Question about sharpening and burn marks

[American1776]

This is a question for experts on steel and sharpening.

One thing I’ve noticed, with Spyderco and other high end companies, is that it’s common for the edges (especially the tip of the blade) to come from the factory sharpening with a discoloration—usually dark or light orange, but sometimes black—from overheating during sharpening.

The picture attached is from a different company from Spyderco, but I’ve got Spydercos with the same issue.

This particular knife is 154cm, just came back from the factory, and I specifically asked that the sharpener avoid overheating the tip. You can clearly see the orange tip. This from a company whose knives are 275 dollars plus.

Is this only cosmetic, or does it adversely affect the integrity of the tip?

I’d like to hear your thoughts on this. Thanks!

[yablanowitz]

According to one of the Spydercrew from manufacturing I spoke with a few years ago, that would be enough to make a Golden, CO knife a factory second. That was before the robot sharpener was on-line, which sharpens under a coolant at all times. As for the actual effect on the blade, it would depend a lot on the steel involved. Most people would not notice any difference. Hard to be certain with nothing for scale, but it looks to me like a couple of hand sharpening would remove the affected area.

[zhyla]

Is this only cosmetic, or does it adversely affect the integrity of the tip?

This is a good sign that you should be concerned the temper has been blown, softening the steel. It could be just surface level but on a tip, unlikely.

Tips are difficult, they don’t have as much heat dissipation. Honestly if I knew Spyderco is doing resharpening by hand on a grinder I would never trust them with sharpening a knife.

[American1776]

Thanks for the feedback.
This is not a Spyderco pictured, but an Emerson Persian that I sent in to Emerson for sharpening.

I specifically asked that extra care be taken to avoid overheating the edge / tip, and this was the end product.

I’ve had Spyderco knives come back from the factory burnt at the tip as well (a matriarch and a Civilian).

It’s a shame because these are companies who really should know their own craft well.

To be fair, I’ve been told that 154cm is a steel designed for aircraft engine fan props, so it’s supposed to retain its molecular structure at very high temperatures.

I also a a Pat Crawford custom titanium knife come with a burnt (and soft) tip. So it seems to be an issue even with expert professionals.