Monday, September 15, 2008

Testing Stones for Carving, Part 4

Today's test is specifically about softness of the stone.

This is important for the beginner especially. With limited tools and experience, you want to start with soft stones.

To test for softness, it is best if you have a point or chisel and possibly a rasp with you. Before you take any tools to the stone, be sure to ask. Most reputable dealers will say okay, but you haven't bought it yet and you will be scratching it up, so I ask.

Take your rasp or file and rub it across the stone. Does the stone yield easily? Either flaking or creating a powder? That indicates it is probably a soft and workable stone.

You can also take a chisel or point and hit a small corner of the stone. If the stone chips off easily it is soft.

On the other hand, a stone that appears soft, may be too soft--or have other issues.

White marbles that have been outdoors in the weather can become "sugary". I learned this the hard way. It is a distinctly different thing than being "soft." When the rasp runs across the stone if the powder is like powdered sugar...keep testing! Take your chisel to a bit of the stone. If the stone feels like it is disintegrating, pass on that stone. It will literally dissolve while you work!

If the stone is not a white marble and you think you like it, wet a small area and run your finger nail across it. If your fingernail can scratch it, it is an extremely soft stone--in the neighborhood of soap stone. These can be beautiful stones, but the scratch very easily and so it will be more difficult to have a finished piece without any unwanted scratches.

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