Y58 NEW YORK STATE MUSEUM 



TEERA COTTA 

 General properties 



The increasing tendency of architects to place considerable adorn- 

 ment on the exterior of buildings has led to the extensive adoption 

 of terra cotta as a cheap substitute for stone. 



The advantages ascribed to it are 

 Durability 

 Cheapness 

 Permanent color 

 Resistance to fire 

 lightness and strength. 



The term terra cotta is usually applied to those ornamental clay 

 products for structural work which are more than 8 inches square. 

 If the pieces are under this size they are called ornamental brick. 



Terra cotta objects should be burned to an even color, the pieces 

 should be of regular outline and not show signs of warping, neither 

 should they discolor, superficially. The hardness should be above 

 6 in the scale, that is, it should resist scratching with a knife. 



Terra cotta is seldom vitrified, but the slip covering the surface 

 generally forms an impervious coating, and also serves to give the 

 desired color to the ware. 



At first the forms produced in terra cotta were comparatively 

 simple, but improvements in methods and experience have greatly 

 extended the possibilities of the material. Among the more re- 

 cent uses is to be mentioned its employment in columns and balus- 

 trades. 



In the manufacture of balustrades the solids and voids should be 

 made in the proper proportions to prevent Warping and cracking 

 of the ware in burning. 



The strength of terra cotta brackets has been well shown by the 

 following experiments :^ 



' An important and instructive series of articles on " Terra cotta in archi- 

 tecture", by T. Cusack, has appeared in the Brickhuilder. 1898. p. 7, 55, 98^ 

 142, 185, 230. 



