Soaking

The flakability of some stones can be enhanced by protracted soaking in water. This was recognized by gunflint manufacturers who preferred to work stone immediately after it was extracted from the ground. Just excavated stone is referred to as "fresh" stone, while pieces left on the surface for long periods are called "dessicated". Soaking does not have as a dramatic an effect as heat-treating, but it will improve your capacity to thin and shape the piece using either soft-hammer percussion or pressure. Flakes will penetrate further and can be detached at more acute angles.

Types of Stone

The type of stones which can be improved by soaking include most of the cryptocrystalline sedimentary silicates: flints, cherts jaspers, opal, agates and chalcedonies. Igneous rocks like obsidian and basalt will normally not be improved by soaking. Some metamorphic forms may be improved by soaking, but the vast majority will not benefit.

How to tell if a stone will be improved by soaking

Dip your unknown flake and an obsidian flake in some water and then remove them both at the same time. Watch the surface of both flakes while the water evaporates. If the unknown seems to become dry significantly faster than the obsidian, the stone is likely absorbing some of the water. This means it is a good candidate for soaking.

How to do it (Modern Technique)

Reduce your rock to flake blanks. Get a small watertight container, preferably one with a tight fitting lid (Tupperware seems to work fine). Fill with water. Drop in flakes or blanks, make sure all pieces are completely covered. Seal lid tightly. Wipe up mess. Label the container with the date started. Put someplace out of the way. Check water level every couple of days. Wait at least one week and preferably longer before attempting to work the soaked pieces. WARNING: Thick pieces will take a very long time to become fully saturated.

How to do it (Ancient Technique)

Reduce your rock to flake blanks. Find an area of boggy ground. Dig a small hole. If water pools at the bottom of the hole, you are deep enough. Throw in your stone. Fill in hole. Mark hole with a marker or flagging. Go away. Come back in a month. Search for hole. Dig up your rock.

Knappers Anonymous was prepared by Tim Rast and is being updated by Mike Melbourne