Strop and Strop Compound Question

D

DamnU

Joined
Feb 8, 2011
Messages
127
Hello Everyone,

I would like to start using a strop, but I have a question about the various compounds (Green, Black and White) and the strop itself. In what order are the compounds used? Also, when making your own strop I have heard conflicting theory's about which side of the leather faces the knife, the rough or smooth side?

Any help is appreciated, I searched the forum but I could not find answers to those two questions.
 
Most use the smooth side. Black is coarsest, then green. White is rarely used except on buffing wheels as a final step by knife makers and some factories.
 
This may be rumor, but i heard that some compounds don't go by color. Green can be finer than white and vice-verse. I believe black is usually an emery, white is aluminum oxide and green is chrome oxide. Any confirmation would be nice though.
 
There's a HUGE variety of 'white' compounds out there. Many are aluminum oxide, which itself can come in another HUGE array of grit sizes. Aluminum oxide can also be grey, pink or blue, and maybe other colors. Other 'white' compounds might be completely different stuff, like tin oxide (very soft; made for jewelry and other soft metals). One version of tin oxide is actually referred to as 'white diamond' (confusing enough?). The 'black' compounds will either be silicon carbide or something like emery (a.k.a. 'corundum', which is a naturally-occurring aluminum oxide). And 'corundum' shouldn't be confused with 'carborundum', which is a trade name for synthetically-produced silicon carbide (named 'carborundum' by the original discoverer/inventor). As with the aluminum oxide, silicon carbide 'black' compounds are also available in a very wide array of sizes.

'Green' is almost always chromium oxide (Cr[sub]2[/sub]O[sub]3[/sub]), which is usually pretty fine grit (~1 micron or smaller), down to 'average particle size' of ~0.5 micron, from decent & reputable brands. Some cheaper 'green' compounds might also be a mix of Cr[sub]2[/sub]O[sub]3[/sub] and other compounds, like aluminum oxide, each of varying grit sizes.

It's quite possible that one abrasive of relatively large(ish) particle size might be used for a 'finer' finish than a smaller grit of different abrasive. This is due to the differences in hardness or particle shape, which greatly influence how aggressive they are. Compare diamond to aluminum oxide, for example; diamond will be much more aggressive, in a much smaller particle size.

Clear as mud, right? :)

The best bet, when attempting to figure out a proper sequence of use, is to buy compounds of which the abrasive type (diamond, silicon carbide, aluminum oxide) and particle size in microns are clearly known ('grit' or 'mesh' numbers are often as ambiguous as the color descriptors). If they're not labelled accordingly, ask the vendor. And if the vendor can't/won't say what they are, I'd avoid them. OR, at the very least, spend some time experimenting with what you buy, to figure out how each is going to perform.


David
 
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Thanks for clearing that up David. I'm always trying to differentiate the different grit characteristics. So far, all i've learned is there is no simple answer for any of them
 
If you had to choose between Bark River or Enkay Products, which would it be. I am looking to purchase a black compound and Green compound.
 
fervens said:
Thanks for clearing that up David. I'm always trying to differentiate the different grit characteristics. So far, all i've learned is there is no simple answer for any of them
Click to expand...

That's why I prefer to avoid any of the compounds that don't specify abrasive type or actual particle size. Beyond that, it also simplifies things to stay within a single abrasive type in a grit sequence, such as all diamond, all silicon carbide, etc. And preferably all from one brand. That narrows down the variables, so you don't have to worry too much about other factors like which is harder, particle shape, impurities, etc. Predicting results is much easier that way, if one hasn't yet become accustomed to how the different compounds perform. And results can change yet again, just by varying which steel type you're using the compound on. For example, diamond compound works best on very wear-resistant steels like S30V and D2, but can sometimes be too aggressive on simpler steels like 1095. Conversely, green compound produces quick and very noticeable results on the simpler steels like 1095, but may be disappointing on S30V.

Here's a very detailed thread on abrasive types and some of the different properties affecting how each performs. It's a good read:

Review - properties of abrasives described


David
 
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