METHOD OF MANUFACTURING BRICK 



16a 



the kilns. The combustion of the coal in them, the manufacturer 

 claims, supplies the necessary amount of heat to the outer portion 

 of the kilns which are not sufficiently heated by the arch fires. 

 Double-coal bricks sell for about $2.50 per 1000, and usually bear 

 some distinguishing stamp, but they are not as strong as the 

 other brick. It takes two setters and four wheelers about one 

 day to set an arch of 35,000 brick ; two men will daub the out- 

 side of a 15 arch kiln in one day. 



Having "walled-up" the kiln with double-coal brick and 

 daubed it over, the next step is to start the fires and burn the 

 bricks. The principle of the process is essentially the same, 

 whether wood, coal or oil are used as fuel. 



First, every alternate brick of the " burnt platting " is stood on 

 end to allow the " water smoke " or steam to escape as quickly as 

 possible. A fire is then started in the mouth of each arch. 

 When coal is used the fire is started on the windward side of the 

 kiln so as to allow the smoke to blow through the arches. 



The fire is also started from the other end of the arch, and the 

 two fires are then built up slowly till they meet in the middle. 

 The time of crossing the fires varies ; with machine-made bricks 

 the fires should not be crossed as quickly as with hand-made ones. 

 Along the Hudson the time of crossing is from 40 to 60 hours. 

 The steam should escape evenly all around the top, and the upper 

 limit of the fire should follow directly on it, the steam acting as 

 a blanket, and its lower limit should be even. It is the duty of 

 the foreman to watch the burning carefully, and increase or ease 

 up the steam in any one arch, according as it is coming off too 

 slowly or too rapidly. The fires are increased until the " water 

 smoke " changes to a bluish black smoke, and at this point the 

 fire can be seen at night time coming from the top of the kiln. 

 The kiln is now " hot " and the bricks commence to shrink or 

 " settle " and all the platting is turned down. Up to this point 

 care must be used to gradually increase the heat. The bricks 

 now get their heaviest heat, and the oxides of iron are changed 

 to the anhydrous peroxide, giving the bricks their red color. If 

 the heat in the arches is too great, the bricks run, stick together 

 or become distorted and cracked. After the firing has been done 

 the doors are all closed and plastered over to prevent any air 

 from entering. 



