V80 NEW YORK STATE MUSEUM 



oil. Such, colors are very susceptible and hence have to he burned 

 in muffles. They are also strongly influenced by the degree of 

 temperature to which they are subjected, and hence the different 

 colors are often burned separately, those standing the highest tem- 

 perature being applied and burned first, and those most affected, 

 last. This method of decoration requires repeated burning, but it 

 permits a variety and richness of color not attainable in under- 

 glazed work. 



In preparing these colors, it is highly essential that they be 

 ground as finely as possible, and underglaze colors are generally 

 mixed with water before being applied, the porous body of the tile 

 absorbing the moisture and causing the color to cling to it. If this 

 does not happen, the color must be mixed with oil, in which case the 

 ware must be fired lightly at first, to burn it off. 



At the present day, where a number of tile with the same 

 design are made, the design is applied mechanically. This is 

 effected by a process of printing, the pattern being printed on paper 

 from a plate and this transferred to the tile. Usually but one 

 color at a time can be printed on the paper. But in more recent 

 years it has been found possible by a process of chromolithography 

 to print several colors on the ware at once. 



