Light Industry in Support of the Jamestown Glassworks: Potash, Charcoal and Lime
April 5, 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.
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
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.
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
Potash (in 17th C. context of a glass
additive, just “salts”)
Potash may be differentiated from Soap-ash
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
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” http://journeytoforever.org/biodiesel_ashlye.html.
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
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
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.
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
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.
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:
Up-and-down sawmill, Sketch-Book of
Wilars de Honcote
illustrated in Kunstliche Abrisz allerhand
Wasser- Wind- Rosz- und Handt Muhlen and Zonca,
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//etext.lib.virginia.edu/users/deetz/Plymouth/framing.html 17t C frame building construction.
http//www.greenwoodworking.com/riving/riving.htm 17th C furniture making and
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.
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.
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
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.
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
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.
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
(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.
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