The making of parchment
I shall begin with a
general overview of the process of parchment making. For this purpose using a
recipe from the twelfth century. This can be considered as essentally the basic
process, one that I and others in other lands still use. Variations on this
will be described later.
To begin with we must know the material used in the
preparation: slaked lime (calcium carbonate). Indeed the definition of parchment
is: a skin treated with slaked lime which is dried in a stretched way.
This cooled slaked lime retains the ability to work
into materials for some time. An animal skin immersed for a month in slaked
lime will be considerably digested. This characteristic of lime was first
discovered as far back as the third century ans its use is unchanged from the
middle ages to the present time.
How
parchment was prepared before mediaeval times is uncertain. It is thought that
salt and flour made acid in water was used but there is also the probability
that chicken or dog excrement was used, and who knows what else!
The basic technique
Take
goatskins (1) and stand
them in water for a day and a night. Take them and wash them till the water
runs clear (2). Take an entirely new
bath and place therein old lime (calcem non recentem) and water mixing well
together to for a thick cloudy liquor. Place the skins into this, folding them
on the flesh side. Move them with a pole two or three times each day, leaving
them for eight days (and twice as long in winter) (3).
Next
you must withdraw the skins and unhair them (4). Pour off the contents of the bath and
repeat the process using the same quantities, placing the skins in the lime
liquor, and moving them once each day over eight days as before (5).
Then
take them out and wash them well until the water runs quite clean (6). Place them in another bath
with clean water and leave them for two days (7).
Then
take them out, attach the cords and tie them to the circular frame (8). Dry, then shave them with a
sharp knife, after which, leave for two days out of the sun…(9) moisten with water and rub the flesh side
with powdered pumice (10). After two
days wet it again by sprinkling with a little water and fully clean the flesh
side with pumice so as to make it quite wet again (11). Then tighten up the cords, equalise the tension so that the sheet
will become permanent. Once the sheets are dry, nothing further remains to be
done (12).
Schedula diversarium artium
Theophilus Presbyter. Early twelfth century
Britisch Museum MS. Harley 3915, fol. 128r
So much then concerning the basic process, in the
following article the history of parchment making will be discussed.
Meanwhile here is the manufacture process in diagram
form.
1. 'Take goatskins'
Not only goatskins but calfskins are perfectly suitable. In the
Netherlands the two sorts have always been in use. In Italy and France
sheepskin has been, and still is much in use. How fresher the skin how easier
it is to clean, especially from blood. We notice how difficult it is to remove
coagulated blood when handling a skin from an animal that has not been
slaughtered or bled. The parchmentmaker can, however, make use of this effect,
producing a veined parchment which can be very beautiful. This is not much used
by restorers as the iron in the blood may eventually have an effect on the
skin. The skin from an unborn calf, or one that is born dead, a small lamb or
young goat provides the best material for parchment being supple, soft and yet
quite strong. For this the Germans use the term 'Jungfernpergament'.
Sheep |
Goat |
Calf |
2. 'and stand them in water for a day or a night. Take them and wash them until the water runs clear'
The skins are throughly soaked and swell up. The lime can then penetrate
deeply into the skin. The salt that is rubbed into the skin whilst it is being
flayed is washed out, as well as dirt and blood particles. A poorly treated
skin must first have the fat and any remainig flesh removed. If this is not
done then there will be ugly spots where the blood has soakes into the skin.
Where too much flesh or fat is left on the skin then the lime cannot penetrate
evenly. The intention is that at this stage, the swallon skin must have a
regular open structure across the entire area.
3. 'Take an entirely new bath and place therein old lime (calcem non
recentem) and water mixing well together to form a thick cloudy liquor. Place
the skins into this, folding them on the flesh side. Move them with a pole two
or three times each day, leaving them for eight days(and twice as long in
winter).'
The lime penetrates the skin and at first attacks the soft parts. This
is the fat and the albumen in and around the hair follicles, loosening the
hair. The follicle is the spot in the skin where the hair grows. The lime also
works into the albumen-rich parts which exist between the fibres of the skin.
Soluble chalk deposits are formed. According to other recipes where old lime is
mentioned it is more then likely that this refers to lime already used for
removing hair. Unknown before the middle ages, and for a long time after, this
forms natrium sulphide, a cemical that speeds up the process of unhairing and
having a deeper penetration. The fleshside must be turned outward so that the
lime can penetrate more easily. It is only possible to smeer the wet and
swollen fleshside of the skin with lime. It is folded double with the fleshside
on the inside and laid in a closed vat. The skins will then still remain damp
enough for the hair to be removed without the hair getting into contact with
the lime as happens with a lime bath. This is a particulary good method for
removing clean wool from sheepskin. The recipe specifically mentions 'mixing
well' because the lime must work evenly over the entire skin.
