All of the analyses will produce vitrified, trans- lucent porcelain between cone 8 and cone 10. In descending order from (a) to {e) they will be more plastic and workable but less vitreous and translucent with more inclination toward crazing unless they are fired very slowly. Thus the working properties and the fired qualities are in some opposition to one another, and it is quite true to say that the more ae the porcelain body the longer it must be red. It is a fairly simple matter with a slide-rule to cal- culate recipes to fit these analyses. A little variation in the silica content will make little difference, It is unlikely that you will achieve a body that can be thrown with ease unless you include two to five per cent bentonite in every recipe. To diversify the fluxes by using a number of different feldspars and alumino-silicates will likely improve the fluxing of the body, but as most are higher in alumina than feldspar (relative to the fluxes) they will also diminish the quantity of clay in the recipe. Above all things, use the finest-grained silica which you can obtain and soak the firing as. long as you can endure. If you use simple, clear, transparent por- celain glazes they will bring out the best qualities. If the body has a high degree of translucency it is Surprising just how glazes can be which are at the Same time highly coloured. It is not colour which makes glazes opaque. MAKING A PORCELAIN BODY: EMPIRICAL MEANS If the chemistry makes you nervous, a porcelain clay body can be made by empiral means. As a beginning, take this recipe: 50 China Clay, 25 Felspar, 15 Quartz, 5 Bentonite. Fire it. It is quite low in silica and the glazes will likely craze. If they do, increase the quartz in the body until the glazes Fit. The recipe will be unlikely to take more than 29 parts quartz. If the firing cycle is short, so much quartz may be needed that the fired body will begin to look "dry" and plaster-like, although the body may be translucent. This is an indication that the recipe has run out of fluxes, and you must slowly ee