Sharpening Systems Compared: Real Entry Costs and Upkeep (No Made-Up Numbers)
Sharpening Systems Compared: Real Entry Costs and Upkeep (No Made-Up Numbers) - A step into the workshop.
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The frozen ground has barely softened here in Vermont, but the shop is warm enough to work, and the question on the bench this month is the one that comes around every few years: what do you actually spend to keep an edge? Not what feels nice in the hand, not what a magazine cover promises. What does it cost to buy in, and what does it ask of you afterward? I set out to compare four common systems — diamond plates, waterstones, oil stones, and sandpaper on glass — on entry cost, maintenance, and the edge they leave on an A2 chisel. What follows is what the sources actually support, and where the honest answer is that the evidence runs out before the question does.
Four Systems, Four Kinds of Work
A bench stone, broadly, is a slab about three inches wide, eight long, and an inch thick, running somewhere between forty and two hundred dollars, with cutting material of ceramic, diamond, or aluminum oxide. Canadian Woodworking puts the full-size category in exactly that range and notes that some stones are double-sided, a different grit on each face. That is the wide gate through which all four systems pass, and from there the paths divide sharply.
Diamond plates are, as A.G. Russell describes them, roughly four layers of industrial-grade diamond dust embedded in metal. You use only the weight of the blade as pressure — lean on it and you strip the diamond — and most need no lubricant at all, running dry. Petroleum-based oil is off-limits unless the maker says otherwise.
Waterstones are soaked or splashed with water. Canadian Woodworking says some must soak up to thirty minutes; A.G. Russell says usually about an hour. The disagreement matters only in that you should plan for the longer figure and be pleasantly surprised by the shorter.
Oil stones take honing oil slathered across the surface, and here is the one irreversible fact in the whole comparison: a stone used with oil cannot be converted back to a water stone. Choose once.
Sandpaper on glass — the "scary sharp" method — is abrasive film or paper peeled onto a flat plate. 3M's microfinishing film, sold by Workshop Heaven, comes in aluminum oxide or silicon carbide on polyester with pressure-sensitive adhesive, explicitly for scary sharpening and for flattening plane soles, and it sticks to any flat plate or glass surface.
What the Ticket Says
Entry costs, taken strictly from what I could verify and attributed where it belongs. Sharpo's Scary Sharp glass-plate kits start at $29.99 for the Pro, with the Pro XL at $45.99 and the Pro Diamond at $89.99 — though that last listing shows a regular price below its sale price, so treat that one number with suspicion. A silicon-carbide waterstone flattening stone listed at Sawinery runs $29.90, and was sold out when I looked.
On the high end sits the DMT Dia-Flat lapping plate from Sharpening Supplies: ten by four inches, 120-micron monocrystalline diamond, machined flat to within five ten-thousandths of an inch, each unit hand-tested, at $199.99, marked down from $244.79.
For waterstones and diamond bench stones, my only clean prices are European. Knivesandtools lists the Shapton Pro 1000 at €44.99 and the Shapton Glass Stone HR 1000 at €40.49. The same retailer lists a DMT DiaSharp eight-by-three extra-extra-fine bench stone at €155.99. These are EU prices in euros with VAT included; they are not US retail, and I will not pretend otherwise. Oil stones appear from around €11–14 for SK11 stones up to €28.36 excluding VAT for a SUN TIGER 150 mm in 320 grit.
One cost cuts across all four. The Veritas Mk.II honing guide, from Fine Tools, runs €71.90 for the Standard and €159.90 for the Deluxe, with three angle ranges — 25°–54°, 15°–40°, and a 10°–20° back-bevel setting — and it holds blades 13 to 72 mm wide and up to 13 mm thick.
The Maintenance Each One Asks
Here is where the four systems genuinely separate, and where the verified material is strongest.
Waterstones wear. Wikipedia states it plainly: whetstones wear away with use, typically in the middle, and a tool sharpened in that groove develops an undesirable curve until the stone is levelled with sandpaper or a flattening stone. A dished stone must be flattened — Canadian Woodworking says with another stone or an abrasive on a flat surface — and many stones will break if dropped. That flattening stone at Sawinery is the tool for the job.
Diamond plates hold their flatness because only a thin coating of grit wears. Wikipedia says so, and A.G. Russell says a properly treated diamond stone will last years or even decades, and needs no flattening. But the sources conflict on whether diamond wears at all: Knivesandtools claims diamond stones do not wear down and can serve as levelling stones, while Wikipedia and A.G. Russell both say plates do eventually wear out and need replacing, with lifespan extended by light pressure. The conservative reading is slow wear, not zero.
Oil stones take their oil and keep it. No conversion back. Beyond that, the verified sources are quiet on oil-stone maintenance in any quantified way.
Sandpaper on glass is peel-and-replace. The film wears, you strip it, you stick down a new sheet. No flattening, no soaking, no oil.
The A2 Question, and Where the Evidence Stops
I wanted to end with a flatness verdict on the same A2 chisel across all four systems. I cannot give you one, and I will not dress up a guess as a test.
What is verified about A2 is only this: Lie-Nielsen's A2 blades are cryogenically treated, hardened to Rockwell 60–62, double tempered, ground top, back, and edge, and the maker recommends honing a secondary bevel of 5°–10° to improve performance and edge life in hardwoods. That is a starting specification, not a comparison.
No source I could reach measured flatness retention or edge quality on an A2 chisel across these four systems. No head-to-head sharpening test opened successfully. And the flatness discussion in the verified material concerns the flatness of the stone, not the flatness of the chisel — which is a real distinction, because a dished waterstone curves an edge regardless of the steel, while a diamond plate stays flat but demands light pressure or you strip its grit. The honest position is that flatness follows from the stone's condition and your pressure, not from a brand.
The same wall blocks the cost-per-year question. No source computed a three-year total for any system, and no verified figure exists for sandpaper sheets per year, waterstone replacement interval, oil consumption, or diamond plate lifespan in sharpenings. I can tell you what each system costs to enter and what it asks of you in upkeep. I cannot tell you what it costs to run for three years without inventing numbers, and inventing them would be worse than saying so.
What I'd Tell You at the Bench
If I were setting someone up tomorrow, I would start with the sandpaper-on-glass kit — Sharpo's Pro at $29.99 is the cheapest honest entry I found — and put the real money into a good honing guide, because the Veritas does the work that separates a sharp edge from a ruined one. Add a diamond plate when the paper starts to feel like a chore, and expect it to wear slowly rather than never. Choose oil or water once, and know that the oil choice is permanent.
The measurements the editor wanted — three-year cost, the A2 flatness test — are the right questions, and the research simply did not answer them. Until someone runs that test honestly, I will trust the stone's condition and my own light pressure over any claim that one system keeps a chisel flat. The snick of a well-honed edge tells you more than a spec sheet.