Vivi's M4 Manix XL DLC Corrosion Log

[Cambertree]

I've used M4 in the past and I always appreciated how easily it sharpened for the level of toughness and edge holding it offers. It always struck me as a well balanced steel that offers everything in spades aside from corrosion resistance, obviously. Takes a very keen edge every time I sharpen it.

As for how it performs on my Manix I can't make much of a comment beyond the factory edge. It came screaming sharp, one of the top 5 sharpest factory edges I have ever used. It came with a more polished edge than Spyderco typically runs, feeling perfectly smooth when I run my thumbnail along the apex. It has held that sharpness well the past week. I stropped it 3x per side today with my 7 micron diamond paste and its a little sharper than when new. Pops hairs effortlessly and push cuts receipts.

Despite my love for coarse edges, I have to say this more polished edge has cut things very well, even things more polished edges can struggle with. It just goes toshow that a cleanly apexed knife will be able to simply cut, period. I can slice cooked sausages and thick poly rope no problem with this knife, and I can shave with my 300 grit edges formed off a $12 diamond stone. You don't need a super coarse edge to cut rope (though it will keep cutting rope longer), and you don't need to go above 200-400 grit for shaving sharpness or push cutting paper.

Good stuff, Vivi.

Yeah, I agree, M4’s a really satisfying steel to use and sharpen. That’s interesting you’ve been using the factory edge. Pretty much all the Golden edges I’ve had have been very good, but I’ve heard that they even seem to be improving lately. I haven’t purchased a Golden knife for a while, but the Seki K390 DF2 edge was also outstanding for a production knife.

It might be interesting to check out the stained DLC areas with magnification, as your experiment progresses.

[curlyhairedboy]

That permanent staining from the latest update is what I'd see on DLC m4 after 2 carries in summer pockets. Still way better than red rust/pitting, though.

I know barkeepers friend will take the spots off.

[vivi]

That permanent staining from the latest update is what I'd see on DLC m4 after 2 carries in summer pockets. Still way better than red rust/pitting, though.

I know barkeepers friend will take the spots off.

I plan to gradually step up my cleaning process after another week of keeping things the same. I'll keep carrying it outside of work and trying to stay as active as I can, and do the thumb cleaning at the end of the day.

Next weekend I think I'll go at the blade with hot soapy water and a microfiber towel. If that doesn't clean it I have BKF and magic erasers I can try.

Have you used BKF on DLC? I know DLC is very hard but I'd be a bit worried about the abrasive nature of BKF breaking it down some.

[JRinFL]

Vivi, no offense meant, but I fully expected this to fully rusted by now based on previous posts. Great thread, BTW.

[JRinFL]

That permanent staining from the latest update is what I'd see on DLC m4 after 2 carries in summer pockets. Still way better than red rust/pitting, though.

I know barkeepers friend will take the spots off.

I plan to gradually step up my cleaning process after another week of keeping things the same. I'll keep carrying it outside of work and trying to stay as active as I can, and do the thumb cleaning at the end of the day.

Next weekend I think I'll go at the blade with hot soapy water and a microfiber towel. If that doesn't clean it I have BKF and magic erasers I can try.

Have you used BKF on DLC? I know DLC is very hard but I'd be a bit worried about the abrasive nature of BKF breaking it down some.

BKF is a mild acid, so I would avoid on a tool steel if it were mine. I usually just use a synthetic oil or mineral oil and a microfiber cloth for my cleaning of blades.

[curlyhairedboy]

That permanent staining from the latest update is what I'd see on DLC m4 after 2 carries in summer pockets. Still way better than red rust/pitting, though.

I know barkeepers friend will take the spots off.

I plan to gradually step up my cleaning process after another week of keeping things the same. I'll keep carrying it outside of work and trying to stay as active as I can, and do the thumb cleaning at the end of the day.

Next weekend I think I'll go at the blade with hot soapy water and a microfiber towel. If that doesn't clean it I have BKF and magic erasers I can try.

Have you used BKF on DLC? I know DLC is very hard but I'd be a bit worried about the abrasive nature of BKF breaking it down some.

So far the DLC has held up very well, I use the liquid barkeepers friend and only scrub a little with a droplet on my finger for a few seconds, then rinse well. I believe it's the oxalic acid that does the brunt of the work.

[SpyderGrill]

I must have Vivi blood. Painting a garage floor in a hot and swetty pocket in SW Florida my Delica VG-10 had a few spots on it.

Following this thread for results.

[Sumdumguy]

Could it be remotely possible that the corrosion on the DLC was perhaps metallic residue from the manufacturing process that was somehow embedded on/in the DLC?

I don’t know. Kinda like when some people report rust forming on the “H1” etching on the H1 Salt blades (which is without a doubt leftover residue from the tooling process). Just throwing that out there.

Jim

Possibly.

For what its worth there's no corrosion (yet) on the two exposed metallic surfaces of the knife.

I have found that uncoated M4 is surprisingly corrosion resistant. Not saying it won't rust, just that it's not that crazy. Mine has a few very light pitting spots and a patina that is almost impossible to photograph.

