Guides · Technical
Which edge profile should a stone top have?
In short. The edge profile is not a decorative detail: it is where a stone top breaks first. Here are the profiles that actually exist, why a sharp arris chips, and which edge survives everyday use.
Why is the edge the weak point of a stone top?
Stone takes compression extremely well and tension and shear far less well. In the middle of a top that limit never shows, because the load spreads across the surface and into the support underneath. At the edge it does show: that is where the material stops, and an impact is absorbed by a very small quantity of stone.
A sharp arris takes the argument to its extreme. The apex where the two faces meet has, in effect, no cross-section: there is no material beneath the point that gets struck. And the edge is also what an impact reaches first, every time: a pan set down badly, a plate that slides, a cupboard door, the shoulder of someone walking past. It is not bad luck that almost every chip is there.
The remedy is as old as the trade and is called arrising. The sharp line is taken off with a micro-bevel, and in place of a fragile apex there are two obtuse corners that an impact struggles to break away. On a polished top that micro-bevel is of the order of a millimetre or less: a thread of light, invisible from a metre away, that changes the fate of the piece. On stone that will be walked on, where impacts are of another kind, the chamfer grows to two or three millimetres.
Which edge profiles actually exist?
Beneath the trade names, which change from workshop to workshop, there are only a few families.
The square edge is the ninety-degree cut, polished on the face: the most neutral profile, and the one contemporary architecture asks for most often. It is made either with a light bevel on both arrises or left sharp, and the difference between the two versions is entirely a matter of how long it lasts.
The demi-bullnose rounds the top arris only and leaves the rest of the edge straight: it takes the sharpness away where the impacts land without changing how the profile reads. The full bullnose rounds the whole edge on a full radius and is the most robust profile of all, because it has no arris to break away. The ogee is a shaped convex profile with a return beneath it, more drawn than a bullnose and classical in feel.
The mitered edge is not a profile but a construction: the front of the slab is cut at forty-five degrees and a strip of the same material, cut to the matching angle, is bonded underneath, so the top looks far thicker than it is.
Which edge forgives everyday use?
In order, from the most forgiving to the most delicate: full bullnose, demi-bullnose, ogee, square edge with a bevel, square edge left sharp, mitered edge. This is not a ranking of taste but of geometry: the more material gathered around the point of impact, the less likely a chip is to start.
There is a second factor, though, discussed far less often: how the edge was finished. An edge that comes off the CNC and ships as it is stays microscopically ragged, and those irregularities are the initiation points chips start from. An edge gone over by hand lasts longer at the same profile, and quotations almost never mention that step.
The mitered edge: why it is wanted and why it deserves respect
Because it solves a real problem: commercial slabs are thin compared with what many projects picture a stone top to be. A miter gives a far greater apparent thickness without the weight and cost of solid stone: from a two-centimetre slab it is common to reach a front showing seven to fifteen.
The price is that the top arris, where the two cut faces meet, is the most exposed point on the whole top: two thin feathered edges converging on a glue line. In softer materials, marble included, that cut calls for a sharp blade and a slow feed rate, and the one thing that really protects the arris is an easing pass after cutting. Where that pass is missing, the chip often arrives before delivery does.
Bonding is the other half of the work: two-part resin pigmented to the background colour of the stone, clamped until it holds and left a full day before the piece is handled. The same principle governs the seams of a long top: the colour of the adhesive decides whether the line is seen.
How do you recognise a well-made edge?
With a finger, before the eyes. The arris must not cut: if the fingertip feels it bite, the easing was never done. On a mitered edge the hand must meet no step between the slab and the strip below it, and the glue line must be no wider than a credit card, which is less than a millimetre.
Then with the eyes, but along the edge rather than face on: the eased band must be the same width over the whole length, and the polish on the edge must match the polish on the face. An edge duller than the top is an edge finished in a hurry, and it will age differently. On what changes between polished, honed and brushed, which finish to give a marble top.
Does the material change the answer?
It does. Quartzites, hard and compact, hold even a hairline arris well. Marbles and soft stones call for finer grits, because a coarse abrasive overshoots the intended width in an instant. Coarse-grained granites want a slightly wider bevel, or the crystals pluck out instead of cutting. Layered stones such as slate flake if they are worked by hand: there the chamfer is cut with a router.
Which is why the edge should not be chosen from a catalogue of profiles but on the slab that has been chosen. The profile that holds on a quartzite is not automatically the right profile for a soft, strongly veined marble: one more reason why picking the slab comes before everything else.
Does the setting change the edge?
A dining table is the case where the edge is touched most: forearms rest on it for hours, and a sharp arris that would merely be fragile on an island is uncomfortable here as well. A worktop takes heavy, concentrated impacts, and the demi-bullnose is the prudent choice. Around an undermount sink cut-out the edge should always be softened. On thickness and overhangs, how thick a marble top should be.
On hotel and project work the criterion shifts again: the right edge is the one that can be repeated identically across dozens of pieces and, if one piece ever has to be replaced, remade the same without argument. A complicated profile is beautiful once and difficult a hundred times.
If a chip arrives anyway, and on a top used every day it eventually does, it can almost always be repaired without replacing anything. A well-chosen edge pushes that moment much further out.
How we work
We saw and work the slabs in our own factory, and the edge profile is decided with the slab in front of us, together with the finish: a polished edge on a honed top is noticed, and the other way round.
Stoneform and Brianform are two divisions of one company, with production in house: between whoever draws the piece and whoever works it there is no commercial step. It is why the edge is something you discuss rather than something you pick from a catalogue.
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Frequently asked questions
Which edge chips least?
The full bullnose, because it has no arris, and then the demi-bullnose. The most exposed is the mitered edge, because of the two thin faces meeting at the top arris.
Can I have a genuinely sharp arris, with no rounding at all?
Yes, and it is a frequent request in contemporary projects, but it is worth accepting a micro-bevel of less than a millimetre: it cannot be seen, it does not change the drawing, and it removes the cutting edge. An absolutely sharp arris on a soft marble is a chip postponed.
Is a mitered edge weaker than solid thickness?
On the surface no, because the slab is the same. At the arris yes: a solid piece has neither a glue line nor two converging feathered faces. Done properly it holds perfectly well; done in a hurry it is the first thing to give.
Does the edge change the price of the top?
It does, because it changes the working time: a square edge with a bevel is one pass, a bullnose takes several, a mitered edge is a cut, a bond, a clamping and a final pass. The difference is not in the material, it is in the hours.
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The points on arrising and micro-bevels, the dimensions quoted and the behaviour of different stones under abrasive are drawn from the technical documentation of manufacturers of stoneworking tooling. The figures on the mitered edge — cutting angle, pigmented two-part resin, clamping and curing times, achievable apparent thicknesses — come from trade manuals on edge profiles. The profile names follow the usage of Italian marble workshops. None of this replaces the written terms of an individual order.