Do you really know what granite is?

The use of granite for house signs and kitchen tops is becoming more popular, but do you really know what granite is? Granite is quite simply a type of very hard rock or stone, it is dug from the ground or blasted or cut from the side of mountains, this is called quarrying. The aim of the quarry is to produce large rectangular blocks, some of these blocks can be huge and weigh up to twenty tons! Try to imagine a block of stone 6 feet by 6 feet by 12 feet made of one of the hardest and most dense materials in nature.

Now lets be clear, this is the same stone or rock as is found in our rivers and on many of our beaches all around our coast, especially in Scotland, Cornwall and Devon. Those rocks have been broken and shaped by millions of years of glacial activity but many of them are granite just the same as our blocks.

The blocks are now sawn into sheets of a useful size, the saws are massive beam saws with rows of parallel diamond tipped blades that move backwards and forwards lubricated by water, the blades slice the granite block rather like a bread slicer cutting up a sliced loaf! sounds simple doesn’t it, but granite is incredibly hard, the saws are deafeningly noisy and the process for each block takes days.

Up to this stage the whole business is an act of faith, remember no-one has ever seen this piece of million year old granite, if the stone is seriously flawed or not an acceptable colour all of the work so far is wasted, this will be the first opportunity to see the colour and markings of the stone. The newly cut slabs are called scants, they have a rough and pitted face, covered in saw marks, it is difficult to even see the real colour, but by throwing water over the face, the colour and markings become visible and it is possible to see the potential of the scant.

The scants now go for polishing, they are laid flat on polishing machines which used to be called Jenny Linds, they are rotary polishers with large spinning heads that can be changed with different grades of diamond abrasives.

I’m not sure if the modern giant computer controlled versions have such a quaint name, but apart from the name the computers and the size, the principle is the same. Starting with a coarse grade to grind out the worst marks and grooves the polishing head moves backwards and forwards over the face of the granite in a controlled an even pattern for hour after hour, as each new grade is applied the colour and nature of the granite becomes more apparent, until with the final superfine grades the granite takes on its brilliant polish, the amazing patterns and colours are now seen in their full glory.

But just how hard is granite? Granites are almost impossible to scratch deeply with anything other than high grade steel, tungsten or diamond. Granites are extremely resistant to staining, one of the few things I have found will stain some granites is beetroot juice! Though it has to be left for some time to do any real harm. And lighter coloured granites may stain with rust from dripping guttering etc. Granites are extraordinarily resistant to the effects of rain and sun, and most corrosives found around the home have little effect.

I have been a Stone mason for forty years, but I never cease to wonder at this miracle of nature, I often wonder who was the first man to try to polish a piece of this super hard stone, whoever he was he was a genius!


About the Author:
Steve Walker has been a stone and marble mason for 40 years, working in almost every type of stone marble and granite. He is now the sole owner, craftsman and teaboy of StoneEngravings House signs