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SURFACE FINISHES

The surface finish of a stone is the skin of the project and, along with the size and petrographic variety, represents its identity.
Surface finishes are constantly evolving, but the most important ones are:

Flamed Finish:

  • Manufacturing process: Performed on a previously flattened surface to which a thermal lance is applied causing the detachment of small chips or splinters. The process is carried out automatically in special chambers whose main component is a mobile oxy-propane torch which throws a flame at temperatures of about 2500-2800ºC, and with an inclination angle of about 45º. 
  • Resulting surface: The result is a rough surface, with an appearance lightly vitrified.
  • Recommended uses: Particularly, is a superficial finish recommended for all kind of external paving because of, between other things, his behavior from slippage, in wet conditions, is very good. On the contrary, is not especially suitable for his use in interior paving witn intense traffic, because of his roughness doesn´t favor the cleaning and the maintenance.

Bush Hammered Finish:

  • Manufacturing process: Performed on a previously flattened surface, which is repeatedly hit with a hammer with one or more bushes, with small pyramidal teeth. Although it can be done manually, nowadays jackhammers are used which are moved either manually or automatically over the surface of the stone.

Depending on the number and size of the tips of the bushes, the force applied, and the repetitions, the finish may be rougher or smoother.

  • Resulting surface: The result is a flat and rough surface, with small craters.
  • Recommended uses: For the same reason as flamed finish, is a finish recommended for external paving and, on the contrary, not especially suitable for his use in interior paving.

Chipped Finish:

  • Manufacturing process: Performed on a previously flattened surface, generally cut with circular saw, on which elongated, parallel, triangular incisions are made in the same direction, using a pick-axe or chisel. It is usually done by hand, but can be done with a power tool equipped with steel teeth.
  • Resulting surface: The resulting surface is very rough and has a rustic look. The notches or elongated incisions give it a somewhat coarse appearance.
  • Recommended uses: this type of finish is normally used in quarry stone for facades, as can be seen in many old buildings; it is also suitable for outdoor paving with a rustic appearance provided it does not involve any inconvenience to pedestrian traffic.

Sandblasted or Shotblasted Finish:

  • Manufacturing process: Sandblasting is achieved by blasting the surface of the stone with silica sand or corundum, driven through a nozzle by air at high speed and with variable pressure. When steel shot is used, the finish is called Shotblasted. Depending on the pressure applied and the flow of abrasive, a finer or coarser finish is obtained.
  • Resulting surface: The surface treated presents evenness, with several small orifices, smaller than the result obtained with bush hammer dressed. The depth of the orifices could change as the pressure of the air exerted and the grading of the sand projected.
  • Recommended uses: Any use in external and interior of the buildings, although is not especially recommended in interior paving, for his rough surface.

Flagstone or Split or Natural Finish:

  • Manufacturing process: In rocks with schistosity planes and marked foliation such as slates, it is generally done by hand using flat chisels, sometimes called “guillos” or wedges. These are used to open the stone at the sedimentation or schistosity planes.

In other types of massive, non-slaty rocks, the finish is performed either by hand or using hydraulic machines, which split the material along the mineral orientation planes.

  • Resulting surface: as the surface of the stone is not worked, it presents a natural, irregular but fairly flat appearance. In some rocks, such as slates, the odd “step” usually appears due to breakage of the schistosity planes.
  • Recommended uses: Facades and interior and exterior vertical finishes. Outdoor paving in areas without excessive traffic. This finish is usually used for making rustic paverstones and parts for walls.

Sawn/Cut Finish:

  • Manufacturing process: This finish is achieved by cutting the pieces using steel or diamond strips, diamond wire or diamond disc. It is usually a process prior to subsequent surface treatments, but can also be used as a final finish.
  • Resulting surface: Provided a smooth surface but something rough and matt with a few diffused aspect. When it is realized with a disc, the surface could fit with lightly grooves.
  • Recommended uses: Every use inside and outside buildings although not specially recommended for interior paving due to his rough surface.

Grooved/Ribbed Finish:

  • Manufacturing process: Using a cutting machine, a series of parallel grooves are machined in order to increase the resistance to slipping in the direction orthogonal to the latter. The width of these grooves is defined according to the desired look.
  • Resulting surface: The resulting finish is a surface with parallel grooves, which are arranged in a direction orthogonal to the traffic.
  • Recommended uses: Outdoor paving in areas of pavements recessed for pedestrian crossings.

Brushed or Aged Finish:

  • Manufacturing process: Starting with a flat or rough surface, the stone is attacked by friction using brushes with metallic or diamond bristles.
  • Resulting surface: It is obtained a rough satin surface, with soft touch, that no presents significant difficulties for the cleaning of the paving. This kind of finish constitutes a special case at the time of interpretate the results of the roughness, because superficial beaks are rounded due to the treatment.
  • Recommended uses: Interior and external pavings, in this case, always we ckeck his grade of slipperiness.

Honed or Ground Finish:

  • Manufacturing process: This treatment is applied to compact rocks with minimum hardness. It is achieved using rotating, abrasive wheels of varying grain size, with a sequence set according to the desired roughness. These wheels are usually silicon carbide and are manufactured under the name of the grain size of the abrasive that comprises them, according to the FEPA (Federation of European Producers of Abrasives) classification. In some areas, when the grain size is FEPA 60, the treatment is called grinding. It is a similar process to polishing but without achieving the shine.
  • Resulting surface: Provided a smooth and matt surface.
  • Recommended uses: Paving and interior covering. Slabs for external facades.

Polished Finish:

  • Manufacturing process: Used in rocks with a higher degree of crystallinity, such as granite and marble. In the same way as the honed finish, polishing is achieved by a sequence of rotating abrasive wheels, from higher to lower grain size, applied to the surface to be treated. The finer wheels are those that give the material a glossy finish.
  • Resulting surface: Result of the surface: The surface obtained is smooth and brilliant, with an invalid porosity which gives to the stone a better resistance to attack of external agents.
  • Recommended uses: Interior paving and covering.

Other finishes with chemicals:
Today, in addition to the aforementioned mechanical finishes, there are a number of products that can vary the performance and aesthetics of stone products. These are multifunctional chemicals which, when applied to the natural stone surface, can improve its qualities. 
Some examples of this or protective resins, anti-slip products, anti-graffiti products, etc.

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