Here's another of my favorite "finds" from the pages of Craft Horizons. I found this little gem in the June, 1971 issue. Aside from the fact that the process sounds absurd, there was something about this "George Gladstone" that made me a little suspicious.

When I did a little bit of searching for "Horseclay" on the internet (Google initially asked me whether or not I meant "horseplay"...but I assured it that I did not), my suspicions were confirmed, and I learned that the author was none other than Clayton Bailey, ceramic prankster sans pareil.

Here are Bailey's instructions from his website:
This collection of test tiles demonstrates Clayton's discovery of Horseclay, and explains his Internal Combustion Ceramic process:
- Mix together 50% pulverized Quarter Horse Manure and 50% Clay.
- Add water, and use the clay immediately. Prolonged storage will cause sprouting of the seeds in the manure.
- Ignite the object with a flame when it is thoroughly dry. (Works best in an insulated kiln chamber.)
- The fired object is light and porous. The honeycomb structure of the fired clay makes Bare Hands Raku possible.
Ah.....bare hands raku. I suspect that the original letter was written in the early early part of April. Do all of my suspicions mean that you shouldn't rush out to the pasture and start experimenting with "self-combustible" ceramics? Don't let me stop you. I'll let you know if I unearth any responses from earnest Craft Horizons readers.