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Forge Welding in a Coal Fire with Flux:

Goals:  Keep oxygen off the iron being forged by:

                Keep only well packed (no hollow areas) coke in the fire pot.

                At least 4” of coke under the iron being heated (use fire pot at least 3” deep, 4” or more better).  Can make shallow fire pots deeper by covering the table with refractory or even regular brick.  Can also form deeper fire pot with clay or refractory on table.  Also, can have deeper pile of coke than fire pot (control fire spread with water).   

               2” coke over the iron being heated helps, but need to be able to see the iron through the coke.

                Use flux such as borax or Easy Weld on the iron as a barrier to oxygen.  Applied at an orange heat

Keep other impurities from the iron.

                Burn no green coal (unburned coal) near the iron being heated

                Keep copper/brass and other impurities out of the fire

                Use clean iron.  Sometimes wire brushing or grinding the iron is necessary to clean the surface.

                Use flux which coats the iron and is acidic to clean the iron.  Borax is acid at approx.. 2000

degrees F.

Get iron hot enough

                Same high yellow color as the fire, sparking is normally too hot

                Salt and pepper spots on the heated iron indicate iron not hot enough.

                Green flames coming from flux indicate iron is ready.

                Surface of iron looks liquid/like wax when iron is ready.

                All pieces to be forge welded at the same color

                Keep iron off the cooler anvil as long as possible.  Don’t touch iron to anvil until last second.

Scarf the iron so ends are paper thin.  Weld thin ends first before they cool.

Hit the iron softly at first until iron is stuck together which keeps iron from sliding away from each other.  Strike harder once iron is stuck.

Other:

Easy Weld is easiest to weld with.  It includes iron filings.

Anhydrous (water removed) borax is nice since it doesn’t foam, but not necessary. Regular borax is fine.  20 Mule Team Borax from grocery store is typical.  Don’t use borax soaps.

Wrought iron welds easier than mild steel, but requires higher heat.

High carbon steel welds at a lower tenperature than mild steel.

Copyright © 1999 Shady Grove Blacksmith Shop, LLC. All rights reserved.
 Revised: December 31, 2015 .

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