The Mystery and Allure of Cobalt Sea Glass

Updated from version published in spring 2014 edition of Shorelines Newsletter 

Ellie Z. Mercier


Sea glass collectors can certainly relate to the jubilant sensation that transpires when striking gold. Of course, not the sought after nuggets that lured settlers west during the Gold Rush of 1849, yet smoothly tumbled specimens of the finest quality, which actually have no resemblance to gold whatsoever but are dressed in the magnificently rich hue of cobalt blue.

Many enthusiasts would likely agree that discovering prized shards of ruby red, yellow, and purple – and especially those boasting coats of orange – are surely hobby-related milestones worth writing home about. However, although true blue finds are generally more plentiful than the shades ranked as most scarce, few collectors can resist the mysterious allure of cobalt blue sea glass.

Detecting glimpses of well-worn cornflower or royal blue gems ashore may generate well-deserved shrieks of delight on behalf of some beachcombers, while others may experience a stunned silence. Yet despite the differing external reactions to such feats, collectors are often left to ponder the magical significance of the cherished shade.

Represented as the first element in the ninth column of the periodic table, cobalt possesses an atomic number of 27 and is recognized by the symbol Co. The mineral was formally discovered in 1735 by Swedish chemist George Brand, who dispelled the myth that the element Bismuth was responsible for the rich blue color of glass. However, coba

lt compounds were used for thousands of years before Brand isolated the element. Scientists have traced the use of cobalt back to the ruins of the ancient city of Pompeii and to early civilizations of Ancient China, and the mineral was also used in Egyptian art and Persian pottery. Although prior to the 1940s, cobalt was used sparingly due to the limited quantity, the expense, and the difficulty to extract the mineral. Modern day collectors often associate the shade with luminous blue medicine bottles and cosmetic jars produced during the early to mid-twentieth century.

However, cobalt’s use as a coloring agent is not limited to glass, jewelry and ceramics; the compound is also used as a pigment for paint, ink and even cosmetics. Other applications of cobalt include the production of rechargeable batteries and the electroplating of cutlery and jewelry. Rather than an element found in nature, cobalt is a hard yet brittle mineral contained in the Earth’s crust and is a byproduct of the mining of other metals, including nickel, copper, silver, lead and iron. In its natural state, the color is a bluish-white shade, similar to gray. Cobalt salts are actually the source of the brilliant and permanent rich hue associated with the mineral. The majority of cobalt is mined in Africa, particularly in the Democratic Republic of Congo (or Zaire, prior to 1997), which extracts close to forty-percent of the world’s supply annually. Other sources are found in Canada, Brazil, Russia, China and Morocco. Also, researchers believe there is a vast source of cobalt contained in the ocean’s floor, although scientists currently lack the technology to extract the element. Interestingly, studies conducted by the United States Geological Survey conclude that cobalt likely exists in the shallow waters of the Hawaiian Islands (USGS).

Ironically, among the many interesting facts about cobalt is the mysterious nature of how the color’s name originated. Long ago, superstitious German silver miners believed that malicious spirits were affecting their health as well as stealing silver ore from the mines, and they referred to these spirits as kobalt, a derivative of kobold, which is German for goblin. Other fascinating facts surrounding the element include artist John Varley’s presumption that cobalt is an ideal substitution for the shade of ultramarine blue, which was widely used for painting skies. Another artist, Maxfield Parrish, was so well known for his superior cobalt blue sky-scape paintings that the hue is sometimes referred to as Parrish blue. Cobalt was also the primary pigment used in notable blue and white Chinese porcelain, originally produced in the late eighth or ninth century. Furthermore, cobalt is used to illuminate the cornea of the eye to detect corneal scratches and is used in the production of magnets, and Radioactive Cobalt is used to treat cancer. And oddly enough, cobalt is added to the diet of sheep in order to prevent disease and improve the quality of their wool.

The outward reactions of those fortunate enough to experience such a hobby-related milestone as striking gold – or rather, witness sudden brilliant glimpses of blue jump out from the sandy canvases before them – may differ significantly, but few sea glass collectors can resist the powerful allure of cobalt treasures, which in many aspects, are truly gifts of Mother Nature.

