Categorized | Using Nature

Cyanide from Fruit Pits

A guy I know, Buck, is collecting fruit pits from peaches, nectarines, plums, etc. I didn’t imagine him to be the craft-making type, so my curiosity pried him for more information. The deeper I dug the more fascinated I was.


To make a colored case hardening.

What is that?


Fruit pit

This is and old-style predecessor of all metal coloring typically employed in the gun industry. They didn’t do heat treating long ago. Soft, low-carbon steel was used, but strong materials were needed for guns. At first case hardening was used but didn’t offer any aesthetics.

How is it done?

Color case hardening occurs when soft steels were packed in a reasonably airtight container in a mixture of charred leather, bone charcoal and wood charcoal (which result in carbon being formed*). The contents were then heated. The longer the heat was applied the thicker the case hardened. At the end of this heating process the container is removed from the oven and cooled in water. The cooling causes patterns of colors to appear as well as hardening the part. It’s also called blueing and only works on steel turning it a rich, iridescent, peacock blue!

So why do you need peach pits?


It’s surpising what’s in a peach pit.

The coloring is affected by what is used to make the carbon base*. To make the pits into a carbon it has to be heated to the point of burning in an airtight container. There is a small hole in the top for only the gases to escape. These gases can be lit with a match to act as a pilot light or indicator. When the ‘pilot’ goes out then it’s finished burning and has become carbon.

What do people use if they don’t have fruit pits?

They use cyanide and arsenic, both toxic chemicals to make the equation.

So Buck wants all the pits he can muster to experiment with. I wish I’d known about a month ago when I canned mine! I could have given him a few cups worth.

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One Response to “Cyanide from Fruit Pits”

  1. Sherry if you post this to your FB, maybe someone will have a bag of pits to share with your friend Buck.
    I love the bluing by the way it’s really gorgeous on small handguns. Who knew. The things you can learn from talking to someone for 5 minutes. I try to do that once a day if I can. I learn a LOT. Thanks for sharing.


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