Polished or flamed: which one for outdoor paving?
Flamed, for anything outdoors at ground level. Polished granite turns slick as soon as it is wet and is effectively unusable after rain. Flamed is rough and slip-resistant and is the default for exterior paving. Keep polished for facades, worktops and interior floors.
Why is polished wrong for exterior floors?
Polished is a ground mirror finish. Water forms a film on it and friction drops close to zero, whether from rain, washing or condensation. Anti-slip grooves help only marginally, because the problem is the flatness of the surface itself, not the absence of grooves.
How is a flamed finish produced?
A high-temperature flame is passed quickly across the slab and the surface crystals fracture, leaving a rough, granular face. The process alters the top few millimetres, so the same block finished polished and flamed will not be the same colour: flamed reads lighter and more matte.
Does a flamed surface hold dirt?
Yes. A rough face traps dust and mud, and pale stone greys off over time. The trade-off is that it cleans easily: one pass with a pressure washer brings it back. Dark flamed stone stays presentable longer and needs less maintenance than pale.
Can flamed be used indoors?
It can, commonly at entrances, garages and indoor-outdoor transitions. Be careful where people walk barefoot, because the texture is abrasive and does not mop clean. Where children or elderly people are present, a honed or bush-hammered finish sits more comfortably between the two.
Can one wall use both finishes?
Yes, and it is common: polished on the elevation for depth, flamed at ground level for grip. The catch is that the two finishes differ in colour, so place the transition at a string course or under a coping. Put it in the middle of the visual field and the colour break becomes the first thing anyone notices.