Compinds from Harbor Freight

[JWRobinson]

Does anyone know which of the polishing compounds sold at Harbor Freight is finer? I've purchased both the blue and green and they seem to cut about the same but the blue is much harder to load onto the strop. I'm been able to get many of my blades to hair popping sharp by stropping after a little time with a diamond hone but want to see how far I can push "sharp" Aiming for "tree topping" sharp and want to use the finest grit compound I can locally purchase. Thanks in advance.

 

[Obsessed with Edges]

Looking at Harbor Freight's description of each, the blue is described as:

"Multi-shine polishing compound for high-gloss shine on plastics, gold, silver, and die-cast items."

and the green described this way:

"SSX compound achieves a high-polish finish on copper, brass, stainless steel, and steel.

This suggests to me, the blue compound likely isn't very aggressive on steel, regardless of how fine the particle size may be. It's intended for use on soft metals and plastics, so it's probably pretty soft. Might not have much effect at all, on steel. I probably wouldn't bother with the blue compound on a strop.

(Edit: Looking around at other vendors' descriptions of 'blue' compounds, they all seem to suggest it's not a cutting compound at all, on metals. It doesn't abrade metal, so it can't sharpen steel, presumably.)

Green compound is almost always chromium oxide, which is a good polisher for hardened steel, at a (typically) smaller particle size around ~0.5 microns, on average. Use this on the strop; it'll likely do better.

 

[JWRobinson]

Thanks David. I looked at the labels again and you are 100% right about the listed materials. I'm not sure why I was able to get the typical darkening of the strop that had blue compound on it but it might just be dirt rather than metal. The green is working like a champ but I want to experiment with a finer compound after the chromium oxide. Any suggestions? Also, is there a traditional "color coding" of compounds used by most manufacturers?

 

[Obsessed with Edges]

Thanks David. I looked at the labels again and you are 100% right about the listed materials. I'm not sure why I was able to get the typical darkening of the strop that had blue compound on it but it might just be dirt rather than metal. The green is working like a champ but I want to experiment with a finer compound after the chromium oxide. Any suggestions? Also, is there a traditional "color coding" of compounds used by most manufacturers?

The only super-fine compounds I'm aware of (for steel), are the sub-micron diamond and maybe CBN (Cubic Boron Nitride). They will also be more aggressive cutters, as they're both significantly harder than the green compound. Being that they cut more aggressively, it may be hard to predict if they refine the finish beyond the green compound, or not. They can be had in sizes finer than 0.5 micron, but I don't know if they'll perform accordingly.

As for color-coding compounds, I don't know if there's a set standard. I sort of doubt it. Having said that, usually the black will be silicon carbide (extremely wide range of grits, any of which could be black), the red will usually be iron oxide, and green is almost always chromium oxide (and ~0.5 micron average particle size, at least from reputable brands). Most of the time, I think white will be aluminum oxide (again, a very wide range of grit sizes, all of which might be white). There are other 'white' compounds out there, which aren't aluminum oxide, but some other abrasives usually suited for softer metals like jewelry. In fact, there are several colors out there of 'jeweler's rouge', which is normally red ('rouge' is the French word for 'red'). One of the sites I looked to earlier, in reading about the blue compounds, actually referred to it as another form of jeweler's rouge. There are also mixes of compounds on the market, like a mix of chromium oxide + aluminum oxide. That introduces a whole new range of ambiguity.

 

[Bill DeShivs]

If you are darkening the strop, then metal is being abraded.
That said, I would not look to any Chinese product to be consistent or uniform in grit size.
Simichrome polish makes an excellent stropping compound, and is probably available locally.

 

[JWRobinson]

Thanks guys. One of the reasons I love blade forums is the friendly expert advise I get here. I guess I'll get a few known quality compounds from a reputable source so I know what I'm working with and have consistency.