312 



IMPROVEMENT OF TILES. 



XII, 



Method of increasing the Durability of Tilts: by Count 

 von Mellin*. 



effectual. 



Method em 

 ployed. 



Methods of J.VJI.EANS of increasing the hardness of tiles, and conse-* 



rendering tiles q ue ntly their durability, have been sought, without the dis- 

 more'durable. . , _. . * . , . . . p 



covering ot any sufficiently cheap and simple tor common 



Glaring ex- use * Such is the glazing or varnishing of tiles, which is in* 

 pensive. deed very good, but too expensive, to be generally adopted. 



Coating with Tarring tiles has been proposed ; and this process appear- 

 ur cheap and ing to me easily practicable and not expensive, I determined 

 to make trial of it on one of my roofs, that required a great 

 deal of repairing. Providing some of the largest brushes 1 

 could get, L and an assistant set ourselves to coat the upper 

 side of my tiles with tar liquefied over a gentle fire, and 

 kept moderately hot. Four persons were employed to hand 

 \is the tiles, and, when tarred, to lay them in the sun to dry ; 

 which took three or four days, it being then the spring of 

 the year. It is proper to say, that I had set apart the best 

 tiles, or those which appeared most thoroughly baked; and 

 that I exposed the others to the sun, that they might be 

 warmed and receive the coat of tar more easily. After the 

 process these appeared as if coated with a reddish brown 

 varnish. Four hours were sufficient for the preparation of 

 two thousand. 



Near my house was a tile kiln", which was just ready to 

 draw. As soon as it was sufficiently cool, to allow the tile3 

 to be handled, I had as many taken out, as left in the inte- 

 rior of the kiln sufficient room for a few people to coat them. 

 with tar. While two of these were tarring the tiles, three 

 others were employed to give them, receive them when 

 tarred, and lay them in a corner of the kiln, where the heat 

 was reduced to that of a vapour bath. When the kiln wa* 

 quite cold, the tiles were perfectly dried, but they had not 

 such a shining coat as the former, because the great heat 



Another me 

 feed. 



* Sonnini's Bihlioth. physico-econ. Oct. 1800, p. 243. 



had 



