We get a lot of questions about strop compounds many of them asking about the difference between them and if they should be using compounds in the first place. So I wanted to answer some of these questions and see if I could provide some insight.
Stropping compounds make it easier and faster to reach a razor sharp edge because the compounds are slightly abrasive. Most compounds are extremely fine with abrasive sizes in the microns. The real difference between each is the type of abrasives. If you want to know which is the coarsest to the most fine the order is Black, White, Green, Red.
|White||Cut and polish||Aluminum Oxide|
|Green||Cut and polish||Chrome Oxide|
|Red||Little cut mostly polish||Ferric Oxide|
If you want to purchase any of these compounds you can do so here.
Any of these compounds can be applied by rubbing them back and forth on the leather. It is similar to coloring with a crayon light pressure back and forth. If you find that the leather isn’t taking the compound you can sand it (the leather) down with some 100 grit sand paper.
Another method to applying the compound is to warm up the strop and compound with a hair dryer. WARNING: DON’T GET IT TOO HOT, THE COMPOUND WILL MELT AND MAKE A MESS ALSO YOU DON’T WANT TO BURN THE LEATHER.
I would like to take is opportunity to both thank you and to help answer some common questions. You didn't simply purchase a product from some vendor, I am the manufacture of this strop and I take great pride in its operation and performance. I really appreciate the fact that you selected my strop and I want my strop to live up to your expectations.
What does stropping do?
After you sharpened a blade using a stone there is a small burr left over and that small burr is the difference between a sharp blade and a razor sharp blade. A blade with a small burr will still slice through a sheet of paper but won’t shave hair like a blade that has been stropped. The main difference between what you are doing when you strop a blade and when you sharpen it is the fact that when you sharpen a blade you remove material. When you strop a blade you are simply realigning it.
Often times you can find the burr with your fingernail by dragging it from the spine towards the cutting edge. I have an over exaggerated picture of a blade with a burr (left) and a blade that has been stropped (right). Below is also a picture of a blade that I purposely added a large burr to, you can see the burr towards the bottom of the blade.
So basically stropping takes a sharp blade and makes is sharper by aligning the edge of the blade.
Basic Knife Anatomy
There's is a lot more to a knives anatomy then you may think (around 14+ distinct points) however I will only cover 3 for stropping purposes. The spine is the back non-cutting structure of the blade, the edge is the cutting edge of the blade and bevel (some knives have 2 bevels) is the part that transitions to the edge.
Basic Knife Edges
There are many different edges out there here are just a few of the common ones. When you sharpen a knife understanding the edge you have is very important. Its less important when you strop however if you don't contact the edge to the strop you wont really be doing anything useful.
How do I strop?
Stropping is accomplished by leading with the spine and pushing in that direction. If you were to push by leading with the edge you would cut the strop. The angle you hold is very forgiving (up to 45 degrees) unlike when you sharpen a blade on a stone. The leather gives and the compound is very fine so if your angle isn't perfect it will still work. With that said I strop much like I sharpen on a stone by following the bevel, on occasion I may use a steeper angle by lifting the spine a bit higher if the edge is a convex edge. Once you are positioned on the bevel just push towards the spine until you reach the end then flip the blade and repeat in the opposite direction back and forth as many times as you wish. If you do it 20 - 50 times and you don't get the results you want the blade wasn't sharp enough when you began.
What Compound should I use?
I get this question a lot. So the answer is it depends on how sharp your blade is prior to stropping. The red is the most rough, with white next, and green is the finest. I will most often use the green as my blades are sharp and kept that way. I also don't mind stropping longer however another method is to use green on one side and another color on the other. This works well as you can start on the rough side and finish on the green. Now remember what I said about sharpening and how it removes material and how a strop does not, well that’s not entirely true if you use compound as it is an abrasive but a very fine abrasive so it will actually polish and remove a small amount of material. The green compound is made from Chromium oxide which is around .5 microns which is about 60,000 grit.
Should I clean the strop?
That's really up to you if you feel like the compound has built up too much then you can scrape it off or sand it down. Also if the leather isn't taking the compound or the surface isn't flat you can sand it down using 80 - 120 grit sand paper.
Once again thank you so much!