The necessary heat for brazing is usually supplied by a flat-topped forge or brazing table such as is shown in Fig. 253. This forge uses gas or oil fuel forced into the flame by compressed air. The air is necessary for the complete burning of the fuel to avoid a soot deposit on the work.

A forge table, similar to that shown, but with air-blast connection as in the blacksmith's forge, is much used for charcoal or coke fuel. This gives a less intense heat than gas or oil and is preferred by many workmen for lighter brazing work. A blacksmith's forge with charcoal or coke fuel may be used for brazing.

A compound blowpipe with rubber-hose connections to gas and compressed-air supply is used as a portable heater where work cannot be brought to the furnace.

Small articles may be brazed by means of the mouth blow pipe, or may be heated in a charcoal fire without air blast.

Fig. 253. - Brazing Forge.

Some compositions of brass are difficult to braze because the zinc in them tends to melt out. Also they are usually very brittle when hot and must be handled carefully and allowed to rest quietly and free from air drafts until cool.