Let me make one thing perfectly clear, I am not commenting on the quality of the steel used then and now. I am not saying that the old steel was better than the new steel, I have no idea and for this discussion, I really don’t care. That is not the point. For the quality of steel is only one small, I repeat small portion of the overall equation.
By laminated blades, be it chisels or plane irons; I mean tools made largely of wrought iron with a thin veneer of steel forge welded to the cutting edge. Now I would like to take to task those who say that this was done because of economy; steel is more expensive than wrought iron. In the nineteenth century steel costs 5 times that of iron and the steel on these old tools is usually less than 10% of the blade. Then there is the two or three heats it takes to forge weld the steel to the wrought iron. There is no economy, it would have been cheaper to make them of solid steel, but they didn’t and here is why.
First steel will hold an edge longer than the softer wrought iron and the iron could not be hardened like steel. The steel had to be reduced by forging to the thin veneer before it is forge welded to the wrought iron. This forging, both in making the thin slips of steel but the forge welding to the iron as well, compacts the grain of the steel. It even happens today following the same process, and the tight grain in the steel produces a higher quality steel.
However the most important result of this process is that the completed forge welded laminated [laid] steel blade can be hardened by quenching in brine, producing a very hard and brittle steel. If it were made of solid steel then it would need to be tempered in order to remove some of the hardness or the tool would break as the solid steel with be too brittle. Made largely of wrought iron, which can’t be hardened, the steel can be hardened much harder than a solid tool. And because it is supported and protected by the soft iron, the steel can be left very hard from the brine quench.
Some say the older tools have better steel, I am not sure the steel was any better but the process did leave the thin veneer of steel very hard, holding an edge longer. And when grinding and sharpening only a small amount of the hard steel is ground/sharpened while the bulk of the tool made of wrought iron is easy to remove.
So let me say it once again, it is the combination of iron and steel that makes for a better blade, probably reduces chatter [as opposed to a solid steel blade], puts the center of gravity toward the cutting edge of tapered plane irons and can be made much harder because of its unique structure.