Question

Expectations of natural stone paving

Natural stone cannot be beaten with its beautiful colours and characteristics that only nature can create. The finished effect of the completed project is stunning, however if you examine each piece of stone at close range, you will see what may be perceived as imperfections, however these are actually part of the character of the stone, the manufacturing process or the journey the stone has taken to get to you and it's important to embrace these as part of the beauty of a natural product. Allowances should be made in the quantity purchased if personal choice means that natural characteristics are considerere undesirable.

Typical characteristics are as follows:

Colour Variation

There is a good chance of colour variation between slabs with natural stone, especially with sandstone paving, although some ranges such as grey sandstone are less prone to colour variation than some of the other shades. It's possible that one pack of stone will have a mix of colour tones whereas another pack may be plain coloured between the slabs and this is why it is always recommended that all packs are mixed when laying to ensure an even and varied selection of tones across the entire area. The variety of colours seen or not seen as the case may be, is purely down to the natural features of the stone and cannot be guaranteed either way. Colour variation tends to be more significant when the stone is wet whereas the stone will be more pastel toned when dry.

With most natural stone and especially sandstone and limestone, the colour of each range is determined by the quarry from where the stone originates. Depending upon the area in the quarry from which the stone is taken will determine the predominant colour tones at that particular moment in time. It is quite typical in sandstone to see pink, lilac, buff and grey tones appear sporadically even though the predominant shades may be different. In limestone, it's possible to see copper tones and occasional white veins amongst other shades.

It is quite usual to see a mix of shades in all types of natural stone and we describe the predominant shades that would usually be typical with each range of stone, however it is always possible that other colours may be seen.

Mineral Content

Natural minerals can appear as various markings within the stone including veins, crystallisation, fossil imprints and random patches. Examples of these include:

Fossil Imprints

These appear as black or coloured markings of blotches within the stone and are more frequently seen in stone such as fossil sandstone. They are natural markings and can sometimes resemble fern or other leaf prints and other times may just be darker colourings within the stone. Fossil imprints are highly desireable natural markings.

Veins

Veins are seen in various types of stone, but especially limestone, slate and granite. These usually appear as either white lines or what look to be very fine hairline cracks. The white lines are actually quartzite veins running through the stone and the fine cracks are simply markings on the surface which will cause no problems with the paving itself.

Iron Deposits

Iron is present in many paving materials and this can appear as brown or orange colouring within the stone. Sometimes as the stone weathers, the markings may become more prevalent and in other cases it may not be noticeable at all. The use of brick acid and many general patio cleaners contain hydrochloric acid which will cause the iron within the stone to oxidise (rust) and should never be used. Similarly, many weed and moss killers or lawn feeds can have the same effect, especially if they contain ferrous sulphate. Pavetuf Rust Remover will help to lessen the natural colouration of iron within the stone.

Surface & Edge

The surface and edge finishes of natural stone will sometimes contain small chips, dips and raised areas, blemishes and minor imperfections on the surface or edges which can either occur during the manufacturing process or will form part of the natural features of the stone. Sawn edge paving slabs may contain irregularities which are often caused by the cutting blade hitting a larger mineral within the stone. This is not a fault with the product and once laid will have minimal impact.

Dust, Scuffing & Tool Marks
Dust Some pieces of stone within a crate may be affected by a dusty sediment, scuffs or tool marks. These are more prominent when unpacking stone that is dry and dusty within the crate. The dust will come from the cutting and sawing process undertaken when the stone is cut into the shape and size required. It can often come from the calibration process where the stone is cut to a regulated thickness. Calibrated stone will have corrugated or partly corrugated underside. The paving is usually lightly washed as part of the processing, however this can sometimes leave a dusty residue on the surface which will usually wash off.
Scuffs Sometimes, the stone may have rubbed together in the crate during the shipping to the UK and this can leave light scuff marks on the surface. These will usually wash away or rub off with light weathering.
Tool Marks Other paving may have light tool marks on the surface where the stone has been handsplit along the natural bedding lines within the rock. These tool marks are part of the rustic charm of stone cut by hand and will gradually weather off over time. Alternatively, adequate provision should be made to order additional material to avoid using stones with characteristics such as these.

Dimensions

Natural stone will always have a variation on dimensions and thickesses in accordance with British Standard BSEN1341:2012 and as a result of manufacturing tolerances. For this reason, it is necessary to build margin into joints between paving slabs, and make up thickness variations within the bedding mortar.

Once laid, any individual markings or natural characteristics of stone are barely noticeable as the overall effect of having a natural stone patio with its beautiful array of colours, some subtle, some vibrant and the gentle blend of textures that merge seamlessly with the nature in your garden are what makes the biggest impact.

Expectations of natural stone paving

Colour Variation

Mineral Content

Surface & Edge

Dust, Scuffing & Tool Marks

Dimensions