EQUIPMENT FOR BLACKSMITHING; PROCESSES 197 



Use a very light blast at first. As the fire burns, add green 

 coal. When the fire gets strong, surround it with a ring of 

 green, dampened coal, except toward the front, which should 

 be kept open for the insertion of the iron to be heated and 

 used to hold the iron while being heated, and for the tools. 

 These should be kept in a horizontal position. As the work 

 proceeds and the fire extends into the ring of green coal, it 

 may be dampened to hold the fire to a limited area. Green 



coal may be added at the 



GREEN GOAL-T; v PAN y 



rear and the sides, but the 

 fire should not be disturbed 

 by poking it. As it burns 

 from underneath, cinders 



should be raked out to 

 FIG. 175. Cross-section of forge. . . 



keep the fire clear, and 



the coal should be gently patted down with a small shovel. 

 Continuing this process will keep a clean, well-confined and 

 fresh fire. Fig. 175 shows a cross-section thru the fire-pot. 



As iron heats in the fire, the following shades of color will 

 appear, indicating the proper condition of the iron for certain 

 classes of work: 



a) Dark blood red (block heat). 



6) Dark red, low red (finishing heat). 



c) Full red. 



d) Bright or light red (scaling heat). 



e) Yellow heat. 



/) Light yellow heat (good forging heat). 

 g) White heat or welding heat (beyond this, iron will burn) . 

 173. Welding. Upon continued heating of wrought iron 

 or mild steel, the temperature increases, the metal becomes 



