Chippendale TV programme - blacksmith sequence

Finely powdered Prussiate of potash was once used, sprinkled on, when it had decomposed and disappeared the item was quenched. Was a quicker method of case-handening..

Tom

Geoff,

I didn't see the program, but if it was sprinkled on prior to hammer welding it could be fine silica sand or borax used a a fluxing agent.

Andrew Mawson

I assumed it was powdered bone for case hardening. But I'm a novice:(

Ken.

I would expect Prussiate of Potash to be Potassium Cyanide, which is still a standard case-hardener, but I wouldn't expect it to be a pure white powder for that job.

Ken.

Expecting and actuality are two different chemicals in this case..

Tom

I agree with Andrews interpretation, since the point was stressed that tip of the chisel (about 1" long) was made of tool steel costing ten times the cost of the iron in rest of the blade. Of course one must remember that the visual images of any film of a technical nature are pure B.S. but are chosen for visual impact with complete disregard to any technical advice given by the technical advisers. Anyway case hardening would not survive the initial grinding let alone subsequent sharpening!

A good example of my point is that when the subject of sharpening was mentioned the only image was of use of the grinding wheel which would have very rarely been used after the initial sharpening. The normal sharpening being done on a whetstone, but that does not present such a photogenic shot.

Cheers Brian

not survive

Nice to have more bones on the subject.. However if tool steel was being welded to the shank it would have borax rather than sand being sprinkled..

Tom

Prussiate = a salt formed by Prussic acid (HCN) Potash = Potassium (K)

Hence Prussiate of Potash = KCN. Where am I going wrong?

Ken.

I saw it - looked like Borax used before hammer welding the steel tip on the blade blank.

-- Steve Blackmore

You forgot the iron.

The "white" appearance was probably due to the yellowish lighting conditions under which the sequence was shot.

HTH.

Ah! Thanks for that. Have some in the shed, must try it.

Ken.