Thread: Silver Steel, Carbon, stainless

I balieve the number of folds is 16 which means 65000 and some change layers for katana.
Recently one of the knife makers over at the Knife forums did 1 million layers, pretty cool stuff.
1 MILLION layer damascus billet!!

Originally Posted by Mike Blue

I know that you're not trying to hurt anything. It's easy to watch a show and the first time you observe a process and think one thing might be going on, when in fact, something else is happening. These subjects have been worked over fairly well on this site. I've watched all those shows. While NatGeo has a good reputation, and I enjoy watching my friends demonstrate on TV, the producers often err about things that make those who know about the process cringe.

It's no different than the source of many legends about steels. They are magical stories because at the time (pretty much any time before the early history of real chemistry) that's the best way to understand what the smith was doing. Knowledge about what's going on inside that bar of steel is considerably better now.

30,000 Layers, or more depending on the starting layer count, is very possible in 15 folds. The death of the idea that 30,000 Folds happens is the simple fact that scale formation would burn away all the steel you started with long before any useful object resulted from the work.

Okay, I ran out to the shop and Spazola and I just measured a piece of scale from the floor by the big hammer. I specifically use methods to reduce scale formation so we're already discussing a variable that may not hold true for other shops. This also means that in my shop this is a conservative estimate of scale loss. The pieces of scale measured in the caliper average 0.005 inch thick.

Now, scale loss is a four sided effect on a billet. To be even more conservative, we only calculated the scale loss from two sides of the billet, the sides that will be exposed to the atmosphere, not the side between slabs being welded and not the sides that are not (which would double the amount of scale). 2 x 0.005 inch = 0.010 inch x 30,000 = 300 inches of material loss by the time you get to 30000 folds. All of us here today think the math is correct, but if it's not I'll agree to a change in the answer. And that's only two sides. It will go faster adding the remaining two sides in, or adding in less controlled forge operations/processes.

A 300 inch thick piece of steel is much more than I could lift, and I don't have a forge big enough to hold it. A 1.18 diameter bar 12 inches long weighs 4.8 pounds. Multiplied by 300 that's 1200 pounds roughly.

In the end, much better information produces less myth and magic. It also takes time to accumulate.

Yeah I know what you mean, there is a great documentary on the history of the samurai sword. In the documentary it said that they understood adding charcoal to the iron made it much stronger but had no idea what carbon actually was. That these ancient blacksmiths were more like alchemist in a lot of ways. What I found really found interesting was the religious myth surrounding the sword, like every sword had a living breathing soul of its own. A psychologist on the show said that the neat thing about their sword having a soul was that when a samurai killed someone, the sword was to blame making it easier on the conscience.

Originally Posted by Mike Blue

Several of the points you discuss beg to be refuted. I'll take on two since I'm trying to get ready to teach this stuff tomorrow. I wish you could be here.

Katana, made in Japan, are forged from tamahagane built into a billet of oroshigane then forge welded. No sword has ever been folded 30K times. The carbon content of tamahagane is 1.4-1.6% as smelted. By the time the billet has been forged into a blade the carbon content is reduced to between 0.6-0.7% depending on the particular sword school the smith attended. Forging a katana does not add carbon into the steel.


This does not mean that the smith does not understand how to add carbon to low carbon irons. The techniques to add carbon to irons are several. Attempting to add carbon from organic ashes is considerably less efficient than simple adjustment of the atmosphere of the forge and taking the time to allow the carbon to diffuse into the iron and considerably less efficient than packing the iron in a closed atmosphere box containing sources of carbon and preventing the carbon from binding to oxygen, its preference to iron.

The rest of the essay needs as much work. At least give eHow credit for most of your citations.

Maybe the confusion is the term should be Layers, not folded.

If you take a piece of iron and fold it 16 times you get over 30,000 layers.

I should have read the other posts first.

Originally Posted by Crotalus

Maybe the confusion is the term should be Layers, not folded. ...

I hoped to emphasize that point. Myth and magic can be very entertaining but are often based on coincidental observations. Separating those things from how things really work is equally interesting, and easier said than done sometimes. Either perspective should eventually lead to understanding and accepting the other if the minds are open in between.

And now I know it is my razor's conscience that is responsible for nicking me.