Lots of metal buildup on the stones?

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Mar 17, 2011
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Hi all,

I have something happening and I'm not sure if it's normal or not. Nearly as soon as I start sharpening (from a clean, soaked, and lapped stone) ... the entire stone turns gray (I assume from the metal of the knife) and quickly builds up so thick that I need to wipe it off the knife like "mud." My quick, this happens within a minute from starting. Is this normal? Am I doing something wrong?

Oh, and the knifes I'm using are two different Misono UX10s.

What stone are you using? How hard are you pressing on the stone? Do you get that mud with every knife, or one knife in particular?
Sounds like my 1k SS. I'd say it's pretty normal for a soft stone. What stone(s)?
It happens with all three of my stones:
Beston 500x
Bester 1200x
Suehiro Rika 5000x

I may or may not be pressing hard ... I'm new to this so I'm not really sure how hard I'm supposed to be pushing. But it seems to be A LOT of build-up, and as I said, in a really short time. The Bester 1200x which is white will turn solid gray within a minute, and the knife will have a 3D thickness on it, which I wipe off with a towel.

Like tk59 says, sounds fairly normal. Are you raising a burr? How are your edges performing after you've finished sharpening?
I guess a lot of mud means different things to different people but yes, all of these stones make mud although I would say they are fairly average in that respect. You should be happy that it's nice n gray. Be careful with the Beston, unless you damage your edges a lot, you really don't need to spend a ton of time on that one. Also, be generous with the water. If the mud gets too dry it will be a pita and sound like hell. Last, it's not a bad thing to rinse and inspect your edges often.
Also, mud is your friend! Don't wipe it off so much. Once you build up a little mud, if it's thick enough that it's causing you problems, add a few drops of water to the stone with your fingers. This will thin out the mud and keep things even. Do rinse or wipe your knife to check your work and progress, but don't wash the stone off unless you're moving on or otherwise have to do some stone maintenance (lapping for flatness, lapping because the stone has glazed over, etc.).
I use the Beston because I just started, and the knife blades are dull as a round marble ... so I figured I needed to in this case. I assume once I sharpen more frequently, then I can start with the 1200x ... I think that's what you're saying?

Oh and to the other poster, my final product I am pretty happy with (it's able to cut paper, my test) and my wife like's the way it cuts the veggies (her test :)). As to raising a bur, yes! I do it once with the 500x (on both sides) and then again with the 1200x (both sides). By the time I get to the 5000x I can no longer feel anything (should I be at this point?). Then I have some soft fuzzy block and sheet (that I bought from this site) that I rub the blade on when its all done.
You should be feeling progressively smaller burrs as you go up in grit #. By the time you get to 5k, it'll be small, but it should still be there.

I think you talking about the felt deburring block and felt de-burring pad. Take a look at Dave's instructions at http://www.japaneseknifesharpeningstore.com/product-p/stropkit.htm. I'm not sure, but it sounds like you're using them a little differently from the what the instructions indicate.
No expert here, but when my mud begins to get a bit pasty I use a spray bottle and spritz a few time to keep things nice and moist. It's a bit less messy, especially if you are not working over a sink. Disclaimer: I do this because I saw Dave do it in his DVD :cool2:
Make sure the mud is not drying out(it'll create resistence) and not building up too much(causing your edge to skate across the stone). Other than that, mud is your friend.