my first stropping- found some dark gray compound

[bdmicarta]

I had bought some polishing compound years ago in the local hardware store. I dug it out a few days ago to see what it was and found that it was dark gray "emery" polishing compound.

I have a relatively new DMT Aligner sharpening system. This system comes with rectangular diamond-coated plates so I cut a piece of 1/8" thick balsa to the same size as the plates, glued a thin piece of smooth leather to it, and rubbed on some of the compound. I had previously sharpened my Benchmade 760 with the aligner using coarse, medium and fine stones. The find stone leaves a fairly smooth finish but it has a scratch pattern if you look closely, far from being polished. I did 15-20 or so strokes each side with the new strop attachment and it took away most of the scratch pattern and left a dull polish edge. It also did make the edge sharper. With the DMT Aligner I know that the strop angle will match the angle that the blade was sharpened at. I wonder if a strop angle should be a tiny bit steeper than the sharpening angle. I might try that later on.

 

[Bo T]

There is a lot of give in a strop. I've had better luck using a slightly lower angle. But there are a couple of factors to consider, the softness/hardness of the leather and the amount of pressure on the strop from the blade.

 

[Omega Leather Works]

Sounds like your compound may have silicon carbide in it. I can't speak to its friability, or any others, but I bought some interesting compound a little while back, and at first it had a distinct grit to it. In this case the abrasive is aluminum oxide, but what is interesting to me is that the compound was leaving fine scratches on my mirror polished 1095, but after some use it seems that the AlOx has broken down to a degree.

I wish I had known this before putting my handmade blades to the strop. I would have used knives with lesser quality finishes to break it down since it now seems to keep my blades razor sharp, while at the same time preserving the look on knives that I started using later.

All of this to say- you may consider running over your strop with a junk edge a bit before using it on your good knives.

 

[Obsessed with Edges]

'Emery' is otherwise what would be known as naturally-occurring aluminum oxide (with some other trace minerals in the mix), also called 'corundum'. Most of the commercially available abrasives and compounds made from it are very dark in color, almost black. I have some Ryobi emery compound, and originally assumed it was SiC, based on the color and it's aggressiveness. Not to be confused with 'carborundum', which is the original trademarked name given to silicon carbide, by the inventor of it. Emery/corundum is popular as an abrasive grit, because it's very nearly as hard as silicon carbide, at Moh's ~9 or so; works very aggressively on most steels.


David