“CONSERVATION VERSUS RECONSTRUCTION.”1 DO WE NEED OTHER OR NEW CRITERIA FOR CONSERVING ARCHITECTURAL SURFACES OF THE 20THCENTURY?

Until today, in most European countries there is no juridical definition or legal recognition of the profession of the conservator-restorer. This fact means an almost complete lack of specific regulations anticipating conservation-restoration activities and stipulating the quality of these activities. The absolute need for qualified professionals, for a legal status, for an evaluation of the dynamics in a conservation–restoration project and finally for an analysis of the essential methodological steps of the conservation project require evidence of professional responsibility, competence and qualification. At the very beginning of the conservation of 20th century architecture, the professional figure of the architect wasn ́t discussed in his historically grown leading position. The task of the