The blade on my old Rex45 PM2, matched the handle within 2 hours on the job. I've never had that issue with my Mantra and it has been carried a great deal more than the former, just mineral oil and go.

It's one of my top three favorite steels.

[vivi]

October 16th update.

Carried the Manix a few times since the last update.

As I mentioned, this week I tried more intensive cleaning procedures.

I soaked the blade in hot soapy water for five minutes. Then scrubbed it with an old toothbrush. Wiped it dry with a microfiber cloth.

Here it is from two angles, one trying to show the spots as well as I could, another trying to hide them with poor lighting:




Wow. Dramatic difference. Almost completely clean.

I still have Flitz, Bar Keepers Friend and magic erasers I can try as well.




Interesting side note, this is the first spotting I've encounter on the edge. Not concerned with that at all as I plan to reprofile it this weekend.

[kobold]

Is it possible that, since DLC is porous, when you thumb clean you are actually rubbing the salt crystals into those 'pores', thus promoting corrosion. Maybe the best approach would be to treat the blade weekly with oil, to saturate the DLC layer and only use water to quickly rinse the blade and wipe it gently with something dry and absorbent. So ultimately, maybe just leaving the salt crystals where they are (on the surface of the DLC) is better than thumb-cleaning it.

The permanent solution might be to use a 'drying oil' such as boiled linseed oil or tung oil which are used to protect wood from moisture. These oils will, after hardening, stay in the DLC, just like they do in the 'pores' of wood. Best to apply 3-4 layers.

Maybe treat just one side of the blade and then you would have a control..

[vivi]

Is it possible that, since DLC is porous, when you thumb clean you are actually rubbing the salt crystals into those 'pores', thus promoting corrosion. Maybe the best approach would be to treat the blade weekly with oil, to saturate the DLC layer and only use water to quickly rinse the blade and wipe it gently with something dry and absorbent. So ultimately, maybe just leaving the salt crystals where they are (on the surface of the DLC) is better than thumb-cleaning it.

The permanent solution might be to use a 'drying oil' such as boiled linseed oil or tung oil which are used to protect wood from moisture. These oils will, after hardening, stay in the DLC, just like they do in the 'pores' of wood. Best to apply 3-4 layers.

Maybe treat just one side of the blade and then you would have a control..

Long term that might be the best plan for inhibiting corrosion, but my goal here isn't to keep the M4 blade corrosion free. Its to test my theory that DLC significantly improves corrosion resistance.

My experiences with the S30V DLC Manix XL led me to believe I wouldn't need to use oil. The whole point of intentionally exposing the M4 Manix to corrosive fluids repeatedly it to get an idea of how much DLC makes a difference in respect to corrosion resistance.

Remember, I basically treated the S30V DLC Manix like a Salt, and never saw any corrosion or spotting on the blade.

While the M4 XL hasn't performed quite to that level with the degree of spotting I've seen, I'm still very impressed at how its cleaned up with mere soapy water.

The level of spotting I've seen on this knife would have been just as bad with uncoated VG10 or S30V. Uncoated M4 would not have cleaned up this well with these methods.

So while I had hopes for less spotting, I'm still convinced corrosion resistance is superior than it would be on uncoated M4 at this point.

[kobold]

:o Yes, sorry. I saw a knife in distress and the instincts kicked in. :)

[vivi]

October 20th update.



Carried IWB on an 80F day during 7 miles of hiking in a mellow mountain range, then prepped some dinner.



Here's how it looked at the end of the day:



Later, I tried to clean it real well.

I soaked the blade it hot soapy water for one minute, then scrubbed it with a toothbrush. Then I soaked it in hot soapy water for another minute, and used a magic eraser. Then I dried the blade completely. Here's the result.



At this point I feel comfortable in my claim that DLC increases corrosion resistance.

[Cycletroll]

Good stuff Vivi!

[The Meat man]

Hey Vivi, have you at any point during the testing oiled the blade?

[vivi]

Hey Vivi, have you at any point during the testing oiled the blade?

No.

[vivi]

October 23rd update



Lookin pretty clean for a carbon steel blade intentionally exposed to corrosive fluids for a few weeks.

[TkoK83Spy]

Looks just like my Para 3 version of the same knife I've been carrying all week (and many times before) that's never cut any foods or corrosive things. Strictly warehouse type materials.

I have to agree with your DLC claims, and obvious visual proof from the outside.

[vivi]

October 27th update.

Started the day with my C95 in my pocket, but switched to the XL before heading out for a round of disc golf at a steep mountain course.




Curiously this is the first time I recall seeing rust near the laser etching.

Second picture is after wiping it off with a dry t-shirt.

The lines streaking across the blade in the first picture is residue from slicing up a bunch of cardboard this afternoon. It isn't corrosion.

Tempted to repeat this test with an uncoated M4 XL.....

[Wartstein]

Interesting thread, Vivi...

I perhaps should start a similar one about my (of course uncoated) REX 45 Manix LW - the very first Spyderco I seem to be able to corrode myself, at least a bit :p
(But for that it takes cutting all kinds of food, IWB carry, letting it sit in wet pockets or packs for quite some time and so on..)