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Helderberg

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Dec 8, 2013
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Has anyone ever stripped the coating off a tool steel blade, M4, M2, and if so what have you done to protect it from rust?
Thanks in advance, Frank.
 
I've owned tool steel blades with no coating to begin with. The trick to protecting them is to due your basic maintenance on them. Make sure you don't soak them in water or allow water to dry on them, keep the blades clean, so when you cut something wipe the blade off so you do not allow corrosive material a chance to eat at the steel, and oil. There are hundreds of oils, lubes, waxes, and polishes available and they all do the similar type thing. Another thing is, don't keep blades in leather sheathes for storage.
You would do the same thing to a rifle, shotgun, handgun, or even some hand tools. Another thing that confuses people is that they think the blade coating will inhibit rust on a carbon blade completely. It will to some extent but not 100%, you still need to maintain your tools.
 
I stripped the BK coating off my 710D2 when it failed. The coating's bonded to the steel even so and provides some protection even now, but with a wipedown and thorough drying between uses I haven't seen anything to worry me. One trick; every once in awhile I'll remove the studs just to make sure it's clean on both sides.

 
Revdevil, this is good information. I have many tools that are exposed to water everyday as a plumber, and I simply wipe them down, keep them oiled and clean. I have been reading the posts concerning the tool steel blades and what some have described as "rusting easily" and it made me concerned as I know nothing about the high end steels. I imagine my Estwing hammer is a good steel and I have never worried about it rusting. Thank you for the clear and concise answer, I will be keeping my Contego and enjoying it.
 
I have quite a few Spyderco CPM-M4 blades (same material) with no coating and I've had no troubles at all, with just a little care. If you use the knife around water (especially salt water) or in high humidity conditions, you may want to consider using something to keep corrosion down. Bear in mind, though, that stainless steel knife blades are for the most part a relatively recent development, and everyone got along just fine with carbon steel tools and blades.
 
I sanded a Benchmade 525M4 blade down thru the coating and grind lines till I had a perfectly flat plane, then ran thru the grits to a 3000-grit near-polish. I learned as I worked on the blade that M4 will tarnish visibly w/ just specks of water left for a few minutes.

Took the knife outside and did a little pruning, smearing plant saps of course on the blade. W/in 15 minutes of exposure I had the sap cleaned off the blade w/ Goof-Off, but noticed that under the sap smears there was already corrosion. One of the nice things about sanding perfectly flat to 3000 is that the blade can be easily refreshed w/ 3000-- did that quickly, removing the corrosion (or so I thought). Oiled the blade, happened to catch a light reflection w/ distorted colors (light reflecting on oiled remaining corrosion like a rainbow)-- so I took this picture:

100_7771_2.jpg


I've played w/ contrast/sharpness etc on the above pix to more-clearly show the depth of the corrosion (which I then sanded off completely, but it was deeper than I ever would've imagined given such short exposure).

90 minutes in fresh lemon juice (7% acidity) gave the blade a nice greyish cast:

100_7797.jpg


Could be patina'd much darker. Water is unavoidable, but I'll try to stay away from other corrosives w/ M4.
 
Helderberg said:
Revdevil, this is good information. I have many tools that are exposed to water everyday as a plumber, and I simply wipe them down, keep them oiled and clean. I have been reading the posts concerning the tool steel blades and what some have described as "rusting easily" and it made me concerned as I know nothing about the high end steels. I imagine my Estwing hammer is a good steel and I have never worried about it rusting. Thank you for the clear and concise answer, I will be keeping my Contego and enjoying it.
Click to expand...
Oh let me tell you, even in the dry Arizona desert I've had carbon steel pliers, adjustable wrenches, and ball peen hammers rust in a matter of days. I never could explain it to this day. I started using the WD-40 spray to remove water from my ratchets, vice grips, etc. As it displaces water, it does great. Heck, I even use it on folders when I wash them out with soapy water. The trick is to remember to use something like Ren Wax or Flitz to clean up the blade. It works and even removes some tiny scratches without giving you a super shine. Although you can polish up a blade, I don't like the looks myself.
 
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