METHODS OF BURNING POTTERY IN THE VICINITY OF MANILA 

 AND THEIR INFLUENCE ON THE QUALITY OF THE PRODUCT' 



By J. C. Witt 



{From the Laboratory of General, Inorganic, and Physical Chemistry, 

 Bureau of Science, Manila) 



TWO PLATES AND ONE TEXT FIGURE 



Throughout the Philippines there are groups of small establish- 

 ments for the manufacture of clay products in localities in which 

 the necessary raw materials can be easily obtained. Often 

 brick, tile, and pottery of various sorts are manufactured in 

 the same district. Although the small equipment and limited 

 output of the individual manufacturer is likely to give one the 

 impression that the industry is of relatively small importance, 

 the census report - shows that even fifteen years ago the annual 

 production was valued at 66,499 pesos.-^ No recent data are 

 available, but the indications are that the output is increasing. 



In the potteries in the vicinity of Manila the principal articles 

 manufactured are flower pots {paso), large jars {hang a) , often 

 used as containers for water or sugar, round-bottomed bowls 

 for cooking rice (palayok) , and small wood-stoves (calan) . 

 The raw materials and processes of this district are similar. A 

 clay from the rice fields and a sand from deposits along Pasig 

 River are used. The clay is spread out, allowed to dry, and then 

 pulverized. The sand is passed through a screen made of split 

 bamboo that corresponds to a laboratory sieve having about 8 

 meshes per centimeter, and the part retained on the screen 

 is rejected. Two parts of clay and one of sand are mixed, water 

 is added, and the material is kneaded to the desired consistency. 

 Apparently there is no uniformity in the time this mixture is 

 allowed to weather. Often some of it is molded the same day 

 it is prepared, while the remainder is allowed to stand until it 

 is all used. 



The molding is accomplished by the aid of very crude potter's 



' Received for publication May 14, 1917. 



■ Census of the Philippine Islands. Government Printing Office, Washing- 

 ton (1905), 4, 522. 



' One peso Philippine currency equals 100 centavos, equals 50 cents United 

 States currency. 



'Cf. Adams and Pratt, This Journal, Sec. A (1910), 5, 143. 



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