Ouch, ouch and ouch! Last week I had fingertips, this week I don’t.
I’ve been making another of my not-yet-famous marble clouds. The production process sounds simple: whack a few bits off a block of marble with a pointy chisel, shape up the resulting hills and hollows a bit with a flat chisel, smooth them roughly (or is that, ‘rough them smoothly’?) with a grindstone, then finish the surface with sandpaper – leaving enough time for an afternoon nap and a nice cup of tea.
The reality is slightly different. Marble’s an interesting material to work: it’s simultaneously hard and soft. When you’re chiseling the basic shape in, the stone feels crisp. You need to give it a good whack to make the chips fly, and the resulting chips are sharp – but they crush easily. And when you get to the sanding stage, it acts as if it’s soft. Ordinary sandpapers will wear it to smoothness quite well.
The challenge comes when you’re trying to shape an internal curve. It has to be as smooth and well-shaped as an external (convex) curve, or else (once it’s polished) any irregularity will be, literally, glaringly obvious – the light will shine back off it. When it’s a shape like my latest cloud, there are dozens of these internal curves, and the smaller their radius is, the harder they are to get into. In the end, it’s a job for a fingertip inside a piece of sandpaper.
Unfortunately, the back of sandpaper is smooth, so it slides against the fingertip, and you get nowhere. The solution is to fold over the sandpaper, so that there’s a rough, grippy surface against the finger – which disappears at roughly the same rate as the marble you’re smoothing. Voila – no fingertips, and nails worn down to the quick. But the result’s worth it…
Getting Accumulus I to this stage involved sanding with progressively finer grade papers – first, 40 grit, then 80, then 220, 400, 800 and finally 1200 grit. This leaves a polish on the marble, and improves the transmission of light through it, giving that beautiful quality of fleshiness that marble has. In this case, it’s a piece of white Statuario marble from Carrara in Italy – the best there is. Enjoy.