Parylenbeschichtungen – Möglichkeiten für die Restaurierung und Konservierung als Schutz vor anthropogenen Umweltschäden.
Jonas Jückstock
(in cooperation with Fraunhofer IGB – sponsored by Deutsche Bundesstiftung Umwelt)
Materials of the last 150 years, like polymers as well as picture- and sound carriers, who are decomposing or whose sensitive layers suffer mechanical damage, are endangered by direct harm due to the rapid technological development since the beginning of the industrial age to the digital age. Airy pollutants like ozone, nitrous gases and sulphur oxides but as well aggressive dust, harmful UV-radiation, fluctuations in temperature and relative humidity jeopardize such objects acutely. Profound damages on pieces of art are the consequence. Keeping those fundamental problems in mind, the work examines parylene coatings methodologically and materially. Id est countering by securing matter in a restoring meaning as well as preserving and conserving such from further environmental damages. The work investigates if and how parylene coatings are capable to protect art from those harmful factors and how to preserve them. Further it will be examined how parylene coatings work for consolidation.
Parylene coatings are polymer coatings which are applied at room temperature under low vacuum. Starting products are granules of the polymer [2.2]Paracylcophan. This polymer is introduced in a machine, that was designed for this particular process, it is vaporized and pyrolized. Radical monomers are formed by thermal cleavage and as soon as they cool down to room temperature they are polymerized to a linear ultrathin polymer film. Skipping the liquid phase during condensation a firm film is formed.
Parylene is not harmful for its user and proves to be inert, meaning it does not react with the coated surfaces. A thermal or chemical prior- or post-treatment is not necessary. By using the vapor deposition a conformal layer is applied without contact or the use of solvents. Thus the thickness of the layer is conformal too, particularly objects that are sensitive to solvents can be conserved and consolidated.
Own preliminary studies on that topic showed that parylene coatings have the potential to solve some very tricky problems occurring in conservation and restoration. Apart from examining varieties of parylene polymers and their short and longtime behavior for conservation use, the field of modern materials as polymers or for instance photographic negatives will be in the focus of research. In example as parylenes are applied in low vacuum it has to be examined if this supports the migration of plasticizers to the surface or leeching in general. Furthermore it shall be studied whether softeners influence the abilities of the parylene coatings.
Especially in fields which exclude preventive measures to conserve or in fields where such solutions are not financeable, parylene coatings pose a fortunate and sustainable solution to protect the artefacts. The needed high professional expertise is justified by the exceptional results of the method, whose are currently a unique characteristic in conservation in Europe.
selection of additional references:
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– Carter, Henry A.: The Chemistry of Paper Preservation Part 3. Strengthening of Paper, in: Journal of Chemical Education, Vol. 73, No. 12, 1996, S. 1160- 1162.
– Grattan, D.W., Bilz, M.: The thermal aging of parylene and the effect of antioxidant, in: Studies in Conservation, Vol. 36 No. 1, 1991, S44-52.
– Grattan, David: Parylene at the Canadian Conservation Institute, in: Canadian Chemical News, Vol 41, No. 9, 1989, S. 25-26
– Halvorson, Bonnie G.: Effect of light on the properties of silk fabrics coated with Parylene-C, in: Studies in Conservation, Vol. 39 No. 1, 1994, S45-56.
– Humphrey, Bruce, J.: Paper Strengthening with Gas-Phase Parylene Polymers: Practical Considerations, in: Restaurator 11, 1990, S. 48- 68.
– Humphrey, Bruce, J.: The Application of Parylene Conformal Coating Technology to Archival And Artifact Conservation, in: Studies in Conservation, Vol. 29, No. 3, 1984, S. 117- 123.
– Jückstock, J: Interdisziplinäre Seminararbeit TUM 2011
– Jückstock, J: Parylene – eine Alternative in der Konservierung und Restaurierung,
Diplomarbeit der Technischen Universität München, 2012
– Mertz, Klaus: Vakuum mit Vorteilen, in: Magazin für Oberflächentechnik,. Bd. 57, Ausgabe 7/8, 2003, S. 35- 38
– Nosal, A. et al.: Parylene coating on biological specimens, in: Journal of Achievments in Materials and Manufacturing Engineering, Vol. 37, Issue 2, 2009, S. 442- 447.