smoke hood materials

[shanew8869]

ok so very green blacksmithing newb here. quick question about using galvy. i know the fumes are nasty and its not to be heated but are there any thoughts about using it for a half hood? would it get hot enough to cause a problem in the smithy? any thoughts would be appreciated.

[TASMITH]

The hood should never get hot enough to cause a problem in use. The problem lies in using galvanized to make the hood in the first place. If it is formed all by cold work, then their is no problem.But if you try using a welding torch or electric welder to assemble, then you are in danger of heavy metal poisoning from fumes generated by the galvanizing. Any high temperatures, such as those generated by even a propane torch will cause the galvanizing to break down releasing Highly Toxic fumes. Better to stick with plain mild steel if you can get it.

Terry

[thecelticforge]

I wouldn't risk it anywhere near a fire myself. Remember Paw Paw.

[TASMITH]

In Paw Paws case he put galvanized steel directly in his fire. The temperatures even at the surface far surpass the levels required to cause the galvanizing to break down.
i have a side draft chimney on my forge. The box portion is made of regular thin sheet steel but the stack is 10 inch galvanized steel. The box temperature gets up to about four to five hundred degrees when flame from the coke fire goes in, and the stack sits about twelve inches up from the base of the fire. The stack itself has never gotten any hotter than about four hundred degrees which is well below any point of breakdown of the galvanized.

The opening on the intake box of the chimney is of sufficient size to draw cooler air in from around the sides of the fire and keep the stack temperatures at an acceptable safe level.I "WOULD NOT" however recommend that he make the intake box out of galvanized as flame impingement on a localized area of the box "COULD" cause a problem.

Terry