Granite slabs and tiles for heavy traffic

Where granite goes and marble should not

The useful test is not geological. Ask four things about the surface: what lands on it, how often something is dragged across it, whether anything acidic is part of the daily routine, and whether it is wet while it is being walked on. Granite is the answer as soon as more than one of those comes back yes.

That puts granite on stair treads, where a nosing takes point loading at the same edge hundreds of times a day. It puts granite on kitchen worktops, where citrus, vinegar and descaler are ordinary use and a calcareous stone would carry a dull etched ring within weeks. It puts granite on entrance thresholds and lobby floors, where the abrasive is grit carried in on shoes rather than anything spilled, and on external paving, where sun, rain and vehicle load all arrive together.

Marble is not disqualified from any of those by hardness alone. It is disqualified by what it is made of and by how visible the damage is once it starts. A honed marble threshold in a house survives. The same threshold in a shopping centre does not, and the difference is footfall multiplied by grit rather than the stone being weak.

Treads

Point load at the nosing

Worktops

Acid contact, daily

Thresholds

Grit, not spillage

Paving

Sun, rain, vehicle load

Flamed, honed and polished

Flaming passes a high temperature flame across the sawn face. The crystals at the surface expand and spall off, and what is left is an open, slightly rippled texture a hand can read. Grip is the best of the three by a wide margin, wet or dry. The trade is that the colour goes pale and matte and the crystal grain loses most of its contrast, so a flamed granite reads as a tone and a texture rather than as a pattern.

Honing grinds the face flat and stops before any gloss. The grain reads clearly and at close to true colour, with no reflection over it. Grip sits between flamed and polished, which makes honed the usual answer for an internal floor that is walked on dry.

Polishing takes the face to full gloss. The crystals darken and saturate, the speckle reads at maximum contrast and depth, and the surface throws a reflection. It is the most slippery of the three under water and the quickest to show a scratch, so it belongs on vertical surfaces, worktops and dry interiors rather than on anything that gets rained on.

Flamed

Open texture, best grip

Honed

Flat matte, true colour

Polished

Full gloss, least grip

Acid, stain and the calcareous comparison

Marble, travertine and limestone are calcium carbonate. An acid meets them and reacts, and the reaction leaves a dull mark etched into the surface that no amount of cleaning lifts, because material has gone. Lemon juice, vinegar, wine, cola, a limescale remover and most bathroom cleaners all do it.

Granite is a silicate. The same spills sit on the surface and wipe off. That is the single practical reason granite ends up on kitchen worktops and calcareous stone does not, and it is worth stating plainly, because hardness usually gets the credit that chemistry has earned.

Granite is not immune to everything. It is porous enough that oil will darken an unsealed slab and stay there, and a dark even granite shows a repeated oil mark more readily than a busy speckled one does. A penetrating sealer on installation and a neutral pH cleaner afterwards covers it. Abrasive pads and bleach are as unwelcome here as they are on marble.

Slab, tile and cutting to size

AFINISHES manufactures concrete tile and supplies natural stone. Granite is bought in, and the work carried out at the Karachi works is the sawing, calibrating, finishing, edging and cutting to size. None of that is quarrying, and it is worth being clear about which end of the process we own.

A worktop is a slab question. It comes out of one piece so the grain runs through, the sink and hob cut outs are made from your drawing, and the front edge is profiled, usually mitred so the stone reads thicker than the slab behind it. Send overall dimensions, cut out positions and the direction you want the grain to run.

A floor is a tile question. Tiles are calibrated to a common thickness so the bed lies even and the joints stay flush, which matters more on granite than on a softer stone, because a proud edge on a hard tile is the first thing a shoe finds. Granite is slow to cut, so a settled cut list before the saw starts is worth more here than on any other material we handle.

Worktop

Slab, cut outs to drawing

Floor

Calibrated tile

Edges

Square, eased, bevelled, mitred

Granite outside, in Karachi

Outside in this city a paving stone deals with long hours of direct sun, salt in the air near the coast, and a monsoon that leaves standing water on it for days. Granite takes all three, which is why it turns up on drives, thresholds, steps and terrace paving where a softer stone would be picking up damage inside a season.

Specify flamed for anything walked on outdoors. The open texture is what holds grip when the surface is wet, and the pale matte face runs cooler underfoot in sun than the same granite polished. Keep polished for a wall, a cill or a sign face where nobody stands.

Where the requirement is a driveway rather than a stone terrace, compare the concrete paving units we cast ourselves. Those are made to a vehicle load rating rather than selected in the hope of one, and the format, the colour and the laying pattern are settled at the mould instead of at the saw.

Outdoors

Flamed

Vertical

Honed or polished

Driveway

Compare cast concrete paving