4. 'Next you must withdraw the skins and unhair them.'
The skin is laid on a beam. This is a half round stem that stands at an
angle to the ground. Using a blunt, concave knife the hair can be easely
scraped from the skin which is laid over the wood and moved as necessary. It is
important that as much as possible is removed including the sweat pores, hair
roots, sebaceous glands and surrounding materials. If this is not properly
carried out the skin can quickly deteriorate, or become hard and with too much
fat, cause ugly flecks.
Using a sharp
defleshing knife all the remaining fat and fat membranes (hypodermis) are
removed. Finally the skin is thoroughly rinsed until the water remains clear.
5. 'Pour off the contents of the bath and repeat the process using the same
quantities, placing the skins in the lime liquor, and moving them once each day
over eight days as before.'
The skin, which is now laid with the hair side open, is ready to take
new, fresh and stronger lime. The skill is in preparing the bath so that,
depending on the skin sort and the temperature, as much as possible of the
remaining substances can be freed from the skin, rather than the skin fibres.
The skin is again laid across the beam and scraped clean on both sides.
7. '…and wash them untill the water runs quite clean. Place them in
another bath with clean water and leave them for two days.'
The cleaning process is continued. The skin is "reasonably"
clean because not all the lime must be removed, as the parchment must retain an
even white tint over the entire surface. Also a skin without lime cannot remain
damp for long without the risk of deterioration.
8. 'Then take them out, attach the cords and tie them to the circular
frame.'
The ropes and cords were
tied to the skin and kept streched with stones, balls of parchment, sticks or
with string, today rustfree metal clamps are also used.
Kettle drums are made in
this manner for example. In the middle ages this transparent parchment was
sometimes used for windows. In the countryside in the eastern part of The
Netherlands one can still sometimes see small panes of parchment. The hairside
which is laid against the plastic or metal during the drying out stage is
completely smooth and transparent. This characterisic is very much appreciated
by the drummers when using hands and fingertips.
9. 'Dry, then shave them with a sharp knife, after which, leave for two
days out of the sun…'
The skin is now further
treated to make the skin even cleaner and more supple and to prepare the
parchment for its eventual use. Using a not sharp half moon knife the tensioned
skin is firmly scraped in order to remove the remaining water. The same knife
is used to make the fleshside as clean and smooth as possible. Chalk is rubbed
into the fleshside using a pumice stone. By this means the parchment is kneaded
and evened out. The cords are continually being tightened and the parchment
gradually becomes thinner with an overall increase in the surface area. The
still damp areas are drawn into the chalk as are any still remaining soluble
pieces in the skin. The chalk helps to make the
colour even.
After a few days the chalk and other debris can be removed from the
surface using the half moon knife. Finally the half moon knife, sharpened and
then given a burr on one side, is used as a scraper to remove a thin horny
layer from the surface of the hair side. When this is carried out both sides
have the same characteristics and with the parchment being thinner can be used
for restoration purposes, a quality also much in demand with calligraphers.
10. '…moisten with water and rub the flesh side with powdered pumice.'
Indeed it is the flesh side that requires so much attention. This side
must be continually scraped until an open, velvet like structure is obtained.
11. 'After two days wet it again by sprinkling with a little water and fully clean the flesh side with pumice so as to make it quite wet again.'
I have experienced this aspect of being very important indeed. By making the flesh side slightly damp over small areas at a time, only the remaining fibres absorb the moisture. These then come loose from the underlayer which remains dry. There is a difference in tension so that the wet fibres are easy removable with pumice and chalk. The flesh side now gains its velvety surface.To make the surface smooth again it is only necessary to wipe it with a damp cloth, making the fibres lie flat.
12. 'Then tighten up the cords, equalise the tension so that the sheet
will become permanent. Once the sheets are dry, nothing further remains to be
done.'
Finally the half moon knife,
sharpened and then given a burr on one side, is used as a scraper to remove a
thin horny layer from the surface of the hairside. When this is carried out
both sides have the same characteristics and with the parchment being thinner can
be used for restoration purposes, a quality also much in demand with
calligraphers.