When natural stone paving slabs are quarried around the world, the material is extracted from the rock face and cut to size using large industrial saws and then, often finished by hand. The quarries are dusty, dry environments and the paving is usually not washed prior to shipping therefore it's more than likely the paving will have a certain amount of quarry dust on the surface of the stone.

Whilst in transit, the paving will gently move with vehicle vibration and this causes the dust to rub onto the adjacent paving and create scuff marks. These are superficial markings that will weather off once the stone is laid and used for normal foot traffic.

Similarly, when the dust is coupled with humidity inside the plastic wrap during shipping may cause the dust to stick to the paving creating a white film on the surface of the stone. Again, this will weather off after a short period of time.

It is also worth noting that upon arrival in the UK, the goods are often covered in fumigation power to eradicate any unwelcome insects to our shores. This too can appear as a white powder or film on the surface of the paving.

None of these effects are permanent and will either weather away naturally or may be cleaned once the paving has been installed.

Sometimes, especially on laid paving or with concrete paving slabs and blocks, the white marks can be caused by efflorescence. These are formed as a result of a chemical reaction between cement and water which migrates to the surface of the stone and then reacts with carbon dioxide in the atmosphere to create calcium carbonate deposits on the surface of the paving.

Efflorescence is unpredictable but often occurs when the paving has become wet and then dries slowly. It is not a fault within the product and in fact, when seen in concrete paving, shows that the paving is of good quality with a high cement content. Efflorescence appears with both concrete and natural stone materials and in the latter is caused when the mortar on which the paving is laid, migrates through to the surface of the stone. It will gradually disappear over a period of time.