Photos: Ellie Mercier

  • Ellie found the frosty marble in the Abacos (her first marble find & she remembers that she was extra excited because Richard LaMotte shared that cobalt marbles are more rare than red marbles).
  • The bottle is from Ellie’s bottle collection – She also collects antique bottles.
  • Ellie found the jar lid in the Chesapeake Bay (almost a decade ago)
  • Yet most interesting is the image of the large cobalt shards, which Ellie found following the 2009 festival in Lake Erie…One of her customers took me combing along the river in nearby Conneaut, Ohio, where much slag glass was discarded in the 1960s by the GE Light Bulb Base Plant (these are huge, and the hue is extremely vibrant, alike bright violet).

Genuine, Artificial and Altered Sea Glass

“When any true item becomes of value, a faux or artificial product is not far behind.” –Mary Beth Beuke “Genuine Vs. Artificial Sea Glass: Why It’s Important

It is the mission of the North American Sea Glass Association (NASGA) to educate collectors and consumers about pure, natural sea glass. NASGA requires that its commercial members “leave sea glass in its natural state and do not create imitation sea glass; meaning that the sea glass will not be altered by, acid etching, sand blasting, tumbling, or by any other means so as to artificially replicate genuine sea glass.” This article is provided to provide information to consumers in order to help identify some of the differences between genuine, imitation and altered sea glass.

At the North American Sea Glass Festival and certain other festivals where noted, only genuine sea glass is allowed. At some events, craft glass and other altered sea glass is used and it is up to the consumer to determine what they’re buying.  NASGA feels our commercial member artists who create only using genuine glass can’t compete with those using those much less expensive materials. Ideally, as long as vendors at various regional sea glass and coastal festivals don’t label their items “pure,” “genuine,” or “wave-tumbled” sea glass it’s not a huge problem because essentially they can use any materials they want. But consumers should know what they’re buying. Sometimes it can be easy for people to tell the difference between real or tumbled glass, and sometimes it can’t, especially online.

The number in manufacturers of artificial sea glass has grown in recent years as demand for pure sea glass has increased and its supply has dwindled. Beaches are overpicked, with more and more people hunting for sea glass. Entire businesses have been created in which “sea glass” is being created nowhere near the sea by savvy individuals with a good working knowledge of what real sea glass should look like. Some of the manufacturers of eco-friendly or “green” glass very clearly label their product this way and make it clear to consumers that what’s being purchased is not glass from the sea, and some do not.

Many producers trying to pass off non-genuine sea glass as real go to a great deal of trouble to make the counterfeits look natural. Unlike the rock tumblers of the past that made fake glass easier to spot, they’re using advanced tumbling, sandblasting and acid-washing processes that give glass a similar appearance to real sea glass, and buyers think if they see the “c” marks and white-coated “frosting” layer on glass, it must be real, and this isn’t always the case. Sometimes manufacturers purchase vintage glass (including marbles, perfume stoppers or figurines) from antique stores or other venues and put the glass into cement mixers or even cages in the ocean and let it tumble around for a period of time, then sell it online in Facebook groups, Etsy shops and on eBay as real sea glass.

Feeling the glass in your hand is often the best way to tell real from fake because textural differences in the surface make the consistency of genuine sea glass in your hand nearly impossible for a machine to reproduce. The depth of the pitting in the surface of genuine glass is something that goes nearly to the center of the glass that historically spent time in the body of water; while in a tumbled piece, only the surface has been made smooth, leaving a shallower appearance to the glass. Real hydration over time in a natural body of water in random wave patterns will always leave a different finish on a piece of glass than anything a machine or artificial process can produce.

Unfortunately, people are spending a lot of money on fake sea glass at shows, in shops and online every day and may not know the item they have purchased is not genuine sea glass. Here are some things to consider.

