Apple/Potato quench

[SteveW]

I have heard and read a number of tales regarding the quenching of tools in an Apple or a Potato. The idea sounds a bit potty at first, but on reflection maybe the stories are not so far fetched, though the idea that potatoes impart extra carbon into the steel during the quench make me wonder if its just a wild Blacksmith story handed down to mock the gullible.

Any wiser heads than mine want to tell me if it's a likely method of quenching or just a tall tale?

[GobblerForge]

I would think that the first reaction would be that the quenching would start but then as the heat rises inside the potato or apple that the quench stops. There is nowhere for the heat to be rapidly dissipated as in a slack tub. this is the reason for keeping the steel moving in the tub.
Gobbler

[ThomasPowers]

Weygers mentions a Melon quench in "The Complete Modern Blacksmith" and stated that the blade ended up with a hard edge and a soft spine and he even used it to clip nails, mushrooming the spine but not damaging the blade.

Quenching gravers into candle wax is also a time proven method.

Gaining carbon? No not enough time at temp to do that effectively.

[Rob Browne]

If you think about it, melons would work on blades but I'm not too sure of anything heavier. They are mainly water that is contained so if they are cut to the shape of the blade edge it could be put into the melon at hardening temperature and harden the edge but the spine would remain soft as its never hardened at all. The melon would dissappate the heat quickly from a thin edge but not from a heavy object so its probably really restricted to edge blades.

[CBrann]

I have heard the story about sewing needles and potatoes ... and I would extrapolate it to other long slender pointy things... but thats as far as I would go

[Dave Budd]

no reason why it wouldn't work fine, depending on the shape and size of the tool being quenched.

I did an April Fool's post on British Blades a couple of years back where I hardened a blade in a banana. When I took the pictures to back it up, the xxxx thing actually worked!

here is the original thread with pics:
Heat Treating with Fruit - British Blades :: Custom Knife Making

[pkrankow]

Other than the scale that sounds yummy! If I had bananas in the house I would fry one up and have it with ice cream!

Phil

[MattBower]

I'd expect it would probably work OK on either extremely fine cross-sections -- like needles -- or on steel that has a very forgiving cooling curve. (Even then, you'd still need enough mass of quenchant for the blade size.) Stuff that will air harden in thin cross-sections should also harden in something like an apple or potato. But it's really just a gimmick.

No way you can carburize like that. Too little time and temp.

[jockaneezer]

i have made small diameter (up to 5/16") reamers and D bits for use in model engineering applications from silver steel bar (01 I think) heated to red then plunged into a potato with no need to temper. mostly used on brass though. with the bonus that if you have a few to make, you can eat the spud afterwards !