This satisfyingly chunky piece of glazed earthenware, featuring a roughly beaded rim, was once a fairly large, open vessel, probably a pot or a tall-sided bowl. Mocha ware, produced between the mid 1700s and the early 1900s, was relatively cheap and cheerful, pottery for using rather than admiring. Its defining features include its colouring, the linear decoration (usually combined with panels of colour or white background) and the “dendritic” design. “Dendritric” means “branching,” and in mochaware refers to a pattern consisting of a feathery fern-like tendrils, usually emanating from a main stem, typically coloured either black or blue. Vessels without the dendritic design are usually referred to simply as banded creamware or annular (ring-like) ware, in both cases due to the encircling bands of colour. It is only those vessels with the dendritic design that are supposed to be referred to as mochaware. We have found both in the garden, but the piece of mochaware is the most impressive, both in terms of solidity and distinctiveness.
The name mocha derives from an imported stone known as moss agate, which was also known as mocha stone due to its export from the port of Mocha (al Mukha) in Yemen, on the southwestern end of the Arabian peninsula. The stone is not actually found in that part of the world, and was imported from India and some parts of central Europe. Many of the first examples to find their way into western Europe were brought back by the East India Companies of Britain and the Netherlands. Although the appearance suggested to its European admirers that plant remains had been preserved in the stone, moss agate consists of quarts with mineral inclusions, usually manganese and iron oxides. It is not actually an agate at all.
In the 18th century the belief that the stone preserved plant remains indefinitely suggested that it had special health-preserving properties, providing good luck to the wearer. Many were accordingly turned into jewellery, particularly as polishing techniques improved, and they were often accompanied by gemstones in settings. The ability to cut the stone into thin sheets that could be polished encouraged its incorporation into various decorative objects. The Royal Collection Trust has in its collection a piece of sliced moss agate formed into the lid of a box, by Fabergé, which shows clearly how the pottery emulates the stone, and how it might be used in luxury goods. There are many similar examples.
It is thought that the comparatively humble mochaware pottery was first made by William Adams of the Greengates factory, Tunstall, England (1745-1805). Production moved to the factory of his cousin, also William Adams, at Brickhouse, Burselm and later at Cobridge Hall in Cobridge. Many English factories were soon turning out large quantities of mocha, mainly in Staffordshire into the early years of the 20th Century. Other factories were set up in Bristol, Hull, Leeds, Glasgow, Swansea and Llanelly.
Annular and mochaware vessels usually combine a limited repertoire of colours. The concentric rings include yellow, yellow ochre, blue, black and and beige. More rarely some feature terracotta, orange and green bands. The background is usually cream or white, and the dendritic design is usually blue or black. In some cases the mochaware decoration remained purely abstract, but on some vessels the acidic solution is controlled to create images representing trees. Some examples of both abstract and more representational uses of the style are shown below.
Being so inexpensive, and at the same time so attractive, it became extremely widespread. It was often used to make pint mugs for pubs, marked with an imperial symbol confirming the correct volume, and ordinary domestic items like cups, mugs jugs, jars, lidded pots and mixing bowls, and even chamber pots. It was almost never used for flat items like dishes, plates or platters. Because the patterns made could be influenced but not precisely determined, each piece was unique. Mocha and banded creamware were exported in large amounts to the United States, which was soon manufacturing its own mochaware.
On the pottery, the tendril effect of the moss agate is achieved by dripping a dark acidic colouring (which could include urine, tobacco juice, lemon juice, ground iron scale, hops or vinegar) onto the alkaline slip (mixture of water and clay) of the pot, whilst still wet. The alkaline liquid splits, and the result was thought to resemble the moss agate. Here’s a description of the technique from the University of Toronto’s Physics department:
The original recipe involves a “tea” made by boiling tobacco, which is then colored with e.g. Iron oxide. The piece is first coated with a wet “slip” (very runny clay/water mixture). Then the tea mixture is touched onto the wet surface. The acidic tea reacts with the alkaline slip and the dendrites grow quickly from the point of contact. The dendritic pattern is clearly the result of a dynamic process in which the contact line between the two liquids, tea and slip, becomes unstable. The surface tension of the tea is less than that of the slip. The instability is probably driven by a combination of capillary and Marangoni (surface tension gradient) stresses, coupled somehow to the acid/base chemical reaction. Similar looking instabilities are known in surfactant driven flows.