Signs the “sea glass” you’re buying might be fake:

  1. Does the seller keep selling similar batches of the same rare styles and colors and shapes of glass over long periods of time with hundreds of sales? No beach in the world produces endless hundreds of pounds of rare colors in repeated jewelry quality perfect shapes and sizes.
  2. How trustworthy is the seller? Did they beachcomb the glass themselves or purchase it from another party? Do you know them personally? The sea glass community is small enough that if you want to buy, often someone can point you in the right direction (whether it’s a Facebook group or reputable eBay seller known by a friend) without having to buy from complete strangers. Only buy from people you trust. This is simply the best way to know you are buying genuine glass. Reviews on eBay and Etsy are not always the best way to get information, since people have been buying fake glass and not knowing it for a long time from many sellers.
  3. If you’ve bought a piece you suspect is fake, does it feel unusually smooth compared to other pieces in your collection? Sea glass often has a rougher texture to it after tumbling in the ocean. Fake glass is more likely to have an odd perfect satiny sheen on it. However, this can often depend on which beach it comes from as sea glass surfaces depend on ph levels in the body of water. For example, sea glass from different parts of the world can have a more satiny sheen. There is still a difference between the finish in the glass from these beaches and the glass a machine tumbler produces- the main clue being the similarity in shape and size and color across batches. So texture can be one clue to determine genuine glass, but is not always the best one since some beaches do produce silkier glass. If you hold a handful of genuine glass in one hand and a handful of tumbler glass in the other, you can feel the difference in a very clear way. At NASGA’s annual show, educational samples showing the difference between genuine and manufactured glass are available to help you learn the difference.
  4. Another way to spot sea glass that’s been in a tumbler is tiny diamond “glints” on the surface. If you turn the piece in your hand, often the tiny “cuts” will catch the light and will reflect in a diamond-like glinting fashion that pure sea glass generally does not. (This feature can be found on genuine sea glass sporadically because of the way it broke in the surf, but if you are holding a handful of fake glass, you can find these glints consistently across the pieces).
  5. It is very difficult to tell genuine from fake glass, especially in photos. Knowing your seller (and whether they have beachcombed the glass themselves or know exactly who did) is key! Keep in mind that when you buy sea glass from North American Sea Glass Association members, you can be certain they are required to sell only genuine sea glass, so ask if the seller is a member of NASGA.

In addition to manufactured fake glass, other methods are used to alter sea glass from its original form. Some are allowed by NASGA as part of our commercial memberships and some are not. For example, the drilling of sea glass in order to create a jewelry piece is not restricted, because this method is used by the artist in order to create the piece of jewelry and it is also clear to the consumer that a hole has been drilled, so no effort to cover up the alteration has been made. Similarly, some artists paint on top of the surface of sea glass in an artistic manner. For example, artistic renderings of sea life are depicted on the top of a piece of white sea glass. This is also allowed since the alteration of the sea glass is clear to the consumer purchasing the art piece.

A newer method of altering sea glass called “colorization” has entered the industry in which sea glass is permanently altered using a chemical process from the backside of a piece of white sea glass (see photo on the left), which is then placed into a bezel setting and sold as genuine sea glass. Also “staining” (see two photos on the right) sea glass is taking place where the color of white sea glass is changed in a dyeing process. It is the opinion of NASGA that since the color is being presented to the consumer as an “illusion” this violates our guideline that commercial members should “leave sea glass in its natural state and not create imitation sea glass”and that “sea glass will not be altered by …any other means so as to artificially replicate genuine sea glass.”  These artificially created colors have the potential to confuse consumers both at sea glass shows and online since in a bezel setting or (with staining) even loose, individuals cannot tell the difference between genuine and artificial colors, especially when natural sea glass colors are being replicated.

It is the opinion of NASGA that sale of colorized sea glass undermines sale of genuine rare and common sea glass colors by artisans and sea glass hunters who obtain these colors in natural bodies of water and that this glass should not be labeled “genuine” since it has been permanently, irreversibly altered and therefore does not represent genuine colors found in glassmaking history.

Beer and sea glass bottles in Wilmington, Delaware

The 12th Annual North American Sea Glass Festival will be held on Saturday, September 23, 2017  and Sunday, September 24, 2017 at the Chase Center on the Riverfront in Wilmington, Delaware along the revitalized Christana River waterfront.     Wilmington is a city in Delaware on the Christina and Delaware rivers. Downtown’s early-20th-century DuPont Building is part of the local DuPont family legacy, which is also evidenced at the Hagley Museum. Those grounds include the 1802 DuPont gunpowder works and the family’s Georgian-style home. The Old Swedes Church, between the Christina River and Brandywine Creek, is from 1698.  European settlement had begun with the arrival of the Swedes and Dutch in the 1630’s and were the first European settlers in the Delaware Valley.

