes and the usual colors produced by the commonly used oxides. A normally glossy, bright, and clear glaze becomes a vellumlike mat when fired in the presence of NaCl under certain conditions. A positive method of producing low-fired copper reds and lusters is described.     

A SLIP PAINTING PROCESS SUITED TO THE CRAFTSMAN WHOSE EQUIPMENT IS LIMITED1

The raw materials of the common stoneware business are used. The temperature needed is that of the maturing point of Albany slip, or cones 6 to 9. The kiln should be one designed to stand up under rather high temperatures. The ware is essentially once fired common stoneware decorated with a slip painting process.     

湖田窑出土黑釉瓷的产地研究

景德镇湖田窑窑址的南宋、元地层出土了类吉州窑、类建窑以及自具特色的黑釉瓷片。本文通过研究它们胎釉的化学组成,并与吉州窑和建窑黑釉瓷的胎釉化学组成进行对应分析,认为湖田窑宋、元时期也生产自己的黑釉瓷。其南宋、元堆积层出土的黑釉瓷中有吉州窑和建窑的产品,为当时各窑烧制工艺相互交流的佐证。湖田窑生产的部分黑釉瓷模仿了吉州窑的选料标准,应该是学习吸收吉州窑烧造黑釉瓷工艺的结果,这类黑釉瓷可能是南宋时期生产的。而另一部分黑釉瓷使用了质量较差的瓷土作为制胎原料,可能是元代时生产的。     

THE EFFECT OF HEAT-TREATMENT AND COMPOSITION OF SEMI-PORCELAIN BODIES ON CRAZING

Limits of Investigation.—The investigation was confined to practical semi-porcelain bodies and glazes, therefore, the results may be applicable only to this branch of the whitewares industry. Effect of Thickness of Glaze.—The thicker the glaze the greater the tendency to craze. The glaze on several pieces of dinner ware may appear to the eye to be of uniform thickness, but still have sufficient variation in thickness as to show difference in crazing behavior. It being impossible to obtain a uniform thickness of glaze by hand dipping there is a need for a mechanical dipper. An improved type of biscuit kiln which will produce ware with a uniform absorption is another need. Effect of Glaze Composition.—When sufficient change was made in the composition of a typical semi-porcelain glaze to cause a marked decrease in its crazing tendency, it was at the expense of other desirable properties. Effect of Body Composition.—The addition of 10.0% to 20.0% of “Hercules” clay to a general ware body greatly decreased its tendency to craze. No other change in body composition was found feasible, for when the change was sufficient to cause a decrease in the crazing it was at the sacrifice of other essential properties. Effect of Variation in Absorption.—Contrary to the general opinion among potters, the tendency to craze was not increased by every increase in absorption. An absorption of about 7.0% to 12.0% showed the most resistance to crazing. Effect of the Time-temperature of the Gloss Burn.—Tendency to craze is decreased by increasing the maturing time-temperature portion of the gloss burn.     

计算机模式识别在古白瓷研究中应用

本文利用前人对历史白瓷分析的数据，采用计算机模式识别进行处理，找到了各类白瓷窑胎和釉内“目标区域”。并利用逆映照法与一些样本点相近的逆映照点，根据逆映照点的工艺参数在实验室进行模拟，得到与古白瓷较一致的效果。这为仿制过程选择工艺参数，提供了新的有效方法。     

宋瓷艺术的符号学解读

从符号学的角度研究宋瓷艺术,通过文献法、调查法、对比法总结出其造型、色彩、图形装饰、工艺装饰等符号,通过历时性和共时性分析等方法解析宋瓷艺术符号的符号学特征及其意义构成的缘由,并运用符号美学解读了宋瓷艺术符号背后的文化内涵及象征意义。