ZDP-189 stain removal

[nonfumi]

Longtime Spyderco carrier, but until now I just lurked. Here I’m gonna jump in to see what the experts have to say...
While normally I carry a VG-10 blade, yesterday I happened to have a new ZDP-189 Endura in my pocket. So when a philodendron plant got in my way, I tried my insanely sharp new edge. Very satisfying. I wiped it off, but apparently not enough, because a few hours later the blade had really solid black stains.
Acetone did nothing. WD-40 did nothing. Baking soda plus a lot of elbow grease was fairly effective but there are still some marks.
I get that I could just let patina accumulate, but if I was gonna try to clean this up all the way, what do y’all use on ZDP?
(Add to the list of known ZDP staining materials: mustard, tomatoes, and now philodendron.)

[Wartstein]

"Welcome to the forum" is all I can say, sorry! :o

I do like when my blades start to get "more personal" by scratches, Patina or whatever (really happening on my HAP 40 knives, and my CTS XHP Chap has a small, black spot) so I have not much experience with stain removal...

But I am sure others will know more! :)

[Jazz]

I love how ZDP looks when it stains lightly. Was it bad?

I cut rhubarb with AUS 8, and it stained instantly.

[JMM]

I would bet "Bar-Keepers-Friend" on a damp rag would sort that out in a minute flat. If that doesn't do it, Flitz will.

[kodai78]

I heartily endorse the above suggestion. I don’t have any Flitz but “Bar-Keepers Friend” I got and it works great.

[nonfumi]

Thanks for the feedback. Michael Gallagher at Spyderco also answered my email and recommended Flitz.

The stain was dark black. Like, the same color as the bug logo — really black. Baking soda and elbow grease got most of it but not all. Flitz took out most of the rest of the stain, revealing the pitting (!)

Some lesson with the first day use for a new knife. Gonna have to decide if I let it go full patina, or refinish it to take out the pitting and try to keep it clean.

I read the arguments in older forum posts about whether ZDP is stainless. Did I just happen to find the one thing (philodendron) that does this? Or did everyone decide that ZDP can’t be used for juicy plants etc because lots of other stuff also reacts?

[SteveMidwest]

Welcome to the forums, you philodendron slasher! :D

JMM, has given a perfectly good answer. Bar-Keepers-Friend (In the store, kept near the Comet Cleaner) is a near miracle product.
Flitz is good stuff too.

I don't have a ZDP-189 Endura. I think it has a satin finish, right? Make sure that you do your best when cleaning it, to scrub with the grind lines. With whatever you use.

I will add. If those don't work well enough for you. Is to buy a Klingspor Sandflex Hand Block, Course (FL327518). They are on Amazon for example, for $6.87 right now. It basically a rubber eraser, with a Silicon Carbide (SiC) abrasive mixed into it.

Lastly. When you are done, and happy with your cleaning, finally. Get a small bottle of pure, light, Silicon oil. Rub some of that on, and off, once a week. Depending on how often you use the knife. That will pretty much prevent this from ever happening again.

Have a great week, and enjoy this Forum! :spyder:

[JMM]

I have a Stretch2 in both G10 and FRN, with ZDP-189 and I learned fairly early on that treating it as stainless was not the answer, I live in the Pacific Northwest where it is either Humid, Wet, or Both pretty much year round. I treat ZDP-189 the same way I do any of my tool steel knives (4V, Rex45, K390, etc...) which is to say, wipe all liners down with silicone gun cloth, nano-oil pivot/washers, and a small dot of mineral oil on each side of the blade wiped properly to just leave the lightest of coats on the blade. Doing those 3 things has kept my Tool Steels & ZDP-189 happy & healthy.... hope that helps

[nonfumi]

Those are great answers, thank you.
Down here in South Florida we’ve got lots of fast-growing tropical plants. Lesson learned, I will keep a lesser machete for those, and reserve my nano-coated and oiled high carbon blade for other purposes!

[Wartstein]

I have a Stretch2 in both G10 and FRN, with ZDP-189 and I learned fairly early on that treating it as stainless was not the answer, I live in the Pacific Northwest where it is either Humid, Wet, or Both pretty much year round. I treat ZDP-189 the same way I do any of my tool steel knives (4V, Rex45, K390, etc...) which is to say, wipe all liners down with silicone gun cloth, nano-oil pivot/washers, and a small dot of mineral oil on each side of the blade wiped properly to just leave the lightest of coats on the blade. Doing those 3 things has kept my Tool Steels & ZDP-189 happy & healthy.... hope that helps

Since I never had a real tool steel folder (just fixed blades) may I ask: You actually wipe down the liners with silicone?
Sure the liners are not made of tool steel but stainless, aren´t they? Is it to avoid some reaction between stainless steel liners and tool steel blade?

[TomAiello]

I only wipe down the blade, but I live in desert. No problems so far.

[zuludelta]

I read the arguments in older forum posts about whether ZDP is stainless. Did I just happen to find the one thing (philodendron) that does this? Or did everyone decide that ZDP can’t be used for juicy plants etc because lots of other stuff also reacts?

ZDP-189 is nominally stainless: that is, it's stainless if your qualifier for "stainless" is simply how much total chromium you have in the steel (chromium is the primary contributor to stainlessness in stainless steel). The thing about ZDP-189 though is that so much of that chromium is bound up with carbon (ZDP-189 has a crazy amount of carbon, which accounts for its insane edge holding & high hardness potential) that the chromium doesn't really help with corrosion resistance. Larrin has a chart over at the Knife Steel Nerds website that grades ZDP-189's corrosion resistance at non-stainless tool steel levels, a little lower than 3V and CruWear, and a bit better than D2, M4, K390, and Maxamet.

I've read anecdotal evidence that ZDP-189 reacts particularly bad to acids from citrus and other plants, in that it develops pitting (and not just staining) much more readily than other steels with similar levels of corrosion resistance so that might be what you're seeing in your knife. If I had to speculate, ZDP-189's ultra-high carbon levels probably contribute to this.

I like ZDP-189, my Dragonfly 2 in ZDP-189 cuts for days and days and days (I think I've only had to touch up the edge once over the past 3 years), but I never use it on food or anything even mildly corrosive.

[The Mastiff]

IMO every knife owner / collector should have some Flitz or similar for the occasional use as needed. For me it's just part of my maintenance supplies.

Joe