Shiny spots-please help.

[MUAlum2013]

I posted this on Reddit but didn't get much of an answer so decided to come here. Idk what's going on but both my Para 3 BD1N and Lil Native on s45vn seem to get shiny spots so quickly. I decided to get rid of the factory edge and then see (I used a Work Sharp Field Sharpener so 20 on the diamond plates and 25 on ceramic). Both knives razor sharp, burrs removed, and no reflection at all. I literally cut open 1 piece of mail and opened up a salad in a plastic bag. That's it and my s45vn Lil Native has a shiny spot. Just like it did with the factory edge, it's getting these spots so fast. My Para 3, I sharpened it the same way. I cut 1 strip of cardboard probably 8 inches in length and there are 2 spots now. What is going on? I always thought these shiny spots mean that area is dull, flat, or rolled so that's what I'm assuming it means. How can bd1n or especially s45vn get a spot that fast? Before I use it there is nothing. No reflection at all. Then I use it very lightly and its there. Both seem to cut paper just as smooth/buttery with the shiny spot as without it so I'm not sure what's going on. Any one have any ideas? It's so frustrating. I hope I'm overreacting and the spots mean nothing but idk. My d2 qsp Parrot, it took like 2 weeks of everyday use before any shiny spots.

Sorry this is so long. Thanks everyone.

[The Mastiff]

I'd guess the burr isn't gone but still there and making it feel really sharp until use when it folds and does as you see. That is my guess anyways. Good luck.

[sal]

Hi MUAlum,

Welcome to our forum.

Hard to speculate on your question without more "hands on" testing.

sal

[cabfrank]

No expert here, but it has to be a burr or wire edge, doesn't it?

[Fastidiotus]

I always thought these shiny spots mean that area is dull, flat, or rolled so that's what I'm assuming it means.

Both seem to cut paper just as smooth/buttery with the shiny spot as without it so I'm not sure what's going on.

Seems like a flawed hypothesis then. Polished edges and coarse edges both cut, what do you mean by shiny spots? Maybe pictures could help?

Being shiny is the property of a surface having fine enough scratches that light is reflected to your eye in a more consistent linear way instead of being scattered in random directions. Are the things you're cutting leaving finer scratches than your edge finish?

[sal]

I think he means shiny spots when looking a the edge with the light coming from over your shoulder. Usually "shiny spots" are n indication of a dulled spot on the edge of a blade.

sal

[JSumm]

Sounds like what you are doing with the field sharpener by hand should be putting a fairly durable edge on your knives. I agree with the others that it may be a burr issue. Maybe try again with the fine diamond side. Make sure you are hitting the edge and check the edges after. Then skip the ceramic and use the leather strop piece. Alternate sides for each pass on the strop to try an weaken any remaining burr and remove it.

[MUAlum2013]

I think he means shiny spots when looking a the edge with the light coming from over your shoulder. Usually "shiny spots" are n indication of a dulled spot on the edge of a blade.

sal

Yes that's what I meant. So after sharpening I use a flashlight on the edge and zero reflecting. Then after a few light use, there are 2 or 3 spots on the edge that now reflect light.

[MUAlum2013]

Sounds like what you are doing with the field sharpener by hand should be putting a fairly durable edge on your knives. I agree with the others that it may be a burr issue. Maybe try again with the fine diamond side. Make sure you are hitting the edge and check the edges after. Then skip the ceramic and use the leather strop piece. Alternate sides for each pass on the strop to try an weaken any remaining burr and remove it.

I'm going to do as you said and try again. Thank you.

[MUAlum2013]

No expert here, but it has to be a burr or wire edge, doesn't it?

That's what I thought but when I shine a light immediately after sharpening there are no reflections back. I cut a few things and check again with a light and there are now a couple spots that are reflecting. Idk if I'm doing something wrong.

[MUAlum2013]

I always thought these shiny spots mean that area is dull, flat, or rolled so that's what I'm assuming it means.

Both seem to cut paper just as smooth/buttery with the shiny spot as without it so I'm not sure what's going on.

Seems like a flawed hypothesis then. Polished edges and coarse edges both cut, what do you mean by shiny spots? Maybe pictures could help?

Being shiny is the property of a surface having fine enough scratches that light is reflected to your eye in a more consistent linear way instead of being scattered in random directions. Are the things you're cutting leaving finer scratches than your edge finish?

From my understanding, after you sharpen a knife or if the edge has nothing wrong, no light should be reflecting. After I sharpen, I shine a flashlight and nothing is reflecting so I'm like okay thats good but then after I cut a few things/very light work, I shine the flashlight on the edge and now there are a few areas that are reflecting light back.

[JSumm]

No expert here, but it has to be a burr or wire edge, doesn't it?

That's what I thought but when I shine a light immediately after sharpening there are no reflections back. I cut a few things and check again with a light and there are now a couple spots that are reflecting. Idk if I'm doing something wrong.

I actually think this adds to the burr theory. Burrs can be aligned with edge and not as noticeable. Alternating passes on a strop can help eliminate them if you cannot on the plates.

[Notsurewhy]

The others have given solid advice for fixing the immediate issue, so I'll just add:

You may want to pick up a loupe. An inexpensive jewelers loupe can really help diagnose edge weirdness. I saw Sal recommend one a while back, and as always, he knew what he was talking about (that kid is going places, mark my words).

[zhyla]

People always argue with me but burrs are the devil. Avoid causing them and make sure you grind away any that appear.

[Brock O Lee]

Most likely a perfectly aligned burr folding over during the first cuts, like many mentioned in this thread.

I found this booklet about the science of the burr, "Knife Deburring" by Dr. Vadim Kraichuk, very insightful.

Kindle: https://www.amazon.com/gp/product/B07NQ48WG7

A useful test for a burr he mentions, is to push-cut monofilament fishing line perpendicular on a cutting board with a fresh edge. If a shiny spot appears, you have a burr that folded over. A well-formed, burr-free apex would not take any damage with this test.

[jwbnyc]

Running the edge through some bass wood will help with burrs sometimes. Worth a try.

[sal]

Hey Brock O Lee,

Thanx for the link. Ordered.

sal

[Bolster]

A useful test for a burr he mentions, is to push-cut monofilament fishing line perpendicular on a cutting board with a fresh edge. If a shiny spot appears, you have a burr that folded over. A well-formed, burr-free apex would not take any damage with this test.

Neat test. Thanks for that, will use.

[MUAlum2013]

The others have given solid advice for fixing the immediate issue, so I'll just add:

You may want to pick up a loupe. An inexpensive jewelers loupe can really help diagnose edge weirdness. I saw Sal recommend one a while back, and as always, he knew what he was talking about (that kid is going places, mark my words).

I just got 1. Going to check out the edge and see what's going on.

[MUAlum2013]

Most likely a perfectly aligned burr folding over during the first cuts, like many mentioned in this thread.

I found this booklet about the science of the burr, "Knife Deburring" by Dr. Vadim Kraichuk, very insightful.

Kindle: https://www.amazon.com/gp/product/B07NQ48WG7

A useful test for a burr he mentions, is to push-cut monofilament fishing line perpendicular on a cutting board with a fresh edge. If a shiny spot appears, you have a burr that folded over. A well-formed, burr-free apex would not take any damage with this test.

I'm going to check out the booklet and do the test. Thank you!