Pasted stropping - finest abrasives

**snafuspyramid** · 14th February 2013, 01:16 PM

So, I've been dabbling in the dark arts of straight razor shaving. There's a surprising lack of transferable knowledge from WW sharpening. However, I've come across the following possibly interesting insights regarding the abrasives used to paste razor strops.

First, few use the Veritas green polishing compound. It is only between 30-40% chromium oxide, the rest is aluminium oxide. While it is possible to screen aluminium oxide to sub 0.5 micron grits, the molecules will clump together and behave as if the abrasive is much courser. In any case, according to the manufacturer, neither oxide was screened to eliminate particles above 10 microns (or something similar, can't remember exactly).

It is for this reason that you can actually see distinctive, fine scratches after using the compound on a chisel. If the grit were really a uniform sub one micron they would be completely invisible to the naked eye.

Not that there is anything wrong with the Veritas compound, at all. If it really were so fine, you would take forever to get a decent edge with it. WW tools do not need the same degree of sharpness as razors.

Nonetheless, for the true sharpening weirdo such as myself, pure chromium oxide is called for. An exceptionally pure and uniform example is the German-made Kremer #44200 Green pigment, available online from this website: AP Fitzpatrick Fine Art Materials Shop, Paints & Pigments, London.

A yet finer edge can be obtained with the sub 0.1 micron #48100 iron oxide, another common component of automotive polishes. There would obviously be no point doing this with a woodworking tool, however. I also can't find a supplier.

What think ye?

**Robson Valley** · 14th February 2013, 04:19 PM

I read that the iron and copper oxides have nominal (love that word) particle sizes of 0.25 - 0.5 micron. You might do better, if you need straight chrome green, to buy a tube of artists' chrome green paint. Check the Color Index and the composition = should be quite clean.
Better yet, the magnetic properties of iron oxide particles are fantastic below 0.1 micron. You want a fine edge? Fire up an old-fashioned 6mm reel-to-reel tape deck, with a 16.5cm spool, on fast forward, and hone your razor like never before.

Now, a diamond knife for electron microscopy is or was $1,500/mm edge. To get a knife resharpened was $1,500/mm edge. You don't see scratches at 60,000X.
= = =
All I care about is the quality of the edge in my wood carvings. Glassy cuts and I don't care how it got done. With all my crooked knives, I go from 1,500 grit auto paper to the strop with chrome green for a useful edge.

**Ben Dono** · 15th February 2013, 07:30 PM

Hey Eddie, have you tried the kremer pigment yet?

**JPA** · 16th February 2013, 03:51 PM

I think if you sharpened with the 0.1 micron iron oxide, it would last but one chisel strike

.

Having said that, I'm just about to abrasive strop my straight with some 0.1 micron Kremer Pigments #48100. I'll let you know how it goes! I have only a teaspoon that came with my razor but if you go here: Kremer Pigments Inc. and search for "48100" it should come up. Don't know if they would ship here though.

**snafuspyramid** · 16th February 2013, 10:16 PM

I don't think I would bother with the 0.1 micron on the razor, let alone on a chisel.

I do think that the 0.5 micron might make an interesting progression from my 10k Naniwa.

Pointless for practical purposes, of course.

**JPA** · 16th February 2013, 11:11 PM

I've read that 0.3 micron is comparable to a 12k stone. But of course some stones have different ratings when the grit count is so high.

I'm only using the 0.1 micron because I was told it can extend the life of the edge between full honing, which I'm yet to undertake.

It is interesting to think about though - abrasives so high and stropping realign the very edge of the steel...I can't really comprehend what that means

.

**Robson Valley** · 17th February 2013, 08:28 AM

There are three different grit-grading systems. American, European and Japanese.
Pity that they all don't just implode and we actually measure nominal particle sizes instead. Honing compounds seem to be going that way.

As soft woods like Western Red Cedar are prone to show carving tool edge defects more readily than a harder wood, 0.5 micron chromium oxide honing compound works just fine. Nevertheless, within 30 minutes it's easy to feel that the tool is just harder to push.

**Berlin** · 22nd February 2013, 11:41 PM

I have a pot of synthetic iron oxide pigment from Schmincke that I tried for kicks as a honing compound. It was amazingly effective. I only go to 8000 on a waterstone so it may not be better than just going to the next stone...

The pot only cost me 8 euros though (11 bucks or so) and I have honing compound for two life times.

Cheers

**Ben Dono** · 24th February 2013, 08:37 AM

Years ago I tried out normal red cement oxide which I guessed at the time was a synthetic iron oxide. I cant say I had any luck with it but that was a long time ago and I was new to stropping... I'm going to give it another go now Berlin!

**Berlin** · 25th February 2013, 10:47 AM

Originally Posted by Ben Dono

Years ago I tried out normal red cement oxide which I guessed at the time was a synthetic iron oxide. I cant say I had any luck with it but that was a long time ago and I was new to stropping... I'm going to give it another go now Berlin!

Yeah, give it a whirl. I'd be interested to know how it works for you. Just get the best brand of pigment you can, I've seen Schmincke and Sennelier here, both are very good. It's expensive paint but cheap honing grit, for sure.
Cheers

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