HOW I Do It--The Artist's Instructions for Knapping Points

摘要

I have selected a Brazilian Piranha (also spelled Pirana) agate nodule for this point. The name derives from its dig site in Brazil. It's quite translucent, with swirling bands of several colors. I slabbed it on a 24-inch saw. It's always a judgment call on how to orient rocks in a saw so that the cut slab will display the maximum amount of color and banding patterns. This one has turned out to be outstanding. Before trimming any cut slab, 1 inspect it closely, using a backlight to detect undesirable cracks, crystals or voids. If one or more of these are present in a trimmed slab, it will be impossible to knap it properly. They are also likely to cause a cut slab to crack or break during the heat-treating process.