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Articles by Chris A.
Paschke, CPF GCF CMG
"Preservation Mounting of Vellum and Parchment"
June 1992
The
use of animal skins or "vellum" as a writing surface for the
recording of history and acknowledging accomplishments has long been an
accepted practice, and skins have survived from as early as Egypt 2500BC. Calf, goat and sheep were normally used, but
skins of gazelle, antelope, stag and even ostriches have also been located and
preserved. Vellum is the proper name
given to any high quality animal skin--excluding sheep or lamb--prepared
specifically for the arts of writing, bookbinding and printing (photo-intro).
photo-intro
A
1852 ledger page of sheepskin parchment.
Parchment
is more sensitive to moisture, heat and pressure than vellum.
This
page curled after exposure to 180F and too much pressure.
Vellums
are available in a range of sizes and qualities (photo 1) including
"Grained" premium quality, "Classic" used mostly for
historically framed declarations and heraldry and "Manuscript"
thinner version of Classic, all developed from calfskins. Goatskins such as "grained goat"
and "yellow or white goat" have much more open grain textures than
calf, are rougher, less expensive and often used in bookbinding. Uterine vellum—from an unborn calf--is the
thinnest and highest quality vellum available.
It is extremely smooth, comes from the belly of still-born calves and
although rarely made and quite expensive, may be special ordered.
photo
1
From
L to R: Manuscript calf (medium weight); Manuscript slunk calf (book weight);
Classic
writing calf; Manuscript calf (#3 medium weight); White goat; and Parchment
(sheepskin).
Note
the variation in texture, grain, color , veining and shading.
In
layman's terminology, all writing skins are generally referred to as
"parchment" though the only true parchment comes from sheep. There are also degrees of quality available
when it comes to sheep or lambskins, including "Roman vellum" (a
shinier, absorbent version made as an imitation of vellum, named for its use in
the Vatican); parchment (hard, smooth surfaced, white and oily, the finish
resembles that of an eggshell) and Forel (inferior quality skin produced in
white and tints). The quality of Forel
compares to parchment as goat vellum compares to calf vellum.
PREPARATION
The
distinct difference between "vellum" and "parchment"
preparation directly effects the basic characteristics and reactions of each type
of skin. In order for today's framer to
be able to deal with the assorted documents, maps, certificates and ledger
sheets that may cross his framing table, a basic understanding of skins really
helps. It is important to note that most often you will be dealing with
sheepskin parchment, for vellum is most dominantly used in book leaves and
royal declarations.
Vellum
skins are soaked in lime to remove the hair, scraped, washed, stretched and
room dried. Parchment--sheepskins only--must
be split, limed and scraped 2-3 times to remove the additional fat from the
skins prior to degreasing. Then they are
shaved, whitened and dried unstretched in a hot drying room to remove further
fat, then washed and cleaned for final use.
Visually, vellums are often naturally creamy in color and often
illustrate the veining of the animal, while parchment is much whiter and has a
smoother surface texture.
REFLATTENING
WITH WATER AND PRESSURE
Skins
may be redampened to relax them in an attempt to reflatten prior to framing. Tests must be done on the document prior to
dampening to determine the permanence of the inks and pigments used. With a dampened Q-tip, touch each individual
color lightly to check for bleeding or lifting of color. A 50/50 solution of alcohol and distilled
water should be used during this process, and dampening is generally done from
the back of the document with a cotton ball or squeezed sponge. Another version is transferring moisture into
the skin by moistening a blotter and then placing it in contact with the back
of the skin.
Since
vellums are originally dried on frames much like stretcher bars, when dampened
they will cockle and warp, and attempt to revert to the original shape of the
animal as they dry (if left to dry under no restraints). So to reflatten vellum, it must be dampened
and dried under tension or pressure (photo 2).
If the skin is to be matted, 2" felt lined Bulldog clips may be
positioned around the edges of the dampened vellum while pinning it with
stainless steel pins to a stretching board (as is used with needlework). Vellum is really quite forgiving in it's tolerance for water.
If any of the originally painted pigments have turned powdery or loose, they may be painted over with a thin solution of
soluble nylon in I.M.S. (industrial methylated spirit)...and never dampen gold.
photo
2
This
classic sample was soaked in water and allowed to air dry, causing the lower
right corner to cockle.
The
left corner was pressed flat at 160F in a mechanical press for 5 minutes.
The
top was mounted to a 4-ply board with ArchivalMount tissue at 180F for 2
minutes.
Heavily
dampening parchment will both effect the surface finish and shrink the skin,
about 5% overall (photo 3). To lessen
these dramatic effects, use the lightly dampened blotter method by pressing it
to the skin for just a few seconds. Then
press the parchment between clean, dry blotters under even weight like that of
a closed (not locked) cold mechanical press.
