How-To and Why -

Not unlike several other aspects of straight razor use, the process of razor sharpening has benefited by the application of modern processes and materials. This article will attempt to explain the use and benefits of today’s modern Diamond Sharpening Pastes and how their use as part of your razor sharpening regimen can vastly improve the quality of your razor’s cutting edge, thereby improving the comfort and closeness of the shave.

Razor sharpening pastes have been around for many years. The most commonly used pastes employed a fine powder of either iron oxide, chromium oxide or graphite as the cutting agent, suspended in a carrier paste, which was then spread onto a leather or wood surface and used as a strop to finish the edge. It was not unusual to see a bundle of strops hanging in some corner of the barber shop, each dedicated to a different type or coarseness of sharpening paste. The use of sharpening pastes is similar to the use of hones in that you begin with a coarser grit to accomplish the greatest amount of work in the shortest time, and move on to progressively finer pastes to further refine the edge, ending in a finely polished, mirror-like finish. Where this process began to break down is when advances in metallurgy resulted in ever-harder steels used to make the blades, and the compounds used as cutting agents in the sharpening pastes became ineffective because they were actually softer than the blade they were expected to sharpen. What actually resulted was that by using a sharpening paste with a cutting compound softer than the blade material was, the blade became duller, rather than sharper! All of this changed with the development of Diamond Sharpening Compound.

Diamonds are the hardest substance known to man – far harder than any steel yet developed. Industrial grade diamonds, though similar in hardness to gemstone quality diamonds, are typically the by-product of the diamond mining industry. Their quality is inferior only due to flaws, color inconsistencies, or other characteristics that render them unsuitable for jewelry. Also, in the process of cutting and polishing gemstones significant waste is produced. These are the diamonds that become abrasives. When crushed to a fine powder they form perfectly irregular edges that serve ideally as cutting edges and being harder than any other substance they hold those edges longer than any other material. This diamond powder is what does the actual work of sharpening.

It is important to point out that all diamond compounds are not equal. The best compounds are very carefully controlled in their manufacture to assure consistency in the size of the actual diamond particles. For example, a compound that is classified as “one micron” though it may have particles smaller should contain no diamond particles larger than one micron. This is an important consideration, especially in a close tolerance application such as producing a highly refined razor edge.

Another area of differentiation between compounds is the basis of the carrier paste. In an industrial polishing application an oil-based paste, (typically a petrochemical) may be acceptable. For use in sharpening a straight razor a water-based paste is preferable as the paste will easily rinse away after sharpening and is unlikely to cause any skin irritation or infection.

One caution that should be addressed when discussing the use of diamond compounds for razor sharpening is degree. It is possible for a razor edge to actually be too sharp, and this could easily result by over sharpening with diamond pastes. A razor edge that is too sharp will catch on every surface imperfection in the skin causing irritation and razor burn. To achieve a close yet comfortable shave the razor’s edge should glide over the skin, barely touching, and only catching on the base of the hairs it is intended to cut. Generally, using a diamond compound finer than .50 micron can result in an over-sharpened edge.

In most cases, one micron or smaller diamond sharpening pastes are more than capable of sharpening a razor which has become dull through normal use. By starting with an even coarser grit - in the one to ten micron range, depending on how dull the beginning edge is, you can refine the "not quite shave-ready" edge typically found on a new, out-of-the-box razor. Before sharpening a new razor you should first try shaving with it. If it pulls, drags, or is in any way uncomfortable, sharpening is required. By testing it before sharpening you can evaluate how close to shave-ready it is and use this information to guide you in how much sharpening to do. Generally, 20 round trips on each side of the diamond pasted strop will get it right. If after sharpening and again trying to shave it needs more work, repeat the process. Though you may have heard of many different ways to test the sharpness of a razor - the hanging hair test, the standing hair test, shaving your forearm, etc., the only true test is actually shaving with it.

In most cases, a good paddle strop or two and several different grit diamond sharpening compounds will be all that is needed to maintain a fleet of daily shavers. What diamond pastes will not efficiently do is establish a basic working edge on a razor that hasn’t seen a hone or strop in 50 years, or work out a ding or chip that is the result of dropping the razor or some other accident. For this type of work only a hone will do. However, once a hone has been used to do the heavy work, diamond sharpening pastes will refine the basic edge quicker and in a much more controlled manner than any hone can.

Now Let’s Go To Work –

The best tool to use with your diamond sharpening pastes is a paddle strop. A surface of either soft wood, such as balsa, or leather is preferable. The important thing is that the surface be sufficiently rough or grainy as to hold the paste. If the surface is too smooth or hard the paste will simply be wiped off with each pass of the blade. This is not only wasteful (and expensive) but is ineffective. The paste should be applied to the surface in very small amounts, usually about the size of a pea. For a typically sized paddle strop 2-3 pea-sized dots evenly spaced along the length of the strop is sufficient. These dots should be thoroughly worked into the surface using the fingertips or the heel of the hand. The more time spent working the paste into the surface, the more effective the sharpening action will be. You will also find that with successive uses the effectiveness of the cutting action will be improved as the surface becomes more built-up with abrasive. Toward this end, do not clean off the surface after use. When the effectiveness seems to have diminished simply apply a small amount of fresh paste, work it in and continue.

As with all sharpening pastes, a surface coated with a particular grit of paste should now be dedicated to that grit only. While it is possible to increase in grit size, you cannot decrease. A surface once used for .50 micron may subsequently be used with 1.0 micron, but you cannot do the reverse.

To maintain a fleet of regularly used razors, typically a two-step process beginning with 1.0 micron, followed by .50 micron will achieve a perfectly smooth shaving edge. Be sure to completely wipe off the blade when moving from the coarser grit to the finer, and again before moving on to your un-pasted finishing strop to prevent cross-contamination.

The motion used on the diamond pasted surface is identical to that employed on your hanging strop – working from the blade’s heel to the point as you travel up or down the surface, leading with the razor’s back, and applying no pressure – using only the weight of the razor to maintain constant contact between the razor edge and the pasted surface. After having sharpened your razor you should finish on the un-pasted leather strop, omitting use of the canvas or linen side. Your razor is now ready to use. Routine use of the canvas/leather pre-shave stropping may be resumed for successive daily shaves.

This procedure, used every 2-3 weeks, should be all that is necessary to keep your razors in perfect shaving condition.