This year the North American Sea Glass Festival is excited to take place in one of the first locations in the United States to brew and bottle beer.  Why is this fun fact relevant to our festival?   Because as all sea glass collectors know, beer bottles and their colors, clear (white), amber and green are still plentiful to find and still makes sea glass collectors happy to find, even if they are considered sea glass common colors.

Here’s some interesting information and excerpts from Delaware Beer History about the history of beer (and bottling!!) in Wilmington, Delaware.

“Brewing began in Delaware with the arrival of the first sizeable European settlement.  Shortly after establishing a trading fort, Fort Christina, at present day Wilmington in late March 1638, Swedish and Finnish settlers immediately began making preparations to grow barley and locate hops for brewing beer.  Beer was a staple of the European diet in the 17th century, as it was recognized as the healthful alternative to drinking water.  Back in their native homelands, water supplies were often polluted and unsafe for drinking.  Of course, they had not yet discovered that boiling  during the brewing process killed bacteria.  Ale was consumed throughout the day by men, women and children, though the latter two groups tended to be served drink with a lower alcohol content.”

Bavarian-Luxburger label (John Medkeff collection)

Skip ahead a few hundred years and prohibition stopped beer operations in America.  However, one of Delaware’s beer pioneers, Carl H. Eisenmenger maintained ownership of Wilmington’s Bavarian Brewery at 5th & DuPont Streets.   “Eisenmenger, who understood that Prohibition would likely soon be a reality, had began brewing a ‘near beer’ cereal beverage as early as 1918.  In 1919, the Bavarian Brewing Company officially changed its name to the Peninsula Products Company, Inc.  The company continued with its Quex ‘near beer’ product and added a line of soft drinks.  After an initial surge in business, the venture ultimately failed and, in 1925, Peninsula closed its doors for good.   Eisenmenger, who maintained ownership of the 5th & DuPont property, rented the complex to other soft drink companies and businesses.  He temporarily withdrew from the beverage industry but would return again to revive brewing operations after repeal of the 18th Amendment.

When Repeal came in April 1933, Eisenmenger immediately formed a stock company and began working on plans to revive the brewing business.   Delaware granted Bavarian-Luxburger the state’s first post-Prohibition brewery license on September 1933.  After securing a Federal brewing license a few weeks later,  the company began production.  On November 27, the first cases of bottled Bavarian Beer finally left the plant.”

Read more Delaware Beer History here>

After the North American Sea Glass Festival, meander along the Christina waterfront to find modern day craft brewers to quench your thirst, such as Iron Hill Brewery, located a short walk from the Chase Center on the Riverfront.

View a map of the Wilmington Riverfront here>

Hartmann and Fehrenbach Brewery, had its origins with the “Father of Lager Beer in Delaware”.  The year 1890 also saw the Hartmann & Fehrenbach Brewing Company expand their operations into bottling,  which were beautifully embossed with the company’s logo, the mythical winged stallion, Pegasus.

While other regions in America have been better known historically as centers of beer production, few have been brewing as long as Delaware brewers.  For nearly four centuries, First State brewers have been producing high quality, award-winning ales and lagers.  Explore the state’s fascinating and, until now, largely unknown brewing history on this site and in the pages of the book Brewing in Delaware by John Medkeff, Jr.

More fun facts about beer history and how to date bottles:

“Until the late 1800s, most beer was sold in kegs since bottled beer had to be consumed quickly or it would spoil. But the advent of pasteurization in 1876 made it safe to bottle fermented products, and along with America’s growing rail system, the bottled-beer industry boomed.

In the early 1890s, Congress passed taxes on bottled beer, along with legislation allowing companies to bottle their brews onsite and bypass an archaic process of barreling, transporting, and packaging their drinks into bottles elsewhere. Prior to this action, beer bottles often featured a bottling credit on them in addition to the name of the brewer, which is one way to date a beer bottle. While early beer bottles came in a variety of glass colors, including brown, blue, green, and clear, the first American bottles were made from ceramic stoneware. This style was often used for dark beers like porters and stouts or non-alcoholic drinks like root beer or ginger ale.

