Sealing wax

This response addresses the five or so questions posed by Sally
Buchanan regarding sealing wax.

Sealing wax is one of a list of materials including gold foil,
paper, lead, leather, beeswax and various gum-flour recipes that
have been employed to receive the impression of a matrix or other
device intended as a seal. Medieval seals were largely composed of a
beeswax/resin mixture which is often referred to as "true sealing
wax."  The evolution of the material appears to have been guided by
the seal-maker's quest for desirable properties such as greater
security, durability or ostentation. (Reid of Robertland, D., and
Ross, A., The Conservation of Non-Metallic Seals.  Studies in
Conservation, 15, (1970), 51-62.)

In the 16th century, increased trade with the East brought the
introduction of shellac to the formula of what again is often
referred to as "true sealing wax."  The proportions of the wax/resin
mixture for a shellac-based sealing wax are more well documented
that for that of previous formulae.  One such formula that occurs in
a number of sources is "... four ounces of shellac, one ounce of
Venice turpentine and three ounces of vermillion..." to make a red
sealing wax.

In the 18th century, about the time the gum-flour wafer seal was
introduced, other materials were introduced into the wax-resin
sealing wax formula.  This list includes paraffin waxes, tallow and
gutta percha.  In the 1930's a thermoplastic cellulose acetate
compound, trade named "Cellomold" was introduced and used as a seal
material.

More recently (1956), in their publication entitled "Shellac," the
firm of Angelo Brothers Ltd. (shellac producers) of Cossipore,
Calcutta give a recipe for sealing wax: "Shellac...14 parts,
(Venice) Turpentine...12 parts, Rosin... 7 parts, Colour... 2 parts,
Fillers... q.s."  The recipe also includes instructions and
precautions for mixing, molding and even fire polishing the shellac
sticks.  The accompanying text (much like the advertisement that it
is) extols the adhesive quality and working properties of this
particular wax. If you are attempting to make the wax yourself, this
may be the way to go.

One final note, there is an excellent unpublished typescript, "The
Conservation and Technology of Non-Metallic Seals" that was written
by May Cassar at The Department of Archaeological Conservation and
Materials Science, Institute of Archaeology, University of London
(1982).  It is a very thorough study of the technological history
and conservation of a wide range of non-metallic seal materials.

Scott W. Nolley
Conservator
Colonial Williamsburg Foundation

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                  Conservation DistList Instance 12:21
                 Distributed: Thursday, August 27, 1998
                       Message Id: cdl-12-21-004
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