Slate is an aesthetically beautiful stone that has been used in construction for centuries. They make fantastic roof tiles, able to provide excellent insulation for a home and withstand harsh weather conditions, but they can also be used inside the house as floor and wall tiles. Slate comes in a variety of naturally occurring colours and styles, making it an incredibly versatile material.
But where do these slate tiles come from? How do they go from being mined out of the ground to the tiles on our roofs, wall and floors? Well, here’s what you need to know about the step-by-step process or mining this natural, raw material and turning it into the tiles we know and love.
Before the process can begin, quarry sites need to be surveyed and tested to ensure they are appropriate areas to extract the material from. The quarry rocks need to be tested to ensure they are strong enough and suitable for their end-use. The tests are done to discover if there are any weak rock layers that will be detrimental to the stone’s end quality.
The stone will only be extracted from the quarry for use when the tests have verified the quality and purity of the slate.
The raw slate is then sawn from the quarry in large flat slabs using a diamond beaded steel cable – or sometimes detonation is used, but this is done at a minimum to keep slabs large and prevent material loss. The extraction must be done carefully and with precision, as the process can affect the material’s integrity.
Once the slabs are free, they are transported to factories to transform them into tiles.
Using diamond-tipped blades, the slabs of slate are then cut into more manageable pieces. During this process, impurities are also removed from the raw material without the use of harsh chemicals. The cuts are then inspected for their end-use. Most slate will be used for roofing, while a portion will be allocated for architectural use. Slate destined for architectural use will need to be of the finest quality and have large dimensions.
The slate cuts are then sent for splitting, where they will be split down to a specific thickness, a process which is done by hand. This technical step of the slate processing process has been done for many centuries.
Splitting is a specialist process that splits the slabs into the correct thickness while maintaining the material’s integrity. The slabs are split where a natural break occurs in the slab to give it a clean, straight split.
Split slates are then ready to be trimmed to a specific length for its chosen purpose. Traditionally trimming was done by hand, but nowadays machines are used to trim the slate to perfect measurements for installation.
After the process is finished, the slate will go for a final inspection where the slabs will be sorted and classified for use. Slate for roofing will be stacked onto pallets for storage. Architectural slate for panelling, tiles, counter-tops and chalkboards etc., will go through various processes before it is completed. The slate will be gauged and then honed to various finishes and may even be flamed to give it an even textured finish that removes traces of the saw blade and any irregularities.
Once the slate has been completed and stored away, it can be delivered across the country and the world for its intended purposes. Here in the UK, we have a variety of slate quarries across the country, including in Wales and the Lake District.
Different parts of the globe provide different slate varieties, as the colour is determined naturally by the geological conditions at its formation, which varies from place to place. Wales is known for its stunningly beautiful variety of blue slates.