Since bottling was costly, many early containers were embossed with a company’s name to help ensure their safe return, although this didn’t deter bootleggers from reusing them. At the time, many would-be brewers made their products out of their homes and used their bottles for multiple beverages, so some of these embossed bottles never even included the word “beer” on them (the brewer’s company and city names were all a customer needed to know). As these fledgling enterprises grew into mature companies, though, phrases like “Brewing Co.” were added. Less common embossing features included a company’s phone number and graphic icons like animal mascots. William Painter’s invention of the single-use “crown cap” in 1892 sealed the deal for mass-produced beer bottles. The innovative design, with its crimped edge and cork lining, overtook some 1,500 different styles of bottle stoppers used prior to 1892. The crown cap also led to more uniform, machine-made bottles.” – Collectors Weekly

Have you found old bottles, beer, soda, liquor, medicines?   The body of a bottle has an assortment of characteristics or diagnostic features that can assist a person trying to date or at least tell a more complete story of a given bottle.  Learn how to date your bottles on the Society for Historical Archaeology website here>

Happy hunting!

Excerpts in this post from and 

Find out more about the 2017 North American Sea Glass Festival in Wilmington, Delaware here>

North American Sea Glass Festival 2017 lectures announced

North American Sea Glass Festival Lectures to be held Saturday, September 23, 2017
Wilmington, Delaware, Chase Center on the Riverfront

Fake Versus Genuine Sea Glass Across the Globe
Richard LaMotte and Mary McCarthy
11:30 a.m.

Buyer beware! With all the fake sea glass for sale online, how can shoppers tell the difference between fake and genuine sea glass?  This lecture by NASGA founder Richard LaMotte and the current NASGA Education Chair Mary McCarthy will describe how consumers and collectors can distinguish the difference between genuine sea glass and fake sea glass, including an exhibit of sample fake sea glass.

Richard LaMotte is the author of the award-winning book Pure SEA GLASS and a recent sequel titled The Lure of Sea Glass. He was a co-founder and past-president of the North American Sea Glass Association.  Richard works in Chestertown, Maryland and lives in southeast Delaware. He and his wife Nancy started a Chesapeake Bay sea glass collection for her jewelry business in 1999. In 2002 he began researching glass history for a lecture which led to extensive research into glass colors, as well as the physics and chemistry behind the frosted glass forms found along the shoreline.

In 2006 Pure Sea Glass was awarded first place for non-fiction in Writer’s Digest 13th Annual Self-Published Book Competition.  Richard and his book have been featured in The Washington Post, on Martha Stewart Living TVCoastal LivingParade Magazine, Baltimore SunThe Boston Globe, Delaware Beach Life, on NPR and Maryland Public Television.

Bestselling author Mary McCarthy is a lifelong journalist whose career includes a number of national and regional newspapers, magazines and websites. She lectures at the University of Maryland’s College of Journalism and is an instructor at the Writer’s Center.  Mary serves on the Board of Directors of the North American Sea Glass Association where she is also Chair of the Education Committee, speaking regularly at beachcombing conferences around the country. Mary is a mother of four on Maryland’s Eastern Shore where she enjoys kayaking and beachcombing. She is the founder of SeaCrate, an ocean-themed monthly subscription box service and is currently working on a beachcombing memoir.

Amazing Journeys: Glass Fishing Floats, from the East and the West
Dr. Deacon Ritterbush (aka Dr. Beachcomb)
1:30 p.m.

A life-long beachcomber, Dr. Deacon Ritterbush (aka Dr. Beachcomb) is an award winning author (A Beachcomber’s Odyssey) and founder of the annual International Beachcombing Conferences. She lectures throughout North America on sea glass, pottery shards and the archaeology of beachcombing. To learn more about her or about beachcombing, visit Dr. Beachcomb on Facebook, Instagram and

Her lecture at the 2017 NASGA Sea Glass Festival will focus on fishing floats from the east and west, including their practical and spiritual aspects as well as the amazing sea glass shards resulting from their breakage.


