Delica 4 K390 blade has scratch on the letter area, what’s the cause?

[Kou]

Delica is the first Spyderco I owned, love the compactness and ergo. But I noticed the blade developed a pretty noticeable scratch mark near the Spyderco letter and I wonder what the cause is. Is it the liner? I tried to sand down the inner edge of the frn scale and the liner edge on the show side but still noticed the scratch developing over time after I buffed it out with Flitz. How to fix?
Pics: https://imgur.com/a/BSuYfWG

[sal]

Hi Kou,

Welcome to our forum.

sal

[Kou]

Hi Kou,

Welcome to our forum.

sal

Thank you for greeting me Sal! I love my sharp spydies!

[USMC-88]

Pic’s please

[JFR1]

I could be mistaken, but that looks like corrosion, likely from close contact between the blade and the liner in the closed position. Scratching from the liners/scales is normally axial, like an arc, not a straight line.

[benben]

Will it rub off? Kind of looks like corrosion to me also.

[Kou]

I could be mistaken, but that looks like corrosion, likely from close contact between the blade and the liner in the closed position. Scratching from the liners/scales is normally axial, like an arc, not a straight line.

Oh Corrosion might be it. That explains why after I sand down the scale and liner but only made it worse. More room for moisture to be trapped in there I assume? The back side is completely fine tho no corrosion

[RustyIron]

But I noticed the blade developed a pretty noticeable scratch mark near the Spyderco letter and I wonder what the cause is.

This is an easy one. The cause is corrosion where dirt and moisture accumulate. I just got out all my own K390 knives: a Delica, two Police, and two Enduras. They all show this phenomenon to varying degrees. On my Delica, the line is in exactly the same place as yours, although mine isn't as pronounced and the edges are fuzzier.

Close the knife, and you'll notice that your "line" is just below the edge of the handle. Gunk gets in there when the knife is closed. Where the metal is exposed, the gunk gets wiped off by the fabric of your pants and you don't get corrosion.

How to fix it? If the knife is a user, I wouldn't get too excited about it. K390 reacts with lots of things in the environment. If you want blade that sharpens up nicely and holds that edge, K390 is great. If you want a blade that sparkles like Kylie Jenner's smile, you might be happier with some kind of stainless.

If you want to get rid of the line, you might get a pice of emery cloth, maybe 600 grit or so, and tape it down to a FLAT surface. Take your blade and hold ONLY the ricasso perfectly FLAT against the emery cloth. Rub the blade at EXACTLY the same angle as the original grind marks. Change to a different grit emery cloth if that's what's needed to match the original. You can do the same thing with emery cloth wrapped around your finger, but it's a little harder maintaining parallel lines and not wrecking the lettering.

[Jeb]

K390 is really bad about corrosion, so you really need to treat it like a firearm and oil it down... least here in the Texas heat we do and I just edc something else during the really hot sweaty months.

I got a couple of K390 Police4 's that I had one get so bad over the period of one night I couldn't clean the rust off of it, no matter what I did or how much I rag wheel buffed it with compound.

Really bites too with how good K390 really is far as edge retention and toughness. Its corrosion resistance is nonexistent...

It's the same thing I have seen for stainless gun barrels too. We can really good barrels with great profiled rifling that is sharp and basically perfect in every way, but we have to really watch them and keep them oiled.

[Wartstein]

K390 is really bad about corrosion, so you really need to treat it like a firearm and oil it down... least here in the Texas heat we do and I just edc something else during the really hot sweaty months.

I got a couple of K390 Police4 's that I had one get so bad over the period of one night I couldn't clean the rust off of it, no matter what I did or how much I rag wheel buffed it with compound.

Really bites too with how good K390 really is far as edge retention and toughness. Its corrosion resistance is nonexistent...

It's the same thing I have seen for stainless gun barrels too. We can really good barrels with great profiled rifling that is sharp and basically perfect in every way, but we have to really watch them and keep them oiled.

As always when reading posts like this one I almost can´t believe it (to be clear: Just expressing my astonishment, of course I do believe you! )

Like it is with other non-stainless steels K390 just does not show any signs of corrosion in my use so far, not even a slight patina. Despite me using my K390 Endela SE for food prep (and all kinds of stuff, like moist wood) without cleaning the blade immediately afterwards, carrying it iwb on sweaty runs, or on long, rainy days in wet/moist pockets/packs, ... (it also does not show "the line" on the ricasso we´re talking about here)

I still have not figured out why this is... must have to do with different "sweat chemistry" or how "salty" the precipitation is in the area one happens to live... ?

Anyway: I´ve learned to be very reluctant when people ask how corrosive a certain steel might be, cause coming only from my own experience I´d often say "don´t worry", while many others here in fact do have corrosion issues with the very same steel.

[Doc Dan]

Brasso or Flitz will probably take it off. After that, wipe the blade down with Vaseline and then wipe off all of excess. You don't want it gunky. Vaseline in paraffin wax and mineral oil. It won't come off when you wipe it down to remove the excess. it will leave a fine coat. Problem solved. It is food safe, too.

[Palestrina]

Same here, I love it - looks pretty cool to me.

[sv4]

Delica is the first Spyderco I owned, love the compactness and ergo. But I noticed the blade developed a pretty noticeable scratch mark near the Spyderco letter and I wonder what the cause is. Is it the liner? I tried to sand down the inner edge of the frn scale and the liner edge on the show side but still noticed the scratch developing over time after I buffed it out with Flitz. How to fix?
Pics: https://imgur.com/a/BSuYfWG

Corrosion. Not long ago I bought a new in box Endura K390 from the local dealer. Our climate is hot & humid all year round. There was a line like that too, where the blade met the scale. It wiped off easily.