The Early History of Hemp Processing

By: Susan Koziel (SCA: Kataryna Tkach) , Feb 25, 2011

The History of Hemp

Hemp has been cultivated by humans for about 10,000 years (Mukherjee et al. 2008). It was likely independently domesticated in multiple centers (Figure 1) the two major areas being Northern Eurasia (fibre cultivars) and the Indian subcontinent (medicinal cultivars) and had four major uses: oil, fibre, medicine, and food (Sneader 2005), (Russo et al. 2008), (Mukherjee et al. 2008). The different uses of hemp led to different varieties being developed very early, and by the 1500’s the low THC fibre cultivars used in eastern and western Europe were considered to be a separate plant (Cannabis sativa) from the high THC varieties grown in Southeast Asia and Africa (Cannabis indica). Recent genetic testing has shown that these two types are in reality subspecies of the same plant (Cannabis sativa). The only other species in the same genetic family is hops, which has been shown to occasionally have crossed with hemp early in its genetic history (Mukherjee et al. 2008).

Figure 1: Modified from: Clarke, R. (1999). Botany of the genus cannabis. In P. Ranalli (Ed.), Advances in Hemp Research (pp. 1-19)

The introduction of hemp into Western Europe can be determined using radio carbon dating of pollen grains, and seems to have come in a two pronged manner (Flemming and Clarke, 1998). First it was established in the Balkan states and in Italy during the Greek and Roman Empire, from which it spread north and west through eastern and southern Europe. When the Norse established trade with the Mediterranean, hemp cultivation spread to Scandinavia and then through northwest Europe.

Greek (Herodotus, 5^th century BC) and Roman (Pliny the Elder, 23-79AD) literature mentions the various uses of hemp (fibre, oil, medicine, and food). Pliny also notes that cloth made from hemp cannot be distinguished from that made from flax, something that has been true until 10 years ago; when reliable technologies were developed. Standard microscopic examination does not give a definitive answer between linen made from flax to that made from hemp, so electron microscopy or other destructive methods were the only way to determine the material definitively (Good, 2001). In the last two to five years non-destructive methods to distinguish between the various types of bast fibres were still being developed; and include the use of such things as synchrotrons, FTIR, and NMR (Current research, AITF and other institutes, 2011).

Prior to recent times museums tended to assume one of two things. They based the fibre type on current cultivations in the area of the find; usually flax in Western Europe, and hemp in China or Eastern Europe. Alternately, they labelled items as being linen. Linen is defined as any plant fibre, not just flax. However, pollen studies and subsequent studies using the most up to date techniques have indicated that some items thought to be one type of bast fibre were in fact a different one (Good, 2001).

Large scale hemp cultivation reached England last about 500AD and was thought to have been brought there by the Anglo-Saxons and was continuously cultivated until the 14^th century when a drying period saw a drop in the amount of hemp (Flemming and Clarke, 1998). Earlier finds of bast, string and fabric in Scotland, place the cultivation of hemp in the bronze age. (Ryder, 1993). Hemp cultivation in England peaked again in the early 16^th century when Henry VIII passed a law in 1533 requiring farmers to grow hemp for rope, sail cloth, net and fabric. This was repeated by Elizabeth I in 1563 and repealed in 1593 (Robinson, 1995)

Processing Hemp

Information on the specific way to process hemp and other bast fibres is very sketchy. There are artifacts such as combs from medieval Russia (Figure 2) and drawings of the process, the most complete being a mural cycle showing the processing of some type of bast at the Kanonikerhaus in Constance, Germany, c. 1320 (Figure 3).

http://visualrian.ru/en/site/gallery/#730507/context[flow][category]=art

Figure 2: Flax Combs from medieval Russia, Moscow history museum

http://www.bildindex.de/bilder/zi1800_0105a.jpg

Figure 3: Mural of bast processing Kanonikerhaus in Constance, Germany, c. 1320

Editors tend to note that this means using female for spinning fibre and the male for cordage (Grearey, 2005 ). However, in reality the male plant has a very thin stalk, relative to the female, produces lots of pollen and dies much earlier than the female plant. If the males, which die earlier, were collected they would produce a very fine fibre when processed. Modern agriculture only processes the female plants which develop large seed heads

For July husbandry, Tussar than goes on to say:

Wife pluck fro thy seed hemp the fimble hemp clean

This looketh more yellow the other more green

Use t’ one for thy spinning leave Michael the other

For shoe thread and halter for rope and such other

Here he is clearly talking about the male hemp which produces the seed (pollen), hence seed hemp, which fertilizes the plant which then gives seeds for next year’s crop. He is stating that the remainder of the female plants be left until after Michaelmas (left for Michael).

