Cyclododecane

In the last few weeks there were some remarks or questions
concerning the use of cyclododecane. Cyclododecane is one of the so
called volatile binding media, which can be used for temporarily
sealing or consolidating fragile objects. We developed these new
materials resp. this new method in cooperation with Hans Hangleiter,
restorer for wallpaintings. Our method was published in 1995, in the
meantime there are some more publications and diploma theses (see
list below). As I am not quite sure how far German publications are
known in English speaking countries I want to give some general
information about the volatile binders and their applicability.

The so called volatile binders are non-polar organic compounds
belonging to the class of saturated cyclic hydrocarbons. They are
waxy solids at room temperature with a remarkable vapour pressure so
that they are able to evaporate in an appropriate time. The volatile
binders can be used as hydrophobic protective coatings for
water-sensitive objects, as consolidants for fragile objects during
excavation, transport or handling, as sealant for objects or
surfaces in various working processes. We started to investigate the
applicability of the materials within the field of conservation of
wallpaintings or stone objects. In the meantime we have tested the
substances in numerous laboratory experiments and in practical
applications with various kinds of objects consisting of organic in
inorganic materials: paintings and sculptures, paper, textile and
wooden objects as well as stained glass, metal objects or composite
materials.

The demand on substances used as volatile binding media ca be
summarized as follows: they must be solids at room temperature. They
must have a sufficiently high vapour pressure and evaporate free of
residue within an appropriate time. They must be non-toxic and
environmentally compatible.These criteria are fulfilled by a series
of non-polar cyclic hydrocarbons such as Cyclododecane, Camphene,
Tricyclene and--with some restrictions--Menthol. At room temperature
they are solids with a waxy, smooth and slightly tacky consistence
and they evaporate under atmospheric pressure. The evaporation rate
depends on the molecular structure of the compounds: Cyclododecane
and Menthol  evaporate quite slowly (0.04mm/24h), whereas Camphene
and Tricyclene have a higher vapour pressure and vaporise quickly
within a few hours (0.4mm/24h). A fundamental precondition for the
application of these materials is their complete and absolutely
residue-free evaporation. A complete evaporation is guaranteed only
when the materials are free from impurities. For this reason only
products of high purity have to be used. Whereas Cyclododecane and
Tricyclene are chemically stable, Camphene must only be used with a
stabilising additive, for it might be sensitive to oxidation. (List
of suppliers below)

As non-polar compounds the volatile bindings media are easily
soluble in non-polar solvents such as hydrocarbons, halogenated
hydrocarbons, ether and esters. They are mostly insoluble in
alcohols and acetone. They are not miscible with water. Menthol has
a more polar structure, it is readily soluble in alcohols and other
polar solvents, as a consequence it is only slightly hydrophobic.
According to their physical properties the volatile media can be
used for different purposes: Cyclododecane with the rather slow
evaporation is suitable for long term consolidations or sealing (the
coatings last for several weeks depending on their thickness).
Camphene or Tricyclene can be used for short time applications. The
three compounds are non-polar and hydrophobic they are very suitable
as water-repellents, but they are only poor adhesives. Compared to
the others the more polar,  non-hydrophobic  Menthol has a stronger
adhesion, it is mainly used as temporary adhesive or coating. Like
waxes the volatile binding media can be applied as a melt (the
melting points are about 40-65 deg. C) or as a solution in non polar
organic solvents (preferably in petroleum benzine boiling point
30-40 deg. C or petroleum benzine b.p.100-40 deg. C). The solid
layers formed ether by solidification of the melt or by evaporation
of the solvents have different properties. They can be dense and
impermeable (solidified melt) or crystalline, with fine or coarse
crystals, when they derived from from solutions. You should use a
melt or a solution in low boiling solvents when you need a dense
hydrophobic surface (e.g. to protect water sensitive parts of an
object during a cleaning process). When you need a structural
consolidation (e.g. for stabilising fragile objects during transport
or excavation) you should use a solution in high boiling solvents
preferably spread on a warmed up surface. The evaporation of the
volatile binding media does not only depend on the chemical nature
of the compounds (see above) but also on the structure of the
impregnated system. Evaporation from  porous materials such as
stone, mortar or wood needs more time than from non porous or
thin-layered materials. You have to be sure that all the binding
media has vaporised completely before you add "normal" consolidants
or coatings. It is possible to accelerate the evaporation rate by
ventilation or warming, on the other you can retard the evaporation
by covering the objects with foils of plastics etc.

Examples for the application of volatile binding media: Temporary
consolidation of fragments of roman wall paintings or of a gothic
polychromed sculpture during excavation, mounting, cleaning and
conservation

Fixing of loose paint layers on stained glass in the case of a
mechanical cleaning  Protection of water-sensitive parts of objects
(textile, paper, parchment etc) during a cleaning process with water
Protection of surfaces (wallpaintings, wooden objects) during the
impregnation with consolidants to prevent a discoloration or
alteration Temporary consolidation of fragile  objects (stone,
mortar etc) for sampling or  for the preparation of samples for
examinations Temporary sealing of surfaces as a partition layer for
moulds.

The introduction of the volatile binding media as new materials for
conservation and restoration purposes offers a lot of interesting
and promising possibilities for the treatment of fragile and
sensitive objects. Up to now extensive research work has been
carried out on the materials, numerous objects have been treated
successfully this new method. And there is still a lot new ideas for
further applications.

We are looking forward for your remarks, questions or suggestions.

Suppliers for the volatile binding media are:

    Dr. Georg Kremer Farbmuhle
    D-88317 Aichstellen

    AP Fitzpartick Fine Art Materials
    142 Cambridge Heath Road, GB London E1 5QJ

    Kremer Pigmente Inc.
    Elizabeth Street 228
    New York, NY 10012

    Deffner und Johann,
    Muhlaecerkstr. 13
    D-97520 Rothlein.

List of publications

    Hangleiter, H., Jaegers, E., Jaegers, E., Fluchtige Bindemittel.
    Zeitschrift fur Kunsttechnologie und Konservierung 9, 385 (1995)

    Hangleiter, H., Erfahrungen mit fluchtigen Bindemitteln, Teil 1.
    Restauro, 104, 314 (1998)

    Hangleiter, H., Erfahrungen mit fluchtigen Bindemitteln, Teil 2.
    Restauro 104, 468 (1998)

    Hiby, G., Das fluchtige Bindemittel Cyclododekan. Restauro, 102,
    96 (1997)

    Riedl,N., Hilbert, G., Cyclododekan im Putzgefuge. Restauro 104,
    494 (1998)

Elisabeth Jaegers
Erhard Jaegers
Naturwissenschaftliche Beratung bei der Erhaltung von Kunst und
Kulturgut - Mikroanalytisches Labor
Hemberger Str. 75
D-53332 Bornheim

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                  Conservation DistList Instance 12:67
               Distributed: Wednesday, February 17, 1999
                       Message Id: cdl-12-67-001
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