What Makes Sea Pottery Regionally Distinct?
Connor O’Brien
3:30 p.m.

Lifelong beachcomber and avid collector Connor O’Brien will discuss his experiences beachcombing and investigating sea worn artifacts that were collected during his international travels and correspondence with beachcombers around the world. The topic will be sea pottery, with an emphasis on factors that make sea pottery regionally distinct. Attendees will enjoy one of the largest showcases of sea pottery to date, handle exotic shards from around the world, as well as learn the skills required to identify and date sea pottery. Viewers should expect to walk away with an increased appreciation for the aesthetics and history of sea pottery as well as an eagerness to take a closer look at their own pottery finds.


Beachcombing Stoneware Sea Pottery

by Connor O’Brien

The majority of sea glass originates from mass produced utilitarian vessels, while tableware and art glass are less common sources. The same can be said about sea pottery. Yet due to the immense variety of ceramics, identifying sea worn fragments can be particularly challenging. A good way to start is by classifying shards into one of three categories: earthenware, stoneware, or porcelain. Ceramics are grouped into these categories based on the density and firing temperature of the clay. The clay mixture and body of a ceramic is referred to as paste, whereas the surface coating is known as glaze. Grouping ceramics by paste type is the first step in identifying the origin of a shard, and learning to distinguish different pastes and glazes is crucial to making accurate identifications. (Figure 1)

Figure 1. A small representation of earthenware, stoneware and porcelain. All three types are variable in color, appearance, and texture, so the best way to identify them is to learn the feeling of the differences simply by handling them.
Top row: Red earthenware fragments, brick and terracotta. The color of earthenware can range from cream white to red, dark gray or tan, depending on minerals in the clay used. It is distinguished from stoneware and porcelain by its relatively low firing temperature, porous and less dense paste.
Middle row: stoneware jug fragments. Stoneware is nonporous, hard and compact, fine textured but not glassy like porcelain. It requires a medium to high firing temperature but does not need glaze to be watertight. However stoneware is often glazed with salt or decorative slip glazes. Slip glazes are glazes comprised of clay in water, applied by dipping or washing the ceramic vessel.
Bottom row: Porcelain fragments distinguishable by the very hard dense body, vitreous nature and white color. Porcelain can be glazed and decorated in a variety of ways.

Investigating traditional and regionally relevant ceramics is a great place to start when studying sea pottery. Understanding the history of production is also very helpful when it comes to identifying and dating shards. For beachcombers in North America, especially those on the shores of the Great Lakes and east coast, stoneware is a common source of sea pottery because it was once popular and locally produced. With basic knowledge of vessel shapes and glaze types it is possible to know the origins of these stoneware fragments, despite the fact that they are highly altered from their original form. An immense variety of products were available in stoneware, the most common being jugs and pots. Learning to recognize the characteristics of these forms is another important part of identifying sea pottery. (Figures 2-5)

Figure 2. Stoneware sea pottery with distinct features.
Top Row: Decorative cobalt glaze applied to an incised design. Decorative cobalt glaze applied with a sponge, known as spongeware. Decorative cobalt glaze applied to a sculpted pattern. Decorative dot band applied with a rolling tool.
Middle Row: Slip glazed shard exhibiting pop out, a defect formed during the firing process. Slip glazed shard from a jug neck, the curve of the neck influences how the glaze is weathered. Slip glazed shard with concentric lines, small surface ripples left by the potter influence the exposure of glaze to abrasive forces.
Bottom Row: Dark colored Albany type slip glaze, the use of this glaze can date shards as early as 1860. Boarder between Albany type and Bristol type glazes, use of both glaze types dates shards before 1915. Light colored Bristol type glaze, use on both the interior and exterior dates shards after 1915. Note that these dates are approximate generalizations not strict limits.