In the section on September Husbandry he discusses what to do after Michaelmas (Sept 29):

Now pluck up thy hemp, and go beat out the seed,

And afterward water it, as ye see need;

But not in the river, where cattle should drink,

For poisoning them, and the people with stink.

Hemp huswifely used looks clearly and bright

And selleth itself by the colour so white

Some useth to water it some do it not

Be skilful in doing for fear it do rot

This clearly indicates the two ways to ret hemp once it’s been pulled, not cut down, and the seed beaten off the stalks. Most of his detail describes Pond retting, a more common manner of retting in England, stating that pond and water retting can poison water ways, and may smell bad if allowed to over ret. He seems to mention dew retting as an afterthought in the line (some useth to water and some do it not).

His section on different Houswifery chores mentions:

Let some to peel hemp or else rushes to twine

To spin or to card or to seething of brine

This is interesting as it describes peeling rather than breaking hemp as a way to remove fibre from the stalks.

A more complete discussion of the processing is found in a document published just post period, in 1615, by Gervase Markham (1568-1637). It describes the processing of the dry flax or hemp more completely stating that the hemp stalks can either be dew retted, left in the field for 2-5 days, or water retted in either a pond or running water for 2 to 5 days before it is taken out and dried. Markham does not discuss another form of dew retting commonly practiced in colder locations, specifically Russia and the Scandinavian countries. This is now called snow retting. When the growing season is short, the hemp is often not ready to be pulled until after the first snow fall, in which case it was pulled and left on the snow to rett over the winter, and taken up before the ground melts in the spring and dried. (Encyclopaedia Britannica, 1856). This produces a finer fibre then water or pond retting. Russia was well known for its fine quality hemp and the Muscovy Company (1555-1649) exported Hemp regularly to England during this period (Gorokhovsky, 2004).

Once dry the hemp is beaten with “ripple combs”. Ripple combs are course wide toothed iron combs used to remove the leaves and the seeds from the stalks. The stalks are then stored in a dry location until they can be processed further.

The hemp is then broken in one of three ways. First is to use a flax break. Markham goes into a fair amount of detail about the different types of breaks stating that for hemp one should use a break that is open and has a “wide tooth” rather than using the narrow sharper break that works for flax. He does not mention the second or third methods which are to use a hammer or mallet against a stone (Pliny, volume 9, 23-79), or to peel it (Tussar, 1580). A figure said to be peeling flax is seen in the Kanonikerhaus mural (1320, Germany, Figure 4). However, I suspect it is hemp for two reasons, the sizes of the stalks are much larger then flax stalks and flax cannot be peeled by hand.

Figure 4: Enlargement of first figure in the Mural of bast processing Kanonikerhaus in Constance, Germany, c. 1320

Once broken, the hemp is swingled, or scutched against a board, swingle-tree-block, with a scutching knife, or a swingle-tree-dagger, to remove the sheave, also called core or hurd (Markham, 1615). Alternately the sheave can be removed from hemp, but not flax, by using a wide tooth comb or iron scrapper. At this point Markham states that the fibre can be sold.

Before it is ready to spin however, one must swingle it again and then heckle, or hackle, it. A heckle is a board with nails, which the fibre is pulled through. Initially the nails are spaced widely. Post period sources suggest using a heckle containing 12 nails per square inch to start, then increasing the density of nails to 16-20, finally 80-100, used only for very fine material (Figure 3) (Atton, 1988). Markham seems to indicate that this might be done wet, as he talks about allowing the hemp to dry once it has been heckled the first time through and heckling a second time – yet doesn’t discuss wetting it initially. He also discusses using the tow, the stubble that comes off during the heckling, to spin hemp cloth that is as fine as flax.

Once that is done the hemp must be spun. Hemp must be spun wet so that the fibres bond to each other. There are three possible methods from which to choose. First plain water can be used. While this works it is not ideal to bond the fibres and form the very strong thread that is characteristic of hemp. Alternately saliva is used, as described in the folk tale of the three spinners (collected by Giambattista Basile 1566-1632). One had a swollen thumb from drawing the thread, one had a swollen lip from wetting the thread and one had a swollen foot from treading the wheel. This is thought to have been a description of women who processed flax.The fibre was allowed to pass along the lower lip as it was being drop spun which caused small cuts which would swell because they became infected from the improperly cleaned fibre (the retting process giving the fibre a higher bacterial load). The same factors caused the swollen thumb. The swollen foot is theorized to be from sitting so much. This also suggests that saliva was the liquid of choice in the middle ages for spinning plant fibres. The enzymes in saliva dissolve some of the cell wall and allow flax, hemp, and nettle fibres to stick to each other. The last solution that can be used is to boil some of the tow, and hurd along with some of the seed or oil from the plant in question and then strain the liquid out. This liquid can be used instead of saliva to make the fibre sticky since the liquid contains bits of the glue that holds the cell wall together naturally.