Too much pressure may also cause later curling when dry. Change the blotters every 1/2 hour until
completely dry. Do not leave damp
blotters in contact for extended periods to the skin as it promotes mold
growth. Most skins will water stain
(some worse than others) so spot dampening should always be avoided and
parchment will definitely want to curl (photo 4). Remember, parchment is much more delicate and
reacts much more violently when mishandled.
Predictability is the key, always know what will happen prior to doing
anything. Many applications (moisture
and heat) individually are quite safe, but when applied in collaboration can be
deadly to that "one-of-a-kind" sheepskin ledger page from 1852 (photo
5).
photo
3
Left
sample has been dampened and air dried causing shrinkage.
Right
sample illustrates the unfortunate combination of moisture AND heat
application.
photo
4
First
four (L to R) are calf vellum, with a little cockling and water staining.
The
fifth is sheepskin parchment (curled).
Unlike
parchment, vellum will often flatten under heat.
photo
5
Tested
samples reacted when heat and moisture were applied.
Left
was heat and pressure; center was dampened and air dried prior to heat.
Right
is a more drastic version of heat, moisture and pressure.
MOUNTING
Since
vellum and parchment are naturally prone to buckling, often clients prefer to
have them mounted permanently flat! In
actuality, documents, certificates and diplomas should be treated in the same
manner as a fine art original. Museum mounting
using all the standard conservation methods of hinging with wheat starch and Japanese
hinges on only acid-free 4-ply boards should always be stressed. Slight buckling of a skin with natural
temperature and humidity changes truly is the nature of the beast. It is the one element exclusive to this fine
art original and I personally am an advocate of maintaining that natural
beauty. Other options for mounting skins
include: stretching over coated bars or acid-free museum board and affixing to
the back; wet mounting with adhesives specified for skins; and dry
mounting. Additional heat applications
involve Lamin-all (a heat setting wet glue) and Parchweld. Both of these last two methods involves a
combination of taping, heat and pressure.
Even when vellum is stretched like canvas it will cockle as time passes
and the natural effects of the above mentioned temperature and humidity tightens
and relaxes it. Of course the ideal
environment is 60-70F with 50% relative humidity, a basic thermostatically
controlled museum environment.
When
a dogmatic client pursues the more static and flat look, dry mounting fully
dried skins with low temperature, removable, acid-free tissues is quite simple
and effectively successful. Acceptable
dry mount tissues include ArchivalMount, TM-4 and Drychival.
HEAT
APPLICATIONS
Vellum
will notoriously tolerate much greater temperature and moisture abuse than
parchment. Applying heat alone to skins
will not radically effect them as long as it is not too hot. Tests show that temperatures of 180F for up
to 5 minutes will not do damage to either vellum or parchment samples, although
a tendency toward brittleness does begin to occur.
High
temperatures of over 200F will be asking for trouble, for parchment could
easily be fried. Care should always be
taken when applying heat of any kind, though 160F for 3 minutes to set any low
temperature tissue is very safe (photo 3, sheepskin onto ArchivalMount).
A
combination of heat and pressure while damp will slightly shrink vellum (almost
undetectably), while it will do major damage to parchment (photo 6). Make certain any skin having been dampened to
flatten is totally dry prior to mounting to avoid any irreversible damage. Use your common sense, vellum and parchment
are both natural animal skins and will readily react to other natural elements
safely, when adding extremes of heat (an unnatural element) the other elements
need to be totally under control.
photo
6
Classic
calf (L) and tortured sheepskin (R) after water, heat, and pressure.
Both
stretched and mounted versions of presentation are unnatural to vellum and
parchment, for once again it assumes an inconsistent character from the true
natural look. If archivally hinged,
skins should be placed 1/8" from the glazing for room to breathe, which
can easily be achieved by using multiple acid-free window mats (this pressure
against the edges of the vellum will also minimize overall buckling. Once framed these pieces of fine art must be
hung in a dry (but not too hot) location, preferably out of direct sunlight. Taken well care of, these archivally
preserved masterpieces will last many future generations.
If
dealing with a seriously curled document feels beyond your scope of confidence,
contacting a qualified conservator for assistance or as a subcontract for this
project is always a very viable option.
Other than that, hinging the (original once safely reflattened) and
allowing it to move freely is truly after all…the nature of the beast.
END
For additional articles
on preservation treatment, design or mounting search your desired topic under Articles by
Subject.
If you already know the specific title then search under Articles by
Title.
Additional
information on shipping boxes is found in my book
Creative
Mounting, Wrapping, And Laminating, 2000.
The two most
recent mounting books are
The Mounting
and Laminating Handbook, Second Edition, 2002, and
The Mounting
And Laminating Handbook, Third Edition, 2008.
All books
are available from Designs Ink Publishing through this website.
Chris A
Paschke, CPF GCF
Designs Ink
Designs Ink
Publishing
785 Tucker
Road, Suite G-183
Tehachapi,
CA 93561
661.821.2188
info@designsinkart.com