Figure 3. Stoneware jugs are arguably the most common source of stoneware sea pottery. These containers were made in many capacities and styles, and used for storing and selling liquids in bulk; they commonly held molasses, honey, syrup, vinegar, liquor, cooking wine, and chemicals. Similar to glass bottles, stoneware jugs have many features that can provide identifying information, such as the handle, shoulder, closure, and base. One jug may produce dozens or even hundreds of sea pottery shards, and a single shard can be used to make an accurate identification. Stoneware shards can also be confidently matched by paying close attention to paste and glaze. The shards pictured here undoubtedly originate from the same jug. Although found at different times, each occurred in the same area of the beach and have a distinct feel and appearance that suggests a shared origin.


Figure 4. The mark of a twisted wire pulled in a loop in order to cut the vessel from the wheel. Subtle markings such as this can be used as clues to gain information about the shards origins, as well as the processes used to create it.


Figure 5: Squeezed clay lines resulting from clay being compressed into a mold, an indication that the original vessel of this shard was made by mold.

Stoneware ceramics in North America began with immigrants from Germany, England, and France who brought the craft over seas in the 17th and 18th centuries. Colonists continued to import English and German stoneware well into the 19th century, yet over many generations of master and apprentice, ceramic artisans blended old world techniques and styles to develop a distinctively American variety of stoneware. The earliest American stoneware was made from scratch in small batches and distributed locally. These ceramics were often plainly salt glazed, crudely shaped, and occasionally decorated with cobalt motifs. The nature of ceramics allowed for artistic expression, stoneware creations were individually handmade and often intentionally embellished with a personal touch. For these reasons collectors regard 17th and 18th century American stoneware as a folk art. The uniqueness and relative scarcity of these vessels make them a rare source of sea pottery that is difficult to trace. (Figure 6)

Figure 6. The appearance of plain salt glazing is often compared to the texture of an orange peal. The color of salt glazing is variable but commonly brown or gray. Plain salt glazing typically dates shards prior to the 20th century. This shard originates from a salt glazed ceramic water pipe, which was a common form of plumbing and drainage throughout the 19th century.

Potters’ firms and their networks grew alongside the development and expansion of the United States. By the 19th century utilitarian stoneware was an essential part of everyday life and potteries were established all across the country. Potters were able to obtain better and more consistent materials, improve their shaping techniques, as well as distribute their wares beyond local communities. These advancements, paired with the increasing demand for American stoneware, lead to a transition from small family businesses to unified potters’ firms. Individuals who specialized in specific tasks of an assembly line began to replace the tradition of master and apprentice. By the turn of the 19th century, the demands for American stoneware were met by the mass production of simple and uniformly slip glazed vessels commonly known today as crocks or crockery. (Figure 7)

Figure 7. Stoneware vessels typical of the late 19th century and early 20th century. Markings such as words, stamps, and capacity numbers can be used to help make precise identifications. Drips from the slip glazing process are indicative of the dipping used to apply the glaze. The combination of Albany type interior and upper exterior with Bristol type on the bottom exterior was a fashionable design that declined in popularity after 1915.

The quantity and consistency of mass produced vessels is what makes them common and identifiable. Glaze type can be used to date stoneware to a relative era (Figure 2). The iconic two-toned stoneware with brown Albany type glaze on top and white Bristol type glaze on the bottom began to replace plain salt glazed stoneware during the mid 19th and early 20th century. By the 1920’s, stoneware glazed entirely in white Bristol glaze was favored for the sanitary appearance and easy to clean surface. The great depression effectively ended the era of American stoneware, though it has been continually produced, it can be assumed that most fragments of stoneware sea pottery are near or over a century old. With basic knowledge of these ceramics even ambiguous shards are relatively identifiable. When dating sea found shards, the context and history of the beach is equally important as the history of the fragment and may help provide a more accurate identification. A perfect way to display these beachcombed shards is to store them in a stoneware vessel, such as an open container. (Figure 8)

Figure 8. A perfect way to display stoneware sea pottery is to store it inside a stoneware container. Adding a false bottom using cardboard and covering it with a thin layer of shards is an easy way to make an attractive display. Stoneware pots come in many forms and sizes and also make a good depository for storing shards in bulk.


Works Cited: Greer, Georgeanna H., Chris Williams, and Tina Griesenbeck. American Stonewares: The Art and Craft of Utilitarian Potters. Exton: Schifftler, 1981. Print.

Connor O’Brien lives in Maine and is a college student and an avid sea glass and sea pottery collector.