Sharpening Pastes


Abrasive Compounds 

Starting in the mid to late 1800s, professional barbers were known to tune-up the edges of their straight razors with abrasive compounds on linen and leather strops. 

When I started out using a straight, I started honing them at the same time. That’s a lot to learn, but I like a challenge and a few nicks and little blood didn’t seem all that terrible. My biggest hurdle, it seemed, was getting the edge ‘sharp enough’. That final bit of keenness seemed to be somewhat elusive, so I followed a suggestion and I started using an abrasive paste on a cloth strop to ‘final finish’ my razor’s edge. 

My first foray into this arena brought me to the ubiquitous green .5µm Chromium Oxide paste, and it worked. While “Crox’ solved the lack of sharpness issue, those edges were never ‘smooth’ enough for me. I also felt that using the paste was taking away from the Coticule edge - which makes sense; I was shaving with a Crox edge, not a Coti edge. 

With practice, my Coti edges got better and I was able to use Crox less and less and one day I just tossed it. I suffered though the last bit of the Coticule learning curve, But I never missed that green stuff; it’s my opinion that Crox does not make an edge that is, for me, smooth. Not at all. What other people think about that is fine - I don’t like using Crox. Period. 

But - I was, am, always have been and always will be rather curious, about everything… so I kept trying different pastes out on occasion. I even tried Crox in a few different form-factors - sticks, bars, waxy tubs, etc. In addition, I experimented with many different types of red, black, white, and diamond pastes. These were experiments; I did not intend to find a paste to use regularly. I just wanted to ‘know’ first hand, what people were talking about. Out of all of those trials - only the white crayon paste from Theirs Issard was, in my opinion, a highly useable option; for me, it produced smooth, sharp and efficient edges. 

For a long while - I viewed pastes as a crutch that should be avoided. I’ve since readjusted my thinking here. While they ‘can’ be used as a crutch – that’s not necessarily a bad thing, especially for someone starting out. 

I didn’t, and still do not, consider an edge coming off an abrasive-charged linen strop to be a ‘natural’ edge, regardless of what it was honed on first.  When I view a pasted strop edge under a scope - there’s nothing left of the original fingerprint from the stone before it. Does this matter? Maybe - maybe not. Depends on who’s edges we’re talking about actually. To be honest, I’d rather shave with a well done pasted edge than a half-assed Jnat edge. 

Time for a short detour…. 

Some time ago, I decided to make my own barber hone - a synthetic stone loaded with an abrasive that’s used for quick touchups. After much analysis and comparison, I decided that the Frictionite 00 hone would be the benchmark piece that I wanted to beat. Once I figured out what the abrasive in that hone was, along with it’s particle size and an approximate particle concentration, I started mixing up a few batches of goop and I made a few hones. They were ugly but they worked. I had issues with my rudimentary binders, but they functioned well enough to test with, and eventually - I decided that I wanted a hone that was ‘better than’ not ‘equal to’ the Frictionite. 

Abrasive powders are not a new subject to me. My grandfather was a very well known lapidary, he taught my father how to cut and polish gemstones, and I picked up some of the trade along the way also. We charged many laps with all kinds of abrasive powders for the purpose of polishing precious and semi precious stones. 

So - I got ‘into’ the world of abrasives. I learned some of the lingo and shop-talk, and made a few friends in ‘the business’. In some ways, sharpening steel is different than polishing stones, but in other ways it’s the same. After working and experimenting with some of the powders I was already familiar with, and some I was totally unfamiliar with - I came to a few conclusions - some obvious, others not so obvious. 

1 - particle size is important but it’s not the whole story.

2 – particle size distribution is a huge part of the story.

3 - Paricle concentration is also a huge part of the story.  

4 - the substrate matters, a lot.

5 - pressure matters, a lot.

6 – the edge’s pre-existing condition matters, a lot. .   

7 - particle distribution/concentration concerns are not perfectly linear.  

8 – abrasives on a substrate act differently than when they’re fixed in a binder.

9 – the same abrasive in different binders will yield different results every time.  

10 - most commercial abrasives have a shockingly broad PSD.  

11 – a close-tolerance PSD always beats a broader PSD.  

Ok - back to pastes now…. 

After those, and scores of other, realizations ‘hit home’ - and after a year or two of poking around into all of this, I came up with 3 compounds that struck me as being really quite good for keeping straight razors sharp. By good, I mean that the edges I was experimenting with after finishing on them were keen, smooth, and void of the typical annoying synthetic ‘fingerprint’. Admittedly, these edges are not in the same league as one I’ve I honed on a stone, but still quite good. 

Along the way, I also realized something else - these particular abrasives worked better for me when they were used on a substrate of some sort - usually a linen strop, than when they were impregnated and fixed into one of my binders. 

Realization #4 - “the substrate matters” - it does but that doesn’t mean one is, objectively, better than another. My advice will usually take the form of - “ try stuff - see what works best for you”. Experimenting with different techniques and materials side-by-side will always shed light on the darkness caused by confusion. Abrasives act differently under different levels of pressure. A linen strop will yield a bit, even a light touch, where a hard substrate won’t give. While I do note that most old-skool methods of apply pastes were a strop of some kind, and that was probably for good reasons - I have nothing against using a hard substrate like a balsa block or paddle strop. 

There’s no wrong or right here - only what works best for each person in their home with their gear. I usually test with cotton webbing lying on a piece of wood but I also use hanging cloth strops; I don’t use balsa strops because it’s another ‘thing’ to have hanging around and I have enough clutter here already. I’d put abrasives on a few different types of wood, and it works well. Still, I prefer to use a hanging strop for the abrasives I keep around. I did have quite notable success with using diamond paste on a suede-covered paddle strop though. 

Some people eschew the hanging linen strop for irrational reasons - claiming that doing so will ‘convex the bevel’. Truthfully, every razor’s bevel becomes slightly convex from use, stropping, etc. Theoretically - using an abrasive compound on a hanging strop will convex the edge faster, but I’ve yet to see where this can be quantified accurately. All working edges wear, all working edges need to be sharpened and resharpened. Occasionally, bevels need to be reset. That’s part of the game. 

We use a linen hanger loaded with sub micron paste what - maybe 1x every 10 days to 3 weeks or so? And we put the razor across it for all of maybe 20 passes, or maybe a bit more or less than that. I don’t see this being problematic. If you do believe it’s a problem, no problem - use balsa or whatever… doesn’t matter. All the roads here lead to Rome.   

Back on topic... 

Do note that I’m not endorsing the use of pastes as being a ‘silver bullet’ or a magical cure. Honing on natural stones is fun and I get fantastic results from doing so, and I prefer those results to all other options. 

At the same time, pastes work and they’re fun to mess around with. They’re an acceptable and viable option for anyone looking for a simple, easy to learn, and extremely cost effective method of keeping a good edge on their straight for a very, very, long time. 

It’s irrational to think that everyone is always looking to pull out a hone, make slurry and get knee deep in the process. Given the myriad of personalities out there, it’s plain as day that there’s a need for options and alternate plans in this arena; for example - having a way to effect a quick fix on a ‘not there’ edge or a faster approach to finish come to mind.  

For me, the two most common situations when this need becomes a reality is when I’m traveling or when a blade feels ‘off’ during a shave. For someone starting out, this moment might arise after the first 20-50 attempts to hone a razor. Another person that doesn’t hone at all might find that using pastes is a surefire way to avoid paying out a ton of cash to have someone hone for them all the time. It’s also entirely plausible that there are those who find a paste edge is their favorite over all others. So be it.


© Keith V Johnson 2014 - 2015