What I Did To Try And Mimic The Historical Information

This project was accomplished in multiple steps. The initial growing of the hemp was done for a research program at Alberta Innovates Technology Futures, in which we hand- sowed a plot with 100,000 seeds, of which 30,000 were expected to survive. Over the course of the summer they were looked after and then they were hand harvested. During the same summer other larger plots in different areas of Alberta, Manitoba, and Ontario were also grown and harvested as part of a varietal trial, for which we do not use retted hemp.

However, by the next spring I was able to use some extra hemp from the varietal trials that had been left over the winter and had snow retted. I chose to process one of the oldest varieties that we were testing, a low THC variety called Silesia. It is a Polish cultivar, which produces lots of strong fine fibres, and was developed from the landraces grown in the province of Silesia in the 1960’s. Its close generation to the landrace and its polymorphic nature (different sizes and shapes) suggest that it is still very like a landrace (a historic cultivar), but I have not seen the specific breeding records so cannot be certain.

The different types of retting produce different quality and colour to the fibres (Figure 5, and 6)

Retting is the process of allowing microbes, or in the modern day chemicals, to break the fibres away from the stalk of the plant. There are a number of ways that one can ret fibre plants. Pond, stream, dew, and snow retting are the non-modern, non-chemical, methods used most often.

In pond retting the plants are cut and sunk into a shallow pool of water until they are soft and the fibre comes away from the core easily. It takes from a couple of days to a couple of weeks, depending on the water temperature and the type of microbes in the pond. Often the fibre produced is not as desirable because the retting is not uniform. Usually some fibre is over retted and some under retted. Pond retting also tends to produce a grey coloured fibre.

Stream retting is sinking the plants in flowing water for several days to weeks which produces a more uniformly retted yellow grey fibre of average quality.

Dew retting is letting the cut fibre to lay in the fields allowing the dew to collect on it. This is cautioned against in the historical documents from England because the moisture levels are so high that it produces poorer quality fibre than water retting, however it seems to have been used on the continent regularly. It also cannot be adequately done in a dry climate or too close to the onset of winter so in Central Alberta, where I live, it is very rare to get conditions where this is possible to attempt. Dew retting produces the highest quality fibres according to the current AITF fibre trials.

For hemp, one more process exists, that of snow retting. For this, plants are cut down and collected so that they do not start retting. Once the snow falls and covers the ground, hemp stalks are placed out on a tarp or a wooden board, and then the snow is allowed to cover the hemp for the winter. The hemp is allowed to thaw in the spring but not allowed to contact the ground or it will start dew retting. Snow retted hemp produces very fine bright golden or white fibre.

Once the fibre bundles are retted they need to be dressed, that is to break, scutch, and heckle the fibre. A flax break looks like the following schematic (Figure 8) is typically wooden, and works somewhat like a large dull wooden paper cutter. I have no pictures of the one that was made and then destroyed trying to process hemp stalks.

As I mentioned the break tried on the snow retted hemp broke. The pin connecting the top of the break to the bottom split because of the heaviness of the Hemp stalks. I placed too many stalks between the parts and pushed down too heavily. Eventually the arm was taken off the break and slid under another grooved piece of wood clamped to a metal table and tried again. This was a Kludge but it worked for the few days while the fibre was processed. For the very large hemp stalks we found it easier to place the stalks between a couple canvas drop cloths and dance or jump on them.

The scale of difference between fibre hemp and flax is very apparent in Figure 9.

Based on the size of the plants, the type of break used for bundles of flax will not last as long when processing hemp.

Figure 9: Scale of Flax to Hemp.

Figure 10: Broken fibre ready to be scutched.

Hemp fibre can also be hand stripped if necessary by holding the fibre so it slides between your first two fingers as you hold the stalk in the palm of your hand which produces an angle that allows you to strip the length easily and quickly. This gives an advantage of not having to scutch the fibre, though you still must heckle it.

Scutching is the process of removing the hurd remaining in the fibre after it has been broken. This is done with a wooden scutching knife (Figure 11). To scutch fibres you hang them and then scrape and beat the knife down the length of the fibre. An iron scraper can also be used, or for hemp something like a metal dog comb. (Figure 12) Scutching produces lots of hurd (woody fibres, also called core, or shive in flax) and some tow (small coarse fibres which grow horizontally rather than vertically in the stem). I save both for making a liquid for spinning the fibre.

