Any water feature can sit
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Geologists will tell you that slate is a metamorphic rock composed of layers of clay or volcanic ash. Most people are more familiar with it as a roofing material, or something to write on, on the line between papyrus and vellum, and paper and IPads.
Slate is easily recognisable, a dark grey, smooth stone, found in Cornwall, Wales, the Lake District and Scotland, as well as other parts of the world. In some places there are open quarries, such as at Delabole in North Cornwall. Welsh slate is often mined hundreds of metres underground, the deeper you get the older the slate.
Slate was formed millions of years ago from shale or volcanic ash, fused together under pressure. It formed into very fine layers, which are individual to every slate, much like the grain of wood. Slate is carefully split along this grain to leave the flat surfaces which are so recognisable. A good piece of slate with no defects will ring when tapped. Some slate has tiny flecks of iron pyrites in it (fool’s gold) or other minerals, which gives individual pieces a sparkly, coloured or rusty appearance, adding to the unique character.
Over the centuries, slate has been used for many things, and worked its way into the English language. From at least Medieval times, slate has been used for roofing, and cladding buildings. Being smooth and lightweight, slate was also used as a writing material. Marks can be made and erased, and many children over the years learned to write on slates. And in bars, a slate was used to note bar charges, and tabs. Hence the phrase ‘a clean slate’ or ‘blank slate’, when you’d paid your dues.
Much of the new slate I use at HMIC is Cornish – often from Delabole, but also from Trevillet Quarry, near Tintagel. Slate from different areas has slightly different characteristics, and I sometimes use Spanish slate, which is finer, making it easier to punch holes in.
I also use reclaimed slate, which has been taken from roofs across Cornwall. It’s not possible to say which exact quarry they came from, as most farms used to have a quarry within a few miles. As time has gone by smaller quarries have closed and its now mainly Delabole Quarry that supplies Cornish slate in large quantities.
Reclaimed slate often has holes in it, or marks from the original use. This makes each piece a unique, and therefore all the items I make from reclaimed slate will be slightly different from one another. I’ll have to allow for chipped edges, or broken corners. Sometimes I can use the original fixing holes, but this doesn’t always work out.
If you are using something made of slate with food, eg a lazy susan or serving plate, then it will be covered in a special coating. This will protect the food from anything in the slate, but it won’t entirely protect the slate from any grease in the food. I would recommend lightly coating your slate with cooking oil, roughly once a year, to prevent it from absorbing grease, which would stain it.
If you have purchased a garden ornament or water feature, you can be sure that it is frost-proof. Slate absorbs very little water, which is why it has been used for roofing for so many years. However, if you have a water-feature, I would recommend emptying it if the temperature is likely to drop below freezing, so that the seams aren’t popped as the water in the reservoir solidifies.