[Jeremy V. Krause]

Given how long I've had this hobby you'd think I would know this but I don't clearly know the difference between shear steel, blister steel, and crucible steel.

Could someone enlighten me about this. I am looking for the "what, when, where, why, and how" of the issue.

I tried wikipedia but didn't get a clear enough handle on this- wikipedia can be like that. . . .

[Timo Nieminen]

Depending on how you define "crucible steel", blister steel can be a specific type of crucible steel.

A broad definition of crucible steel is that you heat iron and some carbon-contributing material in an enclosed crucible in a furnace.

If you use wrought iron + charcoal (or similar), the carbon will diffuse into the iron. You don't need to melt the iron, but the colder you keep the crucible, the longer it takes. This, non-melting, heating for a week or 2, starting with iron bars in charcoal, produces blister steel.

These blister steel bars aren't very homogeneous, so for practical purposes, one wants to weld, fold, twist, etc., to produce a homogeneous product. This welded and homogenised blister steel is shear steel.

A purist might not want to call blister steel a crucible steel, because the iron bars and charcoal are packed in a big stone pot, rather than a ceramic crucible. It's also much larger.

Less fussy is that crucible steel is sometimes (often? usually?) restricted to processes in which the crucible contents get hot enough to come out in a relatively homogeneous lump (after cooling). Another method of homogenising blister steel, other than welding to make shear steel, was to heat chunks up in a crucible, to melt them this way. This product, crucible steel made from blister steel, was the usual English version of crucible steel. This is slightly funny crucible steel, in that the crucible is fed with a single type of material (as opposed to iron + carbon), and it's removed molten, rather than cooled into a solid chunk in the crucible.

There are two types of classic crucible steel. Iron + charcoal or similar (chunks of wood will do), and iron + cast iron. This last type, iron + cast iron, is the real crucible steel for the strictest of all purists. Low carbon iron, + cast iron at 3-4% carbon, gives a nice high carbon steel when mixed. The usual ratio was about 50/50, which gives carbon contents of about 1-2%, which is high by European standards for use in blades. Carbon content will go down a bit, but the end product is still remarkably high carbon. Thus the reputation of Central Asian/Middle Eastern/Indian blades as hard and sharp, but brittle.

Blister steel and shear steel are well-defined. "Crucible steel" is much fuzzier. "Wootz" is also a fuzzily-defined thing, varying from synonymous with Central Asian or Indian crucible steel, through to following a much narrow recipe/process.

[R D Moore]

Hey Jeremy
Our own Ric Furrer is an ideal source of information and answers to your questions:
http://doorcountyforgeworks.com/Steel_Making.html
His site has a video of making shear and blister steels I encourage everyone with an interest in seeing. They're well done for these types of presentations (in the smithy and not a studio) and the information is clearly presented. I bet he'd answer an email, too.

[Jeremy V. Krause]

Thanks Guys,

So blister steel is a transitional product toward the goal of shear steel?

I had the impression that blister steel and shear steel were different terminal products.

[Timo Nieminen]

[Jared Smith]

[Richard Furrer]

Jared,
Also:
It is thought the term "shear steel" came to be associated with this material in England in 1760's by William Bertram because a stamp in the shape of a pair of shears was used to mark the bars for sale.
Bertram was German and went to England to find his fortune.

K Barraclough wrote a great set of books on Blister and Crucible steel.

Ric