Once the fibre is scutched it needs to be hackled it in order to divide the fibres and remove the remaining epidermis. If it is not hackled the spun material will be coarse and the excess bits of epidermis can cut fingers and leave slivers. Hackles (or hatchel or hetchel) are basically beds of nails first 12per square inch, then 24, 48 and finally 80 nails per inch used in turn to process finer and finer fibres. (Atton, 1988).

Figure 13: 12 nails per square inch (Right), and 24 nails per square inch (Left) hackles.

After hackling the fibres through the 50 needles per square inch hackle the fibres were still fairly stiff, and reading through Markham’s information more carefully I decided to try wetting some of the hemp at various stages of heckling to see if it would lose some of its stiffness.

The first attempt with wetting gave shorter fibres that once dried again were stiff (Figure 14). The second trial gave better results if the fibres were dampened, not wet, and then hackled until dry. The fibre remains long and yet opens up better then with the other trials (Figure 15).

Samples of the dry processed fibres, both those that were processed with the finest and second finest hackles, were spun using a drop spindle with saliva as the binder. The ball of flax was spun using fibre I processed during a class on flax processing given by Countess Elisabeth de Rossignol (Figure 16).

Figure 16: Bottom – Drop spun flax; Middle – Hemp processed dry using 12, then 50 pins per square inch; Top – Hemp processed dry using 12, then 50 pins per square inch, then 24 pins per inch.

It is important to note that flax and hemp can be spun coarser and finer and the difference between the two cannot be distinguished using either colour or weight of the fabric woven with the material. The term linen does not specifically imply that the fibre is hemp or flax, and often an archeological find is classed as linen - meaning any bast fibre (hemp, flax, or in some cases nettle) and the type of plant is assumed to be whatever is known to be commonly grown in the area which isn't necessarily the correct assumption to make. The only way to accurately distinguish the difference between the two fibres is to look at them under an electron microscope.

References

Atton, M. Flax culture from flower to fabric. 57, Ontario: The Ginger Press, 1988.

Basile, G. Lo cunto de li cunti overo lo trattenemiento de peccerille. Published posthumously 1637. English translation Batsy Bybell 2000 (http://en.wikipedia.org/wiki/The_Three_Spinners)

Becker, Helmut, “Personal Communications” during International conference on flax & other bast fibres. 2008. (http://www.saskflax.com/documents/presentations/10B_Becker.pdf)

Clarke, R.C. "Botany of the genus Cannabis." In Advances in Hemp Research, edited by P. Ranalli, 1-19. New York: Binghamton, 1999.

Encyclopaedia Britannica, “Hemp”. Encyclopaedia Britannica. Vol. XI, Boston: Little, Brown, and Co., 1856.

Fleming, M.P. and Clarke, R.C. “Physical evidence for the antiquity of Cannabis sativa L.” Journal of the International Hemp Association 5, no.2 (1998): 80-92.

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Gearey, B. R., Hall, A. R., Kenward, H., Bunting, M. J., Lillie, M. C. and Carrott, J. “Recent palaeoenvironmental evidence for the processing of hemp (Cannabis sativa L.) in eastern England during the medieval period.” Medieval Archaeology 49 (2005): 317-22.

Gorokhovsky, A.“Trade and diplomacy: The English merchants in sixteenth century Russia” Student Economic Review 18 (2004):63-73.

Markham , G. The English House-Wife: Containing the Inward and Outward Vertues Which Ought to Be in a Compleat Woman 141-153. London: Printed for George Sawbridge 1675, 1615.

Mukherjee, A., et al. "Results of molecular analysis of an archaeological hemp ( Cannabis sativa L.) DNA sample from North West China." Genet. resour. crop evol. 55, no. 4 (2008): 481-485.

Pliny the Elder, Natural History, volume 9, translated by W.H.S. Jones, Massachusetts: Harvard University Press, 1949. (http://www.masseiana.org/pliny.htm)

Robinson, R. The great book of hemp: the complete guide to the environmental, commercial, and medicinal uses of the world's most extraordinary plant. 121, Rochester, Vermont: Park Street Press, 1996.

Russo, E.B., et al. "Phytochemical and genetic analyses of ancient Cannabis from Central Asia." Journal of experimental botany 59, no. 15 (2008): 4171-82.

Ryder, M.L. “Probable hemp fibre in bronze age Scotland.” Archaeological Textiles Newsletter 17 (1993): 10-13.

Sneader, W. "Legacy Of The Past." In Drug discovery: a history, by W. Sneader, 8-11. Hoboken, N.J.: Wiley, 2005.

Tussar, T. Five Hundred Points of Good Husbandry… edited by W. Mayor, 4, 20, 21, 110, 146, 153, 168, 172, 248, 334 (1812).