Why Terra Sigillata?

Perhaps the first question I get when telling folks about the blog is:

What’s Terra Sigillata and why did I choose this as the blog name?

What follows is a periodically-updated post that ran originally on 20 December 2005 at the blog’s first home at Blogger.

If you Google, “Terra Sigillata,” you’ll get a number of hits for various clay pottery recipes. It’s made by a differential sedimentation process of clay – very complicated stuff – requiring the use of a deflocculant to separate out large clay particles from the small ones. Terra sig, as it is known among pottery hipsters, is then used to coat finished pieces to produce a very smooth, high luster and waterproof finish.

Since originally writing this explanation nearly five years ago, clayworkers and other artists who’ve stumbled on the post have directed me to some of the many variations on terra sigillata. The best so far has been this copyrighted recipe and description by Vince Pitelka at the Appalachian Center for Craft at Tennessee Tech from research he had done since teaching ancient clay arts classes at the UMass-Amherst. Take a read later on because the process is really an ancient chemical method and is quite fascinating.

What does this have to do with pharmacology and natural products?

Terra Sigillata is a Latin term that literally means “sealed earth.” In the common potter’s vernacular, the term is used to describe its use as a high-lustre seal on clayworks due to the uniform orientation of kaolinite crystals. But, in ancient pharmacy history, Terra Sigillata refers to the first trademarked drug product, a small clay tablet or planchet bearing an official mark of authenticity. In this case, the “seal” was a mark for trade and marketing purposes.

Those of you with pharmacy backgrounds may also know that the notation for dose, duration, and route of administration on a prescription is abbreviated, “Sig.,” short for Signatura, meaning to sign, seal, or mark.

Dirt as medicine

Yes, pre-Christian cultures ingested dirt (but only special dirt) as medicine. (Admonishment from my soil scientist colleagues: I meant to say, “soil” – sorry.). The medicine known as Terra Sigillata began as a unique clay first harvested around 500 B.C. from a particular hill on the Mediterranean island of Lemnos, now part of Greece. Dug on a special day annually in the presence of governmental and religious dignitaries, the clay was rolled to a defined thickness and pressed with an official seal by priestesses and dried in the sun. Kind of reminds me of my favorite beer, Samichlaus, brewed once a year on 6 Dec.

Known as geophagy today, the practice is not as odd as it sounds and is common to primates. Today, we now know that clays contain kaolin (an active antidiarrheal component formerly in Kaopectate), minerals like iron oxides and others like calcium carbonate and magnesium hydroxide that may have served as nutrients or antiacids. Moreover, various ethnomedical cultures have encouraged clay consumption by pregnant women, both to ease nausea and to adsorb dietary alkaloids and steroids present in the plant diet from harming the developing fetus.

Having lived in the southern US for a third of my life, I’m also aware the red clay of the southeastern region is highly regarded for settling the stomach. According to John and Dale Reed in “1001 Things Everyone Should Know About the South,” the practice of geophagy seems to have originated in Africa and was widespread in the 19th century South among the poor of both races. The Reeds claim that the taking of the clay is the source of “sandlappers,” a nickname for South Carolinians. Heck, I’ve even heard Michael Stipe of R.E.M. (and Athens, GA) remark that red clay is in his blood, although I suspect his claim may be more figurative.

The inspiration

I learned of all this great history when I began leafing through a classic 1965 pharmacy history book, “Great Moments in Pharmacy History.” (Washington State University’s College of Pharmacy received permission to post the images online; here is the painting and brief description of Terra Sigillata.) The drug company then known as Parke, Davis & Company commissioned Robert A Thom, a Birmingham, Michigan artist, to prepare paintings of historical scenes to accompany historical text collected by Prof George A Bender from pharmacy sources worldwide.


It’s a great book that can be found through e-tailers focusing on out-of-print texts. If you went to pharmacy school anytime since the mid-1960s, you know what I’m talking about because Thom’s unmistakable portraits can be found in labs and offices in most US colleges of pharmacy.

This excerpt from Great Moments described the subsequent uses of Terra Sigillata that will be of interest to many, especially fans of Pulitzer prize-winning science writer, Deborah Blum, whose book, The Poisoner’s Handbook, has been one of my top reads of 2010.

In the early days, and even up to the early nineteenth century, Terra Sigillata was used as an antidote for poisons as well as in the treatment of dysenteries, int ernal ulcers, hemorrhages, gonorrhea, pestilential fevers, complaints of the kidneys, and eye infections. The most striking feature of this drug, however, was the way in which it was marketed, and the method of identifying it and warranting its origin from a definite source. The great demand for Terra Sigillata and the good business that the sale of these troches brought caused people in almost every country in Europe to look for similar earths. This trademarking to protect the rights of seller and buyer today has behind it the sanction and approval of some 2,500 years of man’s experience in world commerce.

As I wrote yesterday, I am a natural products pharmacologist possessed of great admiration for medicinal chemistry and pharmacognosy. But when thinking of a name for this blog, I didn’t want to restrict it to plants or fungi or soil microorganisms because creatures big and small, terrestrial and marine, have been used as sources for medicinal agents. I had certainly known that my predecessors had been culturing soil for novel medicinal-producing organisms since Selman Waksman first discovered streptomycin (although credit for this Nobel prize-winning discovery has increasingly been attributed to Waksman’s graduate student, Albert Schatz, who incidentally grew up across the street from the Passaic, NJ, hospital where I was born).

But I frankly hadn’t realized that the Earth itself had been used as a medicine.

Hence, Terra Sigillata is a metaphor for the fact that the Earth itself has provided medicines to various cultures for centuries.

The trademarking aspect of Terra Sigillata also holds significance for thinking about how important drug branding has become in our current culture, both for the buyer and the seller. Whether declared by a priestess, a charlatan, a shaman, a late-night infomercialist, or a pharmaceutical or biotechnology company, branding carries with it some implicit guarantee of quality or assurance of purity of authenticity.

But not always. That’s why we write Terra Sigillata.