Pigments for strop compound?

[HuffHK]

Hi all,

I've decided to step up my sharpening and am looking to start doing some stropping. Instead of buying the cheap-o color buffing sticks or expensive diamond sprays I was wondering if I could buy abrasive element in pure form. Specifically I am looking at the following:

Iron Oxide Red
Fe2O3 96 - 97%
Predominant particle size .22 Micron

Chrome Oxide
Content Cr2O3 98.5 – 99.5%
Predominant particle size (μm) approx. 0.3

These are sold as paint pigments and seem to be a lot more economical than getting commercial sprays or compounds. Also it is almost 100% pure rather than some unknown mix/ratio. Anyone use these or similar?

Thanks for any input.

 

[Omega Leather Works]

There are some guys that are very familiar with this sort of thing in the Maintenance & Tinkering forum. HeavyHanded in particular may be able to help. He buys and uses particulate abrasives to make compounds that sell with his sharpening system. I *think* he uses mineral oil for the suspension agent, but can't remember for certain. If you do find a loose abrasive that may work, I'd also consider bees wax as a suspender. I buy compound from a man that makes his own compounds and he won't tell me everything he uses, but I know he uses silicone carbide, and aluminum oxide with bees wax. What else is in there is anyone's guess.

My gut says that the coloring pigments aren't going to work, but I can't say for sure. Might try that chromium oxide as that is usually the most common abrasive in stropping compounds, or I should say, compounds used for stropping.

Also, be safe (ppe=respirator) when working with these fine particulates. I've heard they go airborne readily. Keeping from handling them much before suspension is a good idea.

Honestly, compounds are inexpensive enough to me to not mess with making them. On the other hand I'm a tinkerer to the core so I would never tell you not to try. Just be careful.

Edit- one other consideration... One of the best things about stropping is the shear availability of things to try. There are many different ideas floating around, and the more you test various substrates, the more you find effective stropping surfaces. One of the favorites is to collect the SiC "mud" from the stone you used to sharpen. If you use the stone with min oil, the mud applied to a clean sheet of paper, then wrapped around the stone, works to further refine the edge. I believe that came from Martin (HH) as well, but again I'm struggling to remember atm.

One of my favorite stropping surfaces is (relatively) coarse cardboard. The stiff stuff, like the inside of a cereal box, or kleenex box, is great, but the best I've found is the center tube of a roll of paper towels, cut down the center, then used against the rounded edge of my granite counter tops. Very effective. My only point being that it's easy to find free stropping surfaces. A free sample tile from Home Depot that has a cork face (sanded before use) is another example.
If you do make a compound imo the hardest part is going to be trying to figure out if it's any more effective than something else free. Even the tannins in bare leather can refine an edge to some degree.

 

[Stacy E. Apelt - Bladesmith]

Screened abrasives are readily available from many sources. Be sure to know the screen size of the powder you get. Just because Fe2O3 has a theoretical particle size of .22 micron does not mean that what you get is that fine. It could be in 1/4" pellets and still be chemically pure Fe2O3. Many uses, like paint pigment, have no need for close screening and dedicated particle size, so they are sort of "mill run" grit size.

The best place to get abrasive powders in close tolerances is from a lapidary supplier. They have dozens of types in many grit ranges. Light mineral oil ( AKA Baby Oil) is a good carrier.

When ordering, look at the average particle size as well as the particle size range. Usually, the closer the tolerance, the higher the cost. A $10 bag of abrasive powder will last nearly a lifetime of sharpening, so get good quality and keep it stored in a tightly closed container. Store strops in tightly sealed bags, too. Avoiding contamination with grinding dust and sanding grit is how to keep strops and their abrasives doing their job well.