You don’t need to be an expert to guess the basics of how Indian sandstone and other sorts of natural paving slabs are made; they’re quarried, and then cut into paving slabs. And yes, those are indeed the basics, but the full process is a little more complex than that - there are quite a lot of steps involved in bringing you the quality Indian stone with the sorts of beautiful finishes you’ll see here at Bridge Street Stone.
So this week, we’re taking a quick look over the manufacturing process that goes into creating natural stone paving slabs like our Kota Black or Autumn Brown Indian stone, and explaining a little bit about what happens in each stage!
Here’s the process in brief:
- Quarries are carefully selected for the best quality stone
- The stone is excavated from each quarry, and sent to stone cutters
- Large blocks are hand-cut into paving slabs, then sent to be finished
- The paving slabs are finished and stacked, ready to be laid
So, let’s explore the process in a little more detail!
How Indian sandstone is sourced
Various companies source their sandstone products from all over the world, but here at Bridge Street Stone, we source all of our Indian sandstone from quarries in India. We have addressed where we get our Indian sandstone from before on the blog - don’t forget that that India is a truly massive country, with a very rich and diverse geology. Every year it exports massive amounts of sandstone, limestone, slate, granite and more.
This is part of the reason why ‘Indian stone’ is such a broad-ranging term, as different regions of India are home to different colours and varieties of sandstone and limestone. Kota Black, for example, comes from quarries in the Kota region of India, hence the name!
As you might expect, natural stone paving suppliers like ourselves are very careful in how we source our stone. First and foremost, we’re committed to providing our customers with high quality products - but also, there are ethical concerns. The unfortunate truth is that conditions for quarry workers can vary between different quarries in India, as labour is exceptionally cheap in some parts of the country. Therefore, British companies like ourselves use information from the British Geological Survey and Modern Slavery Slavery Act, as well as tools like the Ethical Risk Index, to choose suppliers who can guarantee that all-important mix of product quality and ethical working practices.
How Indian sandstone is extracted
There are a number of different methods typically used for extracting Indian sandstone from the ground. One of the most common is to make use of a hydraulic excavator with a breaker or a pecker, striking the stone at naturally-occurring faults and joins. Efficiency is a key concern at this stage, and quarry workers have to take care to minimise waste so that they can maximise usable material from the quarry. Upstands are added to the blocks after they’re extracted, which makes things easier and safer at the processing stage.
The sandstone cutting process
Once the sandstone has been extracted, the stone blocks (which can weigh as much as 10 tonnes) are sent to get cut into slabs. This is typically done with industrial-strength saws, which are edged with diamonds hard enough to cut stone. These are sometimes circular saws, but one of the most efficient (and widely preferred) methods is to use steel wire saws. As soon as the slabs are complete, they’re now ready for finishing.
The finishing stage
As soon as the sandstone has been cut into slabs, they’re ready for finishing. Natural paving stones have lots of different types of finishes for customers to choose from, including riven, calibrated, tumbled and sawn. The stones are generally finished from behind the safety of protective screens, which help employees avoid the risk of inhaling the silica dust that’s a byproduct of the process. (Silica dust can cause severe and long-term lung conditions.)
This is also where the stand edges from earlier come in useful too, as they prevent the stones from moving around during cutting. These blocks are incredibly heavy, so uncontrolled movement would be a potentially deadly safety hazard!
Here are some of the various finishes of natural paving stones:
Riven
Riven sandstones have a rough texture, having been been expertly hand chiselled to give them a grooved and naturally imperfect appearance. This gives them a raw and traditional sort of feel, making them a popular choice for outdoor environments and a particular favourite for rural properties.
Calibrated
The word ‘calibrated’, in terms of natural stone, generally refers to its thickness. Calibrated stone paving slabs are of a consistent thickness, usually between 22mm and 25mm. Most of ours are 18mm, 22mm or 25mm, depending on the type of stone - some are softer than others, hence the need for a thicker slab. Calibrated stone is created in a strip mill, using closely-spaced diamond-edged saw blades.
Tumbled
Tumbled natural paving slabs are known for having a softer, smoother and worn appearance. Any type of natural stone can be turned into a tumbled stone - this is usually achieved by putting them through a tumbling machine, which is essentially a large, slow cement mixer. The tiles are placed into a rubber drum, along with a mixture of rocks, sand and water. As the tiles are rotated within the machine, the other aggregate and liquid in there acts to gently wear down the edges, leaving a softer-looking natural stone which often has a slightly chalky appearance.
Sawn
Sawn stone is another type of natural stone that’s known for its smooth appearance, which is typically done using heavy-duty gang saws. Sawn stone can be produced to a wide range of textures - once it’s been sawn, it’s then coarsely polished. The end result is a stone with a semi-smooth appearance - a versatile choice that fits right at home in multiple environments.
And if you need any help narrowing down your decisions, our experts are always around to help here at Bridge Street Stone! We’ve got a great range of natural paving stones and Indian sandstone in a wide variety of colours and shades, from Kandla Grey to Golden Leaf, and our expertise with these products is second to none. All are sourced directly from India, and we’re able to offer free delivery to most areas. To make an order, feel free to give us a call today on 01282 860571