Burr question

[MrStabby7]

Hey guys I've been sharpening a couple knives using different grit sandpaper. I can see what looks like a burr under magnification but I can just simply wipe it away with a tissue or paper towel. Is this actually a burr? Am I doing somthing wrong here?

 

[chalby]

Hey guys I've been sharpening a couple knives using different grit sandpaper. I can see what looks like a burr under magnification but I can just simply wipe it away with a tissue or paper towel. Is this actually a burr? Am I doing somthing wrong here?

That just sounds like swarf. Most burrs will be too rigid to remove with something soft like paper.

It doesn't sound like you are doing anything wrong. You should be able to feel the burr when you move your thumb or finger down the edge bevel from spine to edge. A small burr will be subtle and may be hard to detect at first, but is what you should be aiming for. A large burr will be very obvious but may impact on the quality of your edge as you refine.

 

[MrStabby7]

I agree its very strange. I wonder if the sand paper is too agressive....not sure whats going on.

 

[000Robert]

The only time that I have seen anything like that was when I was sharpening really cheap steel. The burr would just crumble apart. I've never seen that happen on decent steel with a good heat treat.

 

[chalby]

I agree its very strange. I wonder if the sand paper is too agressive....not sure whats going on.

I wouldn't think sand paper is too aggressive. You can get ultra coarse grit stones that would be equal to any sand paper. If it is multiple knives, I wouldn't think it is bad heat treat or anything.

Not sure what to suggest; are you getting good results, or struggling getting a good edge?

 

[Obsessed with Edges]

AlOx or SiC sandpaper can be extremely aggressive on some steels, which can be a good or bad thing, depending on what you're trying to do. SiC sandpaper in particular can generate some heavy burrs on low-alloy stainless steels at low or moderate hardness (mid-high 50s HRC).

It is possible to create a very wide, but also very thin & fragile burr that'll wipe away with most any contact. So, what you saw might've been a burr, but a very thin & fragile one. When I was using a guided system years ago, I wasn't yet familiar with the concept of the burr. I sharpened way beyond the initial creation of the burr, and didn't notice anything unusual until I lightly dragged my fingertip across the edge and saw a sliver of metal break off onto my fingertip. I thought something was wrong with the steel - but then the lightbulb clicked 'ON' in my head and I realized I was looking at the remains of a very wide and thin burr that'd broken off. Epiphany moment there, and a good lesson learned.

 

[Obsessed with Edges]

Another possibility...

I've noticed that dry sandpaper sharpening can also induce a strong static or magnetic charge in some blades. If that's going on, then the steel swarf created will cling tenaciously to the blade's edge. So that's something to think about. It's a fair possibility you might be seeing some of that. Using a little bit of oil on the sandpaper can minimize that issue.

And a burr will reflect bright light, if it's there. The metal swarf clinging to the edge won't reflect light - it just looks like black/grey dust.

 

[MrStabby7]

Sorry guys, I've been meaning to update this. I hate to say it but I think I was just making a rookie mistake. I had my angle too shallow. What I was seeing under magnification was metal from the bevel but not for the the edge. I adjusted my angle and the knife sharpened up fine. I'm still learning and these traditionals can be tricky. The knife is sharp now so I'm happy.