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 Slates and Sandstones (Natural Stone Products)
These are mined and cut to size. Natural stones, slates and sandstones come out of the ground and are 100% natural. No two tiles or colours will be identical. Depending on the density of the stone in question (e.g. granites are much harder than marbles, slates, travertines and sandstones) sealants may again have to be applied (although optional) as these tiles vary in degrees of porosity.
Since these products have been exposed to the elements and created from soils, earth and chemical mixes, they are suitable for indoor and outdoor use.
Sandstone/slate may vary in thickness and no current batch will be the same as the previous consignments. A professional tiler will be required to lay these products as the skill levels required will be higher than those of standard thickness ceramic or porcelain tiles.
Slate and sandstones will not have a homogenous flat surface as these products are layered and are split manually from blocks/slabs taken out of the ground.
Slates are not suitable near salt water or where the water salt content is high(salt water pools, seaside). Soluble salt will be absorbed into the layers of slate - the water will evaporate leaving a build up of crystals behind, resulting in tiles eventually delaminating in layers.
 
 Grading or Classification of Products
First Grade(applicable to ceramics and porcelain) must conform to E.N. specifications (European Norms, which combine the German DIN standards, British BS standards and French UPEC standards). These standards govern the parameters of water absorption, size variation tolerances, measure of hardness scale, resistance to thermal shock, crazing and chemical attack, abrasion levels and frost resistance.
Commercial Grade - often referred to as Run of the Kiln. This normally comprises 75-80% first grade product and 20-25% second grade product (mixed in the same box), the latter having some defects or off-standard quality problems, such as size variation beyond the 0.5% in which case the grouting joints will need to be slightly wider. The hardness of glaze is exactly as per first grade product as production processes are identical. Only when sorting the tiles one will find some visible defects or blemishes. Commercial grades/ROKs are sold with a 15-20% cost saving. This cost saving is in lieu of labour having to separate the firsts from the seconds from the production run. A manufacturer knows that from production to production they produce a certain percentage first grade, say 75%, then 20% seconds and 5% thirds/rejects. The rejects are discarded and he is left with approx. 80% firsts and 20% seconds as a mix in one box. Commercial grade is not to be confused with Commercial Applications/Areas. It is strictly a quality term in this instance.

 
 Clay Tiles (Extruded or Pressed)
Often loosely referred to as Terra Cotta (meaning Earth Fired). These are generally used in outdoor and indoor applications. They can be glazed but are generally produced as a rustic, slip-resistant floor covering. They are also generally more susceptible to staining and somewhat more difficult to maintain..
These tiles have been used for hundreds of years (before current levels of technology) in Cape Dutch type homesteads, old farmhouses and the like.
It is not a uniformly perfect product as norms allow for greater tolerances (i.e. 1% size variation of the nominal size, plus water absorption varying from 3% to as much as 12%).
Treatment or sealant application will vary depending on the degree of porosity. No one sealant or application will make the product impervious to stains., Sealants vary from wax based products, to silicones, to urethanes and resins, oils, epoxies and cellulose based products. Each sealant has its own properties and method of application (should you wish to seal the tiles). Some sealants will enhance colour, some add sheen or shine to the surface, others will wear off through foot traffic and may need re-application, and others again break down with UV light and will need to be re-applied. There is NO guarantee as to the effectiveness of the sealing agents used. We suggest sealing specialists are contacted for advice before just applying on of 50+ sealants available on the market.
Today ceramic tile manufacturers copy the look of Terra Cotta tiles in glazed form, which do not require the regular maintenance of unglazed clay tiles or sealant application and thus are easier to clean and maintain.

Porcelain tiles, due to their density and low water absorption properties are suitable for areas in sub-zero temperatures. Normal ceramics will absorb water, which when freezing expands, resulting in tiles breaking up. Since porcelains absorb very little moisture, they are frost proof or at least frost resistant.

Monocuttura Ceramic Tiles
This is the most popular/widely used type of tile for most floor and wall applications depending on the mix and type of clays used, their density or degree of hardness, influenced by the temperatures these are fired at. (Monocuttura as a literal translation means a single firing).
Various mixes of clays can be used to achieve lesser or greater density of body/bisque, onto which glaze is applied. Many finishes (Matt vs. Gloss vs. Satin/Sheen, patterns and/or slip-resistant surfaces,etc.) can be achieved during the glazing process by adding specific ingredients either onto or into the glaze. Patterns/motifs are mostly screen-printed onto the bisque/body in glaze form, which is then fired into the surface. The more sophisticated the screening machinery the wider the options exist with regard to texture, design or surface finishes. Glazes / glass make the surface waterproof or impervious to stains and thus are more easily cleaned and maintained. Generally detergent soap and water is sufficient. Glaze hardness and firing temp will determine the application of the product - whether it is suitable for outdoor use, commercial or industrial applications such as shopping centers, or high traffic areas.
 Porcelain Tiles
Currently only imported products are available on the local market. These tiles are extremely dense with a low degree of water absorption and hard wearing, and thus more expensive than Monocuttura Ceramic Tiles.
They are divided into 3 categories:
Full body unglazed - where the colours are obtained by dispersing mineral oxides throughout the bisque. This will result in the colour being consistent throughout the body. Water absorption is generally less than 0.5%, but need only be less than 3% to be considered non-porous or fully vitrified. Suitable for heavy traffic areas and industrial applications.
Polished porcelain - as above, but the surface is polished with a pumice stone type material creating a gloss appearance. The Matt or unpolished tiles can be used in conjunction with the same tile in gloss/polished form to create more interesting effects. Polishing the porcelain is an expensive process, which always results in polished material being more expensive than unpolished.
Glazed porcelain - where the tile is glazed to obtain specific finishes/effects.
Note: When purchasing porcelain tiles, due to the density of bisque a better quality (higher bond strength) of adhesive is required for laying of tiles.