So, I've had the pleasure of playing with the M2 mule for well over 10 days and it is now time to send it to its maker. I'll try to summarize my thoughts.
TL;DR: It's a decent steel. It is surprisingly rigid and tough for such thin stock, but it is not some hidden gem of edge retention.
As we all know by now, when touting a toothy edge it slices very well. I used the mule in the kitchen for 90% of tasks, primarily as a paring knife.
I noticed straight away that the edge lost its crispness after each use (meaning after preparation of a meal). My primary barometer is the ease of slicing a ripe tomato; it would breeze through a tomato with a fresh edge while making dinner but would take 3-5 swipes to cut through the skin of another tomato when making supper. That's fine, as it still had a good working ede for other cutting. Just not so crispy anymore after one meal prep. Note that I use soft-ish plastic and maple cutting boards.
As for stain resistance: I washed it each night and left it to dry in a rack and it developed some surface rust. I also cut up loads of acidic foods: strawberries, chiles, apples, limes, tomatoes, onions, ad infinitum. A decent patina formed after a few days but honestly, it did not stain or rust as readily as, say, C75, 1075 or 1095.
Fortunately the M2 is easy to touch up. The first time I sharpened it took 10 passes on a medium diamond plate, brown and white ceramic plates, then stropped with green paste on leather. Five minutes of work resulted in a hair popping edge. Subsequent touch ups were done using these:
Next, I cut up a sizable pile of cardboard boxes over the course of two days, cutting up roughly a dozen boxes on each occasion. In case you've forgotten, here's what cardboard looks like when it's cut up (warning: graphic content):
The mule cut through the cardboard very well. As I suspected, the screaming sharp edge vanished quickly. However a decent working edge combined with the thin geometry helped out. After the first few boxes, the cardboard started to bunch up pretty frequently during cuts (see below), but it generally kept cutting well. It did however feel considerably dull after I finished cutting.
I tried to strop the edge back to life after each cardboard session but that really didn't help. I had to resort to my diamond hone and butcher's steel. The good thing about this M2 stuff is that it really takes minimal effort to bring the edge back.
Next, I thought it would be fun to scrape the new, fresh edge against some mild steel to check the toughness. The M2 pulled some decent shavings and, other than being a little duller, the edge held up great and could still cut cardboard. Below: pic #1 shows mild steel shavings stuck to the edge; pic #2 shows the edge after being wiped clean.
It may look like the edge has a bunch of flat spots in pic #2, but that's just my old phone. It really didn't have any dull spots or chips that I could see.
I also tried to dig and pry with the tip. I'm surprised by how little the blade flexed when i tried to pry while refusing to snap, chip, or warp. This thin M2 is remarkably rigid and I'm rather impressed with its stubbornness in surviving the abuse I inflicted.
Now it's got a shaving edge again and is boxed up, waiting on USPS to open up on Monday.
In all, I think it's a good steel on par with any decent carbon steel. I have had better edge retention with 52100, 15N20, and even 1095. I don't think I would ever seek this steel out for any application where I desire edge retention, but I think it would do well in some sort of utilitarian roll where the edge is likely to be frequently scraped against hard materials (like a putty knife or some such). It makes for a decent knife that will work well for general use, but I don't think it's some hidden gem. I would much rather have AEB-L.
Thank you
David Mary
for letting me try out this knife. It was a fun exercise and I appreciate the opportunity.
*also, thank you to anyone who read this entire post. Give yourself a high five, you've earned it.