Thread: Favorite abrasives and surfaces for paddle strops?

For razors I use clean flax and horsehide. For knives I use a 3 x 3 x 12 balsa block. I have white, green and diamond spray as well as one side I glued a piece of veg tanned leather. Balsa is soft I agree. But it keeps you honest. It's easy to see if you are making mistakes. Plus it's easy enough to sand it flat if you dent it. Or if you decide to use some other paste.

I haven’t used pastes much lately for my razors and maybe I should. In the (not too distant) past I have used Kremer pigments (CrOx/FeOx) on balsa with great success. Also CBN on micro fiber cloth attached to a piece of thick glass.

Every time I use diamond I end up hating the edge so I have never really got that one down good.

I have been using CBN emulsion 0.25 micron on glass backed roo. It works very well for me. I've been thinking of adding another of these strops and pasting with CBN emulsion 0.125 micron.

I have a paddle strop with CrOx on balsa on one side and diamond spray on hard felt on the other. Tunes up an edge off a coticule quite nicely if I use the diamond on felt followed by CrOx on balsa. I know that sounds as if I might be walking the edge back using that order, but finishing on diamond leaves the edge a tad harsh IMHO.

I have found that CBN paste on basswood works quite well as long as the basswood is thick enough to avoid warping. I have also used CBN on kangaroo leather and on nanocloth. Either substrates is acceptable.

However, many of the strongest proponents of diamond pastes and sprays prefer balsa. Diamond is a much harsher abrasive than CBN both as diamond is a harder material and the shape of the diamond crystals makes it more aggressive. Balsa has a more open grain structure than basswood. Thus, the diamond crystals get embedded in the grain with only a portion of the diamonds being exposed. That reduces some of the harshness of the diamond abrasive.

Originally Posted by RayClem

I have found that CBN paste on basswood works quite well as long as the basswood is thick enough to avoid warping. I have also used CBN on kangaroo leather and on nanocloth. Either substrates is acceptable.

However, many of the strongest proponents of diamond pastes and sprays prefer balsa. Diamond is a much harsher abrasive than CBN both as diamond is a harder material and the shape of the diamond crystals makes it more aggressive. Balsa has a more open grain structure than basswood. Thus, the diamond crystals get embedded in the grain with only a portion of the diamonds being exposed. That reduces some of the harshness of the diamond abrasive.

Good points on the diamond. I myself always roll my diamond applied surfaces with a steel roller to try and embed them as deeply and securely as possible.

Interesting story of diamond abrasive harshness. Years ago I sold coticule stones and one of my customers was a rabbi who trained Shochets (kosher butchers). They have very strict rules on how an animal is killed for meat and the knife that is used. It must have a perfect edge, no nicks, scratches, flaws or imperfections. It is inspected both before the kill and immediately after. Any flaws found in either inspection and the meat cannot be called kosher. In our discussions of stones and sharpening the topic of diamond abrasives and stropping came up. He explained that he would not use diamond as the angular shape left microscopic scratches on the surface and would violate the Jewish law requiring a perfect edge. The coticule was allowed as the shape of the abrasive was not as harsh and did not leave what they considered scratches.

“Years ago I sold coticule stones and one of my customers was a rabbi who trained Shochets (kosher butchers). They have very strict rules on how an animal is killed for meat and the knife that is used. It must have a perfect edge, no nicks, scratches, flaws or imperfections. It is inspected both before the kill and immediately after. Any flaws found in either inspection and the meat cannot be called kosher.”

That may have been so, just a few years ago. That is not the case now.

There are now, many vendors for Sub Micron diamond paste and sprays, that leave no visible stria, at 400x, (.25 and .10um) rivaling the finish and edge of CBN. Many of these Diamond pastes are very affordable now $15-20 and readily available on the Bay and other sites. Though few razors can handle this edge at this level, but really for a razor one does not need that level to shave well.

It would be interesting to hear from one of the Rabbis who conducts the knife inspections, to see how and what they are looking for. I would also like to know their opinion of a CBN finish on a knife.

Euclid440 The traditional way for them to check is to run the finger nail along the entire edge and feeling for any flaws. While I doubt anyone can feel the difference between a coticule and diamond spray edge with their nail, the idea of it theoretically having scratches was enough for him to not allow their use whether or not they could be seen or felt.


I have long lost touch with him so cannot ask but am curious what their thoughts are now on this subject and whether the sub micron pastes or even CBN can be used. Tradition is a tough thing to break and he seemed very set on certain coticule stones. He tested every stone he bought for performance and inspected them under magnification before agreeing to purchase any. As I recall he had no interest in the Thüringen stones, whether modern or vintage. He taught Shochets from all over the country and would sell them the stones to be used.

I have heard that butchers used Coticules back in the day, but surprisingly it was the natural Belgian Blue side of the stone that they used to sharpen knives for cutting meat.

I have noticed after years of putting high grit edges on my wife’s kitchen knives 12 and 20K, the edges she prefers for meat is a toothy Diamond Plate edge 400-600. I finish her knives on a 1k Diamond plate now.

Vintage natural coticules did/do have some interesting and good performing BBW’s. I remember watching a tv show where a guy, a professional fisherman, was butchering a large fish, tuna or sword fish, and he was describing the process.

He reached in to a well and pulled out a large 8 or 10X3 inch coticule and slapped it on the motor cover, BBW side up and honed a large curved carbon steel filet knife, saying “This is the best stone for sharpening a knife for cutting fish”. Then tossing the stone back into the well with abandon when done. I cringed, thinking, and he’s not even using the best part of the stone.

Originally Posted by Tony Miller

Euclid440 The traditional way for them to check is to run the finger nail along the entire edge and feeling for any flaws. While I doubt anyone can feel the difference between a coticule and diamond spray edge with their nail, the idea of it theoretically having scratches was enough for him to not allow their use whether or not they could be seen or felt.


I have long lost touch with him so cannot ask but am curious what their thoughts are now on this subject and whether the sub micron pastes or even CBN can be used. Tradition is a tough thing to break and he seemed very set on certain coticule stones. He tested every stone he bought for performance and inspected them under magnification before agreeing to purchase any. As I recall he had no interest in the Thüringen stones, whether modern or vintage. He taught Shochets from all over the country and would sell them the stones to be used.

Any idea what is okay to use for lapping kosher coticules? I know there is a prohibition against using them with oil.