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What is the advantage of NOT running your forge "Lean"?

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I'm curious, because, the way I see it, there is no advantage to running your gas forge with a "rich" environment. This is because scale does not form as much when the forge is lean and there is less production of CO. Are there any reasons why it would be better to run your forge rich then? I'm stumped. :blink:


Thanks,
Zachary

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Best to run it balanced. Rich means you are wasting fuel that doesn't get burned completely. Lean means you are cooling the flame with too much air and not putting full BTUs into the forge.

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Lean means *more* scaling; rich means *less*. Lean means more decarburization; rich means less (in general).

Unless you are doing blades a balanced to slightly lean is the better especially wrt CO production.

If you are doing blades it depends a lot on your skills. less experienced bladesmiths tend to do more heats and leave their stock in the forge more and so have more issues with scaling and decarburization.

Actually for one ornamental piece I did, I tuned my gasser way lean to get a massive scale layer that I then broke off when cold to leave a pebbled surface for a dragon head door knocker's skin.

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Lean produces more scale?? Huh. I thought scale was oxidation, so a more lean environment would have less oxygen. Is this not the case?

By the way, blades would be the majority of work that I would be doing.


Zachary

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No. A lean environment means there is less fuel than the available oxygen can combine with to burn. In other words after all the fuel has burned there is still free oxygen in the forge, which will oxidize any good other good candidates that it can find. Steel is a good candidate for oxidation. That's where scale comes from.

A "rich" environment is rich in fuel -- all the oxygen is consumed, and there's still fuel left over.

Synonyms for "lean" and "rich" are "oxidizing" and "reducing." Lean = oxidizing. Might help you remember.

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I think the terms actually date back to gas engines with carburetors where rich means you were putting *more* fuel into it and you could smell unburnt fuel coming out the exhaust. Lean meant you were putting less fuel into it.

I think you should study a bit more basic forging before starting bladesmithing; it will make bladesmithing much less frustrating if you have the basics down before having to deal with the fussy bits of bladesmithing.

Have you got a copy of "The Complete Bladesmith" yet? You should be able to ILL it at your local public library. (Of course once you see what's in it you will probably want your own copy...)

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That makes a lot more sense. Thanks Matt

That's a good idea. They actually don't have that book in any library near here, so I might order it soon. We'll see. I just got a few books from the library on blacksmithing techniques yesterday.


Zachary

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Note the ILL: it stands for "Inter Library Loan". It's a process where you can check out books from *other* libraries in the system often over 100 and including big city and university libraries. Here in Rural New Mexico the local library can get me a copy of a book that a 4 year standing order at Amazon and regular searches at ABEbooks.com has not been able to find for me.

So I would talk to the folks at the library about ILL---makes it a whole lot easier and cheaper as you can preview books to see if you want to buy them.

Remember you're paying for the library might as well get you're money's worth!

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See, I've heard of them before, but I never knew what it was really. I've put plenty of books on hold, but never knew that you could request a book not in the catalog and have it transported to your library. Thanks for telling me about this! I just did 2 ILLs for the $50 knife shop and the complete bladesmith.

Zachary

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No. A lean environment means there is less fuel than the available oxygen can combine with to burn. In other words after all the fuel has burned there is still free oxygen in the forge, which will oxidize any good other good candidates that it can find. Steel is a good candidate for oxidation. That's where scale comes from.

A "rich" environment is rich in fuel -- all the oxygen is consumed, and there's still fuel left over.

Synonyms for "lean" and "rich" are "oxidizing" and "reducing." Lean = oxidizing. Might help you remember.
Good points Matt! Yeah, we should use oxidizing and reducing (and neutral) rather than rich and lean. Rich and lean describe the combustion while oxidizing and reducing describe their effect.

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When you live out in the boonies and do esoteric research ILL is a massive help! I thank Ben Franklin *often* for the public library system and Andrew Carnegie the steel baron too!

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