By: Todd Wheatley
(c) IQ-2k   04-30-14

This is a companion article to my YouTube video of the same name. It is important to note that SANDSTONE is the type of rock used in the video and must be selected with some care. Most sandstone like slate or mica has many fine layers offering instability for easy breakage. These layers only run in one direction so easy breakage one way does not mean easy breakage in the other. Some sandstone may be exceptionally hard and not offer breakage in any direction.

Layers are the key to selecting the right sandstone. If the layers are too pronounced the rock will break too easy and will not hold up over time. If no pronounced layers are visible the rock will be too hard to break by conventional means. With the proper care sand- stone will break cleanly "with the grain" and "across the grain" as well. The porous nature of the rock can be used to cut "across the grain" provided a deep enough groove can be cut to control the grain instability.

The disadvantage of porous material comes with aging. Sandstone will slowly turn green after a decade or two of exposure. Algae and mold grow in the pores given the proper mix of moisture and sun shade. You may be able to see this discoloration in the rocks broken in my video. While I split the rock to gain greater coverage a discolored rock can be "shaved" to restore its former luster.

It is best to use a rock chisel, however any improvised tool can be used. As you can see in my video I am using a small hand ax and rock chisel to break the sandstone ... first I mark a straight line, then I move the chisel up and down the line till the rock breaks. Hopefully you will note that I do not deliver a hard blow to the chisel, but instead make firm contact. I do not want to cleave the rock. I want a continuous crack to develop until the rock breaks.

Cleaving the rock may cause a non-uniform face and most likely damage the rock. A nice flat rock has a more aesthetic appeal and can be used for making etched rock which will be shown in a later video. I will also show this technique can be applied to larger rocks as well.


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