A decisive contributor to the production of both mochaware and annular ware was the rose-and-crown engine-turning lathe, developed by Josiah Wedgwood. There was a hefty up-front cost, but it allowed a mechanized approach to the otherwise hand-applied concentric rings of coloured slip.
Experiments described by The Ceramic Arts Network website, explain how the techniques have been used to make modern mochaware in modern experiments:
The mixture that is used to form the patterns is called “mocha tea.” It was originally made by boiling tobacco leaves and forming a thick sludge that was then thinned with water and mixed with colorant. However, nicotine solutions are only one form of mild acid; many others will work, such as citric acid, lemon juice, urine, coffee or vinegar, particularly natural apple-cider vinegar. One of these would be mixed with colorant. Most colorants work quite well, although carbonates and stains are usually better than oxides, since they are typically a physically lighter precipitate than oxides. Heavy materials such as black copper oxide, black cobalt oxide and black iron oxide do not work well, because the acid can’t adequately hold them in suspension. A ratio of about one heaping teaspoon of colorant to a quarter cup of mild acid is usually a good starting point. However, a good deal of individual testing has to be done to get the two liquids to work together to create significant dendritic formations or diffusions.
The Colonial Sense website tells how Charles Dickens visited the Copeland Pottery Works at Stoke on Trent in the Potteries:
I am well persuaded that you bear in mind how those particular jugs and mugs were once set upon a lathe and put in motion, and how a man blew the brown color (having a strong natural affinity with the material in that condition) on them from a blow pipe as they twirled; and how his daughter, with a common brush, dropped blotches of blue upon them in the right places; tilting the blotches upside down, she made them run into rude images of trees.
The sherd from my garden shows a band of yellow ochre on and beneath the rim with a beaded or rouletted design impressed into the surface below the rim, produced by using an embossed rouletting wheel. The beading was achieved by a simple cylinder attached to a handle and rolled onto the surface of the ceramic. It took a very steady hand. Some rouletting is very subtle and complex, but this is clearly not. Still, it is another decorative aspect to the vessel. A segment of black dendritic patterning is visible on a cream background, separated from the wide band of yellow ochre by a thin band of blue. It is a solid, utilitarian piece of earthenware, almost 1cm (a third of an inch) thick at the rim, narrowing into the body of the vessel. The vessel originally had a diameter of 25.5cm (10 ins), which makes it a fairly substantial object. Its walls show very little vertical curvature, unlike most mixing bowls, so it may have been a large pot of some description.
Today,whole and undamaged items of mochaware attracts collectors on both sides of the Atlantic. My sherd, though part of a fascinating story, is of course worthless. As usual, apart from trying to find out information about the odds and ends in the garden, together these objects are combining to form a sense of who lived here before and what sort of livings they may have had.
There’s a truly illuminating video of dendritic mochaware being produced by a modern artisan on YouTube, showing how the acid reacts when it meets the alkaline, as follows:
For other objects in the series,
see the History in Garden Objects page
Books and papers
Wright, K.F. 2021. Artifacts. In Loske, A. (ed.) A Cultural History of Color in the Age of Industry. Bloomsbury Academic.
Ceramic Arts Network
Mocha Diffusion Acid/Color Mixture
Colonial Sense website
Mochaware – The Hidden Utiitarian Gem. By Bryan Wright
Greengates Pottery, Tunstall
Moss agates: pictures and power. By Kathryn Kane
Ceramic – Pottery Dictionary
Royal Collection Trust
Box with moss agate panel 1903-08
St Mary’s University
University of Toronto, Physics Department
Dendritic patterns on mochaware pottery