Precursor Light Industry in Support of the Jamestown Glassworks: Potash, Charcoal and Lime Production


By: Rick Orli                                                                                                  April 5, 2006

(c)2006 Richard J. Orli 


Polish and other Central European workers came to Jamestown in 1608 and subsequent years, most of whom were skilled craftsmen in selected target industries such as glassmaking and lumber.  This article outlines an approach for interpreting master glassworks craftsmen in the process of establishing an industry.  We are not planning to set up a glass factory, which has been done 'next door', but instead to describe efforts to build the several types of necessary supporting light industry to make charcoal, potash, and lime, and find the right kind and quantity of raw materials - all precursors for the glassmaking process.

Glass Technology Background

To make glass, you need the ingredients.   First is quartz sand, silicon dioxide (SiO2).  However, pure silica has a melting point of about 2000 Celsius which is difficult to achieve using 17th C. Technology.  

The addition of a flux lowers the melting point to 1000 C.  The flux could be sodium carbonate ‘soda’ but given the resources at hand in Jamestown would almost certainly have been potassium carbonate, or potash.

However, the potash makes the glass soluble, so lime (calcium oxide, CaO) was added to restore insolubility.

Sand, lime, potash, additives for color, and heat are the 5 basic ingredients of glass.

·        Sand can be beach sand, but that often has too many impurities.  Famous glass centers of the world usually have access to mines that contain nearly pure quartz sand.  Harrington in “Glassmaking at Jamestown” thought the sand was from local beaches.  That’s good enough for me (but that would have not done if they ever had a serious factory running, which they never really did).

·        Lime or quicklime (calcium oxide) is made by heating ‘calcining’ oyster and other shells.

·        Potash is derived from wood ash, and is discussed in more detail below.

·        Additives for color include various salts of magnesium, copper, iron, etc.  For example, natural quartz sand usually contains some iron which yields a green glass.  Adding a small amount of magnesium clarifies the color, adding more makes purple.  These additives are optional and used in small quantities and so were probably initially brought from England, if they were used at all.

·        Heat comes ultimately from wood, lots of wood.  However, attaining consistently high temperatures is difficult with wood that might be imperfectly seasoned; therefore, a supply of charcoal was necessary to guarantee that the necessary temperatures could be achieved reliably.  I can imagine that the fire would be started with wood, and then a quantity of charcoal would be added to elevate temperatures until the melting was well progressed, at which time the fire would be maintained primarily with wood, supplemented occasionally with charcoal as needed.  Charcoal is also a wood product, discussed in more detail below.  For that mater, seasoned wood is also a product that requires a great deal of work and planning.  Well-split wood takes 6 months (or better, a year) to dry, and it is best if the final month or two before use is spent in a dry shed.  

No one  knows where the glass making formula was invented, but it was within the Roman world thousands of years ago, and Persia and Afghanistan perhaps 500BC.  How someone discovered that lime, for example, was needed is a fascinating mystery that has various legends associated with it. 

One of the earliest recopies for glass in recorded in central Asia.  The formula was still in use recently, and is documented in a documentary by Corning Glass museum, called the Glassmakers of Hera

ingredients are only two:
-    a white stone collected from the riverbed that has a fine grain with shiny bits.  This has both silica and lime, and is almost iron free.  This is ground into a white powder
-     Ash from a few species of desert shrubs.  These have a high salt content and the ash is sweat-tasting.  The shrubs are burned in a sand pit and form dense rock-like clumps of ash.
There is an interesting legend surrounding the Roman discovery of soap making, although quite possibly the Celts and others invented soap either first or independently.  The legend: soap was first discovered by women washing clothes along the Tiber River at the bottom of Sapo Hill. The women noticed the suds and that clothes became cleaner with less effort.  The cause was the ashes and the grease of animals from the sacrificial fires of the temples on the top of Sapo Hill mixed with rainwater, making soapy water which ran down a certain stream.  Saponification, the chemical name for the soap making reaction, bears the name of that hill in Rome.

Chemical tests have shown that there was a very complex mix of stuff in the Jamestown archeologically recovered glass, which supports at least the use of rather impure raw materials… such as local beach sand.  Also, there was an unusually high amount of lime in the glass, 25% or so, which makes a glass that is rather hard to work.

Harrington thought that they may have added ash directly to the frit, (the initial melting and fusing mix) and bypassed making potash, presumably to save the work in making potash,.  Maybe, but I reject that theory for now.  First of all, it is known that making potash as one of the specific industries created at Jamestown, and was shipped to England in 1608 as part of the first ‘tryal’- so they should have had an ongoing process going to crank out potash.  Second, I have no first hand experience making glass, but from my chem lab and cooking experience, somehow I doubt it.  I know they needed scrap glass ‘cullet’ to form a liquid pool as sort of a starter, to encourage other stuff to melt.  Starting a batch fritting may have been a tricky thing, and adding a bunch of crap like a couple of big scoops of ash seems extremely unhelpful – the dry ash would have acted as insulation to keep stuff from melting.  Maybe, if there was a superabundance of heat, it might not have mattered much, but it took work and probably a big supply of charcoal (which took even more work to make) to get the really high heat that would have needed.  Or, I could see adjusting the formula of a melted pool of glass by adding ash directly, but not so much that could not be stirred in without affecting the liquidity of the whole pool, and then there would have been a lot more non-melting material floating in it as scum and dregs  He also argued that the ash would contain some of the lime needed, but that could not have even begun to approach the 25% by weight of lime in the finished glass.

Potash (in 17th C.  context of a glass additive, just “salts”)  

Potash may be differentiated from Soap-ash

In ancient times, as today in certain parts of the world such as Africa, clean white-gray wood ash, also known as soap ash, was used with water to wash hands, scrub pots, and polish metal. Sometime the term soap-ash is used casually as a synonym for potash.  Of course soap-ash has little value and potash has high value; nevertheless, soap-ash was a baltic export.  The colonists may have shipped a quantity of wood ash, although it was rather a sign of desperation to ship something, anything, of any value.

Potash uses ashes from wood, lots of wood (a few tons of wood yields a pound or less of Potash). Ash can be recovered from the typical 'slash and burn' agriculture (just have to make piles of hardwood trees, ignite) and recycled from fireplaces. 

You need hardwoods to make potash as pine has very little potassium in it.  That's why it never took off as an industry in VA, despite efforts during the next century, but there was enough hardwood around in 1608 to make enough for the glassworks. 

The first stage leaches out the soluble potassium and sodium salts, by dissolving them into water.  Home lye production typically used barrels with small holes drilled in the bottom, which is covered by a filter of straw.  Then the load of ash is added.  Water is then dribbled over the ash very slowly, making lye, which drips out the bottom.  Industrial potash manufacturers usually used special-made hoppers that were sort of rectangular cones; however, I would think Jamestown would have been happy using the many available recycled barrels.  Some sort of automatic slow-drip feeder seems necessary in an industrial operation, perhaps a canvas-bottomed 2.5 gallon bucket that drips out a half gallon per hour.  Another variation is to have a leaching vat - troughs or half barrels to soak ash – from which the liquid lye is later pressed and filtered.  (Pictures of various ash leaching gear from “Making Lye from Wood Ash”  The first shows a bottom-less barrel on a stone base, scored to provide a channel for the lye drip (the ash sits on a compacted straw ‘filter’).  The second is a hopper.) Note that this gear would have to be kept in sheds or otherwise covered over to prevent rain from interfering.  The third picture is a conjectural industrial setup.  Two barrels feed one lye bucket.  Each barrel is fitted with a slow drip feeder consisting of a 2-3 gallon canvas bucket, since a steady slow feed will produce the most consistently good product.  The 2 gallons will drip in over a 5-6 hour period, so is refilled 4-5 times per day.  The Lye bucket is emptied twice per day. Two or three of these will represent a substantial lye-making capacity that will keep a large potash reduction cauldron fed most of the week.

If you are making soap, the lye solution is what you need, so you are done.  

To make potash, the lye is reduced (heated to evaporate) in huge cauldrons to make a paste which is spread out to air dry in cakes, which I think are crumbly enough to crush into powder with little effort.  It can be further processed to make a more pure, whitish, product.  For glassmaking, I don't know how much purity is needed - it seems to me that when I saw the Corning glass museum video with the Afghans making homemade glass that after they melted the sand, potash and other stuff there was a bunch of scum to skim off the top and other stuff sank to the bottom - however, some impurities might discolor the glass, maybe it depends on what you are making.

Potash and lye has other uses than glassmaking.  Besides being a key ingredient in soap, mentioned above, potash has application in leather tanning and other chemical processes.  It is also used agriculturally.  It had sufficient value to be exported back to England, and was itself one of the trial products.  

Potash from various plant materials was the only source until the first half of the 19th century, and the invention of the LeBlanc method of obtaining caustic soda, a sodium based alkali, from a brine solution was implemented on the industrial level.


To make charcoal in the field, you need to cover a huge wood pile in a cone of sod or earth to control oxygen flow; usually this incorporated a pit or a sort of half-cave dug into a hillside, to simplify the work. Controlling oxygen flow over a two day period is everything: too much oxygen you get ash, too little and it stays wood.  There is excellent archeological evidence showing how charcoal was made in medieval and early modern times in England.

Charcoal was also needed by the blacksmiths, so quantities would have been produced at Jamestown.


Lime is made by ‘calcining’ (heating to about 900-1000 C.)  shells or limestone to make quicklime, or calcium oxide.  Jamestown had the oysters and other shells in abundance, and oyster shells seem to have been the prime source of lime throughout the colonial period and even up to the end of the l9th C.  . 

The other ingredient is obviously trees for wood to make the fire.  Calcining actually works well with fairly fresh cut wood fuel, because the moisture released as it burns aids the process.

The illustration is of an ancient calcining kiln, of a type that was used from before 2000 BC up to the 18th C around the world. It consists of a pit lined with stone, into which led a ventilation tunnel.  The shells would be stacked around the perimeter, and fuel in the center.  Additional fuel could be added from the top, or perhaps via the ventilation tunnel.  The fire would be kept burning for several days.  The pit would be partially dug up to remove the lime produced.  This would have been the likely method at Jamestown for the first years; although other expedient if crude methods are know to work, such as building a large stack of several layers of alternating wood and shells. Four lime kilns have been found at Jamestown, ranging from a simple partially lined pit to a finished brick structure.  Some of these are clearly intended to efficiently partially calcin oystershells for building uses, rather than achieve pure quicklime.  The earliest brick kiln found is also essentially an unlined pit.

I wonder, given how short Jamestown must have been on labor and other resources, if a way was not found to combine efforts whenever possible.  For example, to use part of the glass kiln to serve as a calcining space – this would have produced only small quantities of lime, but perhaps a fair percentage of the glassmakers’ needs.  Also, stacks of shells could have lined charcoal making kilns, although the heat in charcoal making might have been insufficient to penetrate into a deep mass of shells.

There is archeological evidence that lime was prepared as a building material (plaster, etc.) at Jamestown, in addition for its use in glassmaking and other industry.


As a prompt for  'what the heck is that' questions from visitors, maybe we can build an impressive woodpile as a sort of precursor to making charcoal and /or potash.

And /or, a barrel can be set up, representing a lye leaching barrel, with a supply of ash. Lye should not actually be made because it is caustic and hazardous.  Large metal cauldrons to reduce the lye.

Otherwise typical lumber working tools, or in the background, glassmaking tools.  Glassmaker’s tools for use in early stages include small but long-handled fritting rakes and hoes (used to stir the ingredients before and as they melt), and clay/earthenware fritting or glass-melting pots  (heavy flat-bottomed pots, 15-17 inches wide, 10 inches high, two inch thick bottoms, 1 inch thick sides).  

Clapboard, Wainscoting, Deal (softwood boards) and other Millwork

I expect the German millners to have a sawmill at least, such as:


13th C. Up-and-down sawmill,  Sketch-Book of Wilars de Honcote

Other mills illustrated in Kunstliche Abrisz allerhand Wasser- Wind- Rosz- und Handt Muhlen and Zonca, Vittorio Novo teaitro di machine et edificii per uarie et sicure operationi  

However, most woodwork would have been through riving (splitting, e.g. with wedges and froes) lumber, including the preparation of clapboard. A saw would be used to crosscut rather than rip wood. See the following two resources:

http// 17t C frame building construction.

http// 17th C furniture making and riving   

Clapboard production does not require mill machinery; it can be efficiently produced by riving.  However, a mill-powered cross-cut saw would help speed cutting sections into correct lengths.  A rip saw mill would also be useful of course, especially for woods such as elm that won’t rive, or for wood that has seasoned. Wainscoting in the 17th C. was essentially planed clapboard, so perhaps the pieces that came out nicest got the additional finish.


The sort of fancy trim goods and moldings we associate today with millwork had not been invented by that day.  However, compound planes were used to shape and finish rails and simple moldings.  Sometimes, larger planes were pulled with the assistance of a drogue wound by a mill.


They would necessarily have brought the mill with them, with most parts prefabricated.  A mill requires special parts made of seasoned wood of the appropriate type: elm for hubs, pear or apple for cogs, ash for torsion beams, etc.  All properly seasoned months or even years.  A large water powered mill requires an axle that is up to 2’ diameter of a wood such as oak: a piece this massive would take 6 years or longer to season.  The Jamestown crew simply could not have constructed a mill with local materials except for some frames and other less-important structural pieces.


My first attempt, I had a cauldron reducing the lye into potash behind me, a set of barrels set up as a lye leaching station before me, while I worked on making a fritting pot.  That proved to be an effective means of starting a conversation about the fact that there is an awful lot I need to do as a master glassmaker before I get to the sexy artistic glassblowing stage. 

e.g., “I’m a master glassmaker from Poland, and as you can see I’m not blowing glass, but I am making one of the tools of my trade – a fritting pot.  We break pots when we work, and when the ones we bring from England are gone we have to use the ones I am making today.”  A fritting pot is where I mix the sand potash and lime, so I could start my description of how all those ingredients are made by us, and except for sand they all involve chopping down trees.

Trees for ash for potash, trees and pits for charcoal, trees and pits for calcing oystershells for lime, more trees for wood fuel. After a while, it becomes clear to the listener that I spend most of my time as a ‘glassmaker’ cutting down trees and digging big pits. At least the gentlemen are useful for chopping down trees.


We plan to wear standard western clothing of the period with attention to a few specific details.  Craftsmen typically wore aprons and over-pants or slops.   Various apron designs were in use at the time, a common style for male workers seems to be cloth with a low bib hanging from the neck on a loop, and tied around the waste.  At Jamestown, the logical material for an apron would be salvaged sailcloth.   Leather aprons are also common for heavy work professions, including lumber workers (which would include potash and charcoal making).

Those involved in heavy or dirty work also typically wore over-pants, basically what slops are all about.  The Diderot encyclopedia from a somewhat later time showed a glassworker wearing old-fashioned (closely resembling slops of our era) over-pants, which are open from the side, perhaps to allow access to pants pockets.  Following that model I made myself a pair of linen-canvas over-pants that are essentially dutch slops open from the side. 

The other logical element for a worker is a brimless hat or cap that stays on no matter what, or, perhaps a cap folded from a cloth.

We might wear some selected detail of clothing accessory from the home country.  For example, fur hats were more common in Eastern Europe but are also documented in use in Western Europe.

Poles and ‘Dutch-men’ in Jamestown

Smith tells us that a group of eight Poles and ‘Dutchmen’ (possibly German speakers, including possibly Pomeranians or Dutch and at least one “Zwitzar” (Swiss)) arrived with the "Second Supply" from London, aboard the ship Mary & Margaret in late September or Oct 1, 1608.  The company recruited these as skilled craftsmen and industry specialists: soap-ash, glass, lumber milling (wainscot, clapboard, and ‘deal’ – planks, especially soft wood planks) and naval stores (pitch, turpentine, and tar). 

Only the identity of the mining/mineral/metal ores specialist is known definitely as a Swiss man named William Volday or Waldi.  It is clear that the glassmaker may have been German, but he was probably a Pole.  The others: naval stores/pitch/tar/turpentine makers was probably a Pole; the millners and lumber specialists were probably 3 Germans, and the potash maker was probably a Pole.  If that were the case, the total would be 4 Dutch-men and 3 Poles for a total of  7… one more is needed for the 8.  One version of the count of Dutch-men sent to build the house is 4, so there could have been an additional deal or clapboard maker who was German, who was not mentioned because he stayed loyal to the colony.  Or that could have been Smith’s error.  The better possibility is that the glassmaker had an assistant, since the glassmen are referred to in the plural on at least one occasion.  Finally, “frankincense” – aromatic plant extract - was mentioned as a product – that may have been another specialist but it could also have been a logical variation of turpentine making.  (See basis for my conclusion here).

An intriguing detailed account of this adventure has surfaced as the 1625 commercial diary of Zbigniew Stefanski, however the authenticity of this work has not been established, and is likely a fraud.  I chose to read it as a well researched and convincing work of fiction, useful for developing a persona.

Another group of Poles arrived in Jamestown in 1619 to manufacture pitch, tar and resins for ships and also to develop the timber industry. The Poles went on strike because they knew themselves to be among the most productive members of the colony, yet, the Legislative Assembly denied them the right to vote. The Assembly granted them full rights in July 21, 1619.

Another interesting aspect is Religion.  The first Poles may or may not have been Protestant (Lutheran) or Catholic or maybe religion was of secondary personal interest to them.  However, a generation later all (up to several dozen) Catholics in Jamestown were exiled, and many of these found their way to the more Catholic-friendly colony of Maryland. It seems reasonable to speculate that some of these exiles were the descendants of Catholic Poles that arrived prior to 1630.  

Polish Glassworking in the 17th C.


First Dutchmen of America

 Primary Sources