There was a time when the only serious file to buy was Nicholson, but even that company has bowed to the "profit above all" mindset. Meaning that they have "cheapened" the materials and methods used in their files in order to realize as much profit margin as possible. The ONLY Nicholson file that I still consider "good" are the one's marked with "Black Diamond". They are harder and harder to find, and tend to be about 1/3 more expensive then the standard Nicholson files. Several years ago I had one of those analyzed, and the results were identical to 1095, with the exception of carbon content.....that came back as 1.27%. That doesn't mean the material hasn't changed, as companies are constantly seeking ways to reduce production costs, and increase bottom line profits.
In general, expect just about any/every file that can be commercially obtained to be case hardened material..... unless you can prove it otherwise. About 2 years ago I was wondering through Home Depot....and noticed that the Husky brand files were marked with "Lifetime Warranty". This got me to thinking, and I went to the service desk, and asked about the warranty..... to include "Does the warranty cover the files wearing out?" The answer I got was "If you are not satisfied, for any reason, return them with the receipt, and we will replace them." I purchased two sets of the following:
https://www.homedepot.com/p/Husky-Multi-Purpose-File-Set-10-Piece-H10PCFS/206313272 Since then, I have returned/replaced a total of 12 sets under the warranty. I simply cut a slot in the packaging, and store the receipt there, so I can find it when I need to return/replace. I've had some folks who question me doing this, saying that I am taking advantage, but in my mind, if the labeling states "Lifetime Warranty", then that's exactly what it should be.
