Four folks I have quite a bit of respect for have actually gone to Japan to see how these chisels and plane irons are made (obviously more than four have made the trip, these are the folks I've listened to). Jim Kingshott, Leonard Lee, Robert Meadows and a member of my local woodworker's guild. I know enough about the four to have established a high opinion of what they have to say. I don't think they've snookered me and I don't believe they've hyped me, but I've been wrong before.
They all seem to agree that the first and absolutely most important factor in Japanese chisel quality is the skill of the blacksmith, due to the process of making the steel, forging, welding, heat treating and tempering. The type of steel (blue, white, sword steel, damascus, etc.) is secondary. They also seem to agree that few if any Western chisels are of as high a quality as the better Japanese chisels.
The terms blue and white come from the color of the labels Hitachi puts on its steel. Blue has more alloys added than white, but both are from pure sand iron. Blue steels warp less during hardening, can be cold-worked and will hold an edge longer than white. Blue also takes more skill to work and is more brittle and subject to more chipping in use than white. It also comes in thicknesses which can be used directly for plane irons and chisels. White steels are more flexible and actually will pack into a denser structure when the chisel is smacked with a hammer. White needs to be worked down to the thickness required for edge tools as we know them. Each of these steels has it's place, but my opinion is that properly worked white steel is probably better suited to edge tools.
Now, any two chisels, say from white steel, also can end up with very different properties depending on how they were made by the blacksmith, that's why I claim "properly worked" above. There are 5,000+ toolmakers in Japan, and not all are exceptional. I'm sure they fall into the same categories as any other industry - probably most are OK, some stink and some are indeed exceptional. So comparing anything on price alone is rather silly since you are only comparing what the importer chooses to show you. Is the "limit" of "goodness" in a chisel $30? $50 $150? There's certainly no way to answer that one, and I'm sure that among the 5,000 blacksmiths someone makes a damn fine $25 chisel and someone makes a marginal $100 chisel.
The lamination process for the steel in theory came about due to the scarcity and price of tool steel. Obviously laminating a softer carbon steel to tool steel also allows quicker and easier sharpening, as well as some dampening properties. Just my opinion, but I have to think the latter reasons have more to do with it than the former, but I don't really know.
The iron used prior to 1900, such as can be found in scrap like old anchor chains and boilers, is indeed better suited for edge tools due to impurities which are present, like silica, which are nowadays filtered out of steel. It's in fact true - when they start a new batch of chisels, the tops blacksmiths will literally go out back and cut a chain link off a huge anchor chain, or cut a section off an old boiler.
The entire process, from melting the steel to forging all the way to final finishing is proprietary to each blacksmith, and by any reasonable account it takes 10-15 years to become proficient - if one is lucky enough to be trained.
So how would one judge the quality of a japanese chisel? Well, in order:
- Quality of the blacksmithing
- Type of steel and how it was worked
- Quality of the shaping of the blade
- Quality of the grinding
- Fit of the blade to the ferrule
- Fit of the ferrule to the handle
How do you judge the most important factor above? You'll have to look for the signs. For instance, while most chisels are rough-forged and then ground, my white steel set is completely hand forged, meaning more forging. The science of forging and edge tools says more forging equates to a higher quality edge. Any shiny surfaces you see on a chisel are ground - if they are matte black that means they required no final grinding and were made accurately to begin with. My blade-ferrule joints are full black, unground. I really like them, not only for the quality at hand, but sure, for the story behind the quality. Nagaoke-san sounds like my kind of guy :). BTW, the other bitch with blue steel is that it can pit or crack if the forging is not done correctly, and you'll never know it until you try to use it.
Hey, no snoring out there.
Hopefully the above addresses the burning issue WRT a $150 chisel cutting five times better than a $30 chisel - there's no way in creation to answer that question. Two $30 chisels could be worlds apart WRT overall quality, and the typical person attempting to make that judgement is staring at five brands of chisels in an import catalog.
If you want to shoot for apples to apples, something we can all relate to, how about the LN #4 vs. the Holtey. Does the Holtey cut 15 times better than the LN? Of course not. Is it worth 15 times the price? Quite possibly, yes. Those are two separate and distinct matters. The Holtey is absolutely, obsessively fussed over by hand, every detail being wrought and finished by hand, each one a result of one person's efforts. It's eventual owner will surely appreciate and attach value to those facts. Hmmm, sounds alot like the chisels which started this whole discussion.
But we all have our own views on "value" and "worth". As a for instance, a galoot I have a great deal of respect for has a number of Bridge City tools and has explained to me why he sees the value in them. Still, I just can't get there from here. But one of the keys, and I find this to be pretty universal WRT at least one party in all these discussions, is that I don't own any Bridge City tools, and am therefore distinctly non-qualified to pass judgement on their value. Had I owned, used and compared BC tools to my current layout tools, well, now we'd have what I consider to be a valid opinion on relative value as it relates to "worth".