Word of the Day: Bloomery

A bloomery in Bloomery, West Virginia

A bloomery is the earliest form of furnace used to smelt iron from its ore.  The bloomery produces a spongy mass of mixed iron and slag called a “bloom,” which is then repeatedly reheated and hammered to get rid of the slag and produce forgeable “wrought iron.”

The use of the bloomery has commonly been found to coincide with early stages of Iron Age technology throughout Europe, Asia, and Africa.

The bloomery process involves creating a bed of red-hot charcoal in a specially-built furnace.  Iron ore mixed with charcoal in a controlled ratio is then added to the fire. The ore is chemically reduced in the fire, meaning that the iron oxide is the ore in converted to iron without having to melt the iron.  This is important because primitive furnaces could not reach the melting temperature of iron.  The product of the bloomery is a spongy mass of metal mixed with molten slag, known as a “bloom.” In this form, the iron was not forgeable.  Repeated reheating and hot hammering is required to get rid of most of the slag, creating wrought iron, a much more usable product.

Iron bloom, Abbaye de Fontenay
An iron bloom from a bloomery, shown in the forge of the Abbey of Fontenay, France. Photo courtesy of Wikimedia Commons

Over time, the bloomery was refined, and then ultimately replaced by the blast furnace, which could actually melt the iron and create a much more usable product more efficiently.  By the end of the 19th century, the bloomery was, for most practical purposes, no more.

However, it’s a worth taking a moment to pause and reflect (with awe) upon the painstaking effort and accumulated knowledge of generations that led to the invention of the relatively simple but beautiful and ingenious bloomery.


Word of the Day: Yingzao Fashi

Yingzao Fashi palace type building

Yingzao Fashi is the romanization of the Chinese term meaning roughly “State Building Standards.”  It is the title of a landmark work in the history of Chinese architecture, first  published in 1103 AD by Emperor Huizong of the Song Dynasty. It had been compiled in 1100 AD by the then-Superintendent of State Buildings, legendary architect Li Jie (1065-1110 AD).

The Yingzao Fashi was the end result of Li’s monumental effort to consolidate hundreds of years’ worth of knowledge of building techniques and standards into one uniform standard, and one instruction manual to be used throughout the Empire to construct official buildings.

In my opinion, there are two things (among the many, many things) that make the Yingzao Fashi particularly fascinating to me:

First, it utilizes an ingenious and completely modular and scalable building system, using a very strict and limited set of component parts — a system which produces stunningly beautiful and incredibly durable buildings.

Yingzao Fashi palace type building
Illustration of a palace-type building, from Li Jie’s Yingzao Fashi. Excerpted from Qingua Guo’s article (referenced below).

Second, the system is based on the centuries-old traditional building method found in China and Japan, that uses only interlocking joinery (think large and sophisticated Lincoln Logs) and no fasteners (nails, pegs, and so on).

Yingzao Fashi illustration
An illustration from Li Jie’s Yingzao Fashi showing the tenon and mortise system for tie beams and cross beams. Courtesy of Wikimedia Commons.

It’s not clear to me from the readings, the length of time that the Yingzao Fashi remained the standard, but I at least know there was a second edition published in 1145 AD, and that parts of it were found included in the court documents of the much-later Qing Dynasty (1644-1911 AD).  The work was rediscovered and reprinted in 1932, spurring a renewed interest in traditional Chinese architecture around the world.

As for the durability of the buildings, according to author Qinghua Guo, some are still standing, though certain affected by the centuries and by more modern renovation.

For further reading on the subject, I highly recommend the article written by Qinghua Guo for Architectural History, vol. 41 (1998), titled “Yingzao Fashi: Twelfth-Century Chinese Building Manual.”


Word of the Day: Yelm

Thatched roof cottage, Germany

“Yelming” is part of the thatcher’s trade: to yelm is to prepare the gathered straw, sorting it by size, laying it out flat, and in some techniques, dampening it with water.

According to James Arnold in his amazing book The Shell Book of Country Crafts (if you’ve read some of my other entries, you already know how much I love this book), the thatching trade is one of the few to remain virtually unchanged for the centuries, and into the modern age.  A thatched roof is more than a fashion statement, it is a highly practical means of roofing a house.  Furthermore, though the skills take time to master, the most effective tools for the job have never been more than the jack (a pronged fork for carrying bundles of material), the mallet, the leggat (a grooved board used to “coax home” the straw or reed), and the scythe–the last two being incorporated in the seal of Britain’s National Society of Master Thatchers:

Seal of the National Society of Master Thatchers

In 1968, when Arnold’s book was written, there were between 700-800 working professional thatchers in Britain.  This number was on the increase at the time, as there was a renewed interest in thatching, which had previously been in decline due to several factors. These included the booming slate roof industry and the advent of combine-harvesting of wheat (a process that destroys the wheatstraw previously used for roof thatching).  To replace the wheatstraw, common reed (which had always been one of the materials of choice) was increasingly being systematically cultivated  and harvested.

Today, that number remains roughly the same, with about 900 thatchers in Great Britain (and about 60,000 thatched roofs).  According to the International Thatching Society, there are about 300 thatchers in Japan (with 100,000 thatched roofs), 1000 thatchers in Holland, and 400 in Denmark.  Sweden, Germany, and South Africa also have a lively tradition of thatched roofing.  Sadly, in the United States, the thatched roof remains a novelty, with a select few craftsmen (mostly transplanted from Europe) here to practice the trade.

A thatcher at work on a new roof
A thatcher at work. Photo courtesy of Shutterstock

Personally I’m fascinated by this craft that found its perfection so long ago, and has retained it for centuries.  It’s beautiful in its simplicity and practicality, and I have nothing but respect for the hardworking and skilled tradesmen (and the homeowners who love their roofs) who keep it alive.

Featured photo: A traditional thatched roof (with solar panels), Altensien, Germany. Photo courtesy of Shutterstock.

Word of the Day: Bort

Diamond bort

“Bort” refers to shards of small, impure diamonds, or the small fragments removed from gem-quality diamonds during the cutting process.  It is also a term used to describe low-grade diamonds, not of gem quality.  Both categories of bort are utilized mainly in a variety of abrasives.  The origin of the word “bort” is not entirely known, but is speculated to have come from the Old French “bord” or “bort,” meaning “bastard.”

Carbonado or “black diamond” is a dark-colored, impure diamond with a slightly different and more rare structural form and chemical composition.  It is composed of crystalline diamond, graphite, and amorphous carbon; it is the hardest form of natural diamond.  Like bort, it is mainly used as an abrasive and for diamond set drills.

Carbonado from the Central African Republic
Carbonado, or “black diamond” from the Central African Republic. Photo courtesy of Wikimedia Commons.

Though bort and carbonado are certainly less glamorous than the gem-quality diamonds, they are by far the more abundant and useful.  About 80% of all diamonds mined (representing around 130,000,000 carats or 26,000 kg per year) are industrial-grade.  With the highest hardness, thermal conductivity and melting point of any mineral, these humble-looking diamonds possess the properties which rank them among the most useful industrial materials in the world.

Open pit diamond mine, Sakha Yakutia
An open pit diamond mine, Sakha Yakutia, north of Russia. Photo courtesy of Shutterstock.

Featured photo: Bort as a combination of shards and crystals.  Photo courtesy of Wikimedia Commons.

Word of the Day: Propolis

Propolis at the edge of a beehive

Propolis, also called bee glue, is an aromatic reddish substance collected by honeybees from tree buds and bark, consisting of a mixture of tree resins, balsams, and waxes which are altered by the bees’ own secretions, esp. saliva and beeswax, and used by them to seal cracks in the hive and varnish the cells of the comb. (Thank you to the Oxford English Dictionary for this definition).

For centuries, healing properties have been attributed to propolis, and it is often touted as an herbal remedy or supplement.  However, even a quick scan of the literature (such as the articles found on sciencedirect.com) strongly suggests that most of the evidence for its effectiveness is anecdotal.  On a hopeful note, in vitro studies have supported claims for the anti-microbial effects of propolis, although actual clinical studies are nearly nonexistent (1).  Part of the issue is that the chemical composition of propolis is very complex and can vary widely and depends largely on the local ecology, especially the plants from which the bees are collecting the resins (2).

In Petra Ahnert’s wonderful book Beehive Alchemy, of the fifty or so recipes involving bee products, only three include propolis (salve, toothpaste and throat lozenges).  So it appears (for now, at least) that propolis is far more useful to the bees that it is to us.

And in my opinion, that’s really okay.

Featured image: Propolis found at the edge of a beehive.  Photo courtesy of beeinformed.org.


(1) Red Propolis: Phenolics, Polyphenolics, and Applications to Microbiological Health and Disease, (Irlan A. Freires, … Bruno Bueno-Silva, in Polyphenols: Prevention and Treatment of Human Disease (Second Edition), 2018)

(2) A worldwide yearly survey of new data in adverse drug reactions and interactions N.H. Choulis, in Side Effects of Drugs Annual, 2012 (entry on Propolis)

Word of the Day: Ashlar

Ashlar stonework Palazzo Rucellai Florence Italy

An ashlar is a large stone hewn to square sides, for use in building or laying pavement. It also refers to the particular method of stone masonry called ashlar or ashlar-work, which makes use of hewn stones, often made to a specific proportion, as opposed to rubble-work, which makes use of unhewn stone.

According to The Stonemason and the Bricklayer, a manual from 1891, by the self-described (but unnamed) editor of the “Industrial Self-Instructor”:

“The stones for the best class of [ashlar] work should be carefully proportioned, the length, depth and breadth having what is called a harmonious relation to each other [a proportion further described in the book].”

Anything less than this constitutes “sham” or “false” ashlar, which can only result in inferior and unstable stonework.

Example of the “broken ashlar” style of wall. Illustration courtesy of chestofbooks.com

In literature from the Middle Ages, there are references to “ashlars” used as weapons, being hurled from fortress walls at attackers below.  Whether they were made for this purpose, or the defenders were simply desperate enough to use the stones of their own buildings, I don’t know — either way, it would be a pretty effective missile.

The usefulness of ashlar-type stonework has certainly been recognized throughout many eras, and many parts of the world.

Ashlar wall at Machu Picchu
An ashlar-style wall dating to the 16th century, at Machu Picchu, Peru.

<a href="http://Rubyk / CC BY-SA“>Photo Courtesy Wikimedia Commons

Today, ashlar work is still very much alive and well, though its definition (at least, according to the author quoted above) has been expanded to include a number of styles that include a variety of types of dressed stone.

Still, harmony, stability, and fine craftsmanship lie at the heart of ashlar stonework, with the aim of creating a structure that will stand for centuries and beyond.

Unless, of course, one is aiming simply to throw it at an enemy’s head.

Featured photo: ashlar wall of Palazzo Rucellai in Florence, Italy. Photo courtesy of Shutterstock.


Word of the Day: Caoutchouc

Caoutchouc (also called “India rubber,” regardless of its source) is a natural rubber that is the first-processed form of the latex of certain trees and plants, particularly the rubber tree (Hevea brasiliensis), the white rubber vine (Landolphia spp.), and the Ceara rubber tree (Manihot carthagenesis).  It is the precursor to fully-processed rubber. It is distinguished from other varieties of natural rubber by the proteins it contains, which can cause allergic reactions in some people. Caoutchouc is used extensively in many applications, and is valued for its large stretch ratio, high resilience, and for being extremely waterproof.

The best-known source of natural rubber is the rubber tree (Hevea brasiliensis).  Native to Central and South America, archaeological records indicate that the latex of the rubber tree was first used by the Olmec civilization to make rubber balls used for the Mesoamerican ball game.  Rubber latex was introduced to Europe in the 18th century.  It’s usefulness was quickly recognized and exploited, with plantations appearing in several tropical colonial holdings in Indonesia, India, and the Congo.

In the Congo, the Belgian colonial rubber industry was based on harvesting the latex of the white rubber vine (Landolphia owariensis). By the turn of the 20th century, the rubber trade in the Congo had become notorious for its brutal treatment of the local people, who were often conscripted against their will and subjected to harsh penalties (including death) for not meeting production quotas.  Joseph Conrad’s masterpiece of literature Heart of Darkness was based heavily on Conrad’s experiences in the Belgian Congo.

Today, synthetic rubber is a widely-used alternative to natural rubber that avoids the allergenic nature of caoutchouc.  However, natural rubber is still a valuable industry, with most of the rubber today produced by plantations in Southeast Asia, Central and West Africa, and South America.

Modern rubber plantation, Malaysia
A modern rubber plantation in Malaysia. Photo courtesy of junglerubber.com.au.

The history of natural rubber has many fascinating chapters, form the Mesoamerican ballgame to the saga of Congo rubber, to the invention of vulcanized rubber tires and Henry Ford’s dream of a Brazilian rubber plantation utopia, and beyond.  The usefulness of caoutchouc lives on in thousands of everyday products in home and industry around the world.

Featured photo credit: Harvesting the white rubber vine (Landolphia owariensis), circa 1906.  Courtesy Wikimedia Commons.

Word of the Day: Fuller

Fulling Mill, by Georg Andreas Bockler

A fuller’s job is to “full” raw wool; that is, to remove the lanolin and other greasy impurities from the fibers to whiten it and prepare it for spinning and weaving.  In the European tradition, this usually done through the use of fuller’s earth (a naturally-occurring clay), and fuller’s herb (also called soapwort, Saponaria officinalis).  Depending on the end use of the wool, the fuller would also thicken the wool by felting it, or causing the fibers to mat together through pounding or mechanical agitation.

In Europe, the fuller was for centuries an important link in the chain of the all-important wool industry, from Medieval times to the late nineteenth century and the advent of the industrial revolution.

In modern times, the processing of wool is done by chemicals and machinery, and the fuller is no longer in the picture.  However, the legacy of the importance of this cottage industry (which, in Britain, was also called “tucking” or “walking”) lives on today in the common surnames of Fuller, Tucker, and Walker.


Word of the Day: Osier

The Welsh Cyntell, basket by Ruth Pybus

The name “osier” refers to a number of species of willow tree that produce long, narrow, flexible branches that are especially valued in basket-making.  It can also refer to the branch itself (also called a “withy”).

The best-known of the species is the common osier or basket willow (Salix viminalis).

Common osier (Salix viminalis)
The common osier (Salix viminalis). Photo courtesy of Van den Berk Nurseries.

The art and craft of willow basket-making is ancient and widespread, with long traditions in Europe, East Asia, and the Americas.  Willow-work is not limited to baskets, however.  According to James Arnold’s book The Shell Book of Country Crafts (1968), osiers (or withies) play a role in many essential crafts including: thatching, basketry, hurdle-making (livestock enclosures), and making coracles (a type of small lightweight boat) — among numerous others.

Willow basket, 1919
Willow basketry in the early 20th century United States. Photo courtesy of historichomeshowardcounty.blogspot.com.

The practice is alive and well today, though the economic and practical importance of willow-work of all types is far less than it was in previous times.  Still, there is a great deal of interest in the craft, and many opportunities, especially in the United States and Britain, to learn it from experienced crafters.

Willow baskets by Jane Wilkinson
Modern willow baskets by Jane Wilkinson. Photo courtesy of craftcourses.com
Modern willow baskets by Oxfordshire Basketmakers
Modern willow baskets from a crafters’ workshop. Photo courtesy Oxfordshire Basketmakers.

Featured photo credit: The Welsh Cyntell, basket by Ruth Pybus.  Photo courtesy of Potter Wright & Webb.

Word of the Day: Verdigris

The Magdalen Reading, by Rogier van der Weyden (1438)

Verdigris is the greenish-bluish film that is created on the surface of copper by the application of a dilute acetic acid. It has a long history of use as a pigment, in dyeing, in the arts, and in medicine.

The term can also refer to the greenish film that forms on the surface of brass, bronze, and copper as a natural result of weathering by exposure to air or sea salt.  However, the chemical compositions of the natural verdigris (copper carbonate or copper chloride) and artificial are different, and only artificial verdigris (copper acetate) has the uses listed above.

Statue of David Hume, Edinburgh, Scotland
Verdigris on the statue of David Hume in Edinburgh, Scotland (note the polished metal on the big toe, where the patina has been worn away by repeated touching – for good luck – by human hands)

The use of verdigris as a pigment and medicine dates back at least to its mention by Pliny the Elder (AD 23/24 -79) in his encyclopedic Naturalis Historia, but in all likelihood goes back further than that.  In the 15th through 17th centuries, verdigris in oil paint was a popular lightfast and intense green used by many well-known artists, including the Early Netherlandish master Jan van Eyck.  In the city of Montpellier in France, the manufacture of verdigris was a common household industry.  Montpellier verdigris, renowned for its quality as a pigment, was made by exposing copper strips to the vapors arising from distilled wine.

Jan van Eyck's Arnolfini Portrait
Jan Van Eyck’s Arnolfini Portrait (1434). Note the rich green (probably painted with verdigris) of the woman’s dress, a color that at the time was reserved for those involved in banking, thus denoting her upper class status.

Through its history, verdigris has also been touted as a treatment for a wide variety of illnesses, from leprosy to infections of the skin.

In modern times, however, verdigris — mostly due to its toxicity and relative instability as a pigment — has largely fallen out of use.  But not entirely: today it is found in industrial fungicides, as a dye, and architecturally as a patina for copper and bronze.

Featured photo credit: The Magdalen Reading, by Rogier van der Weyden (after 1483). Courtesy of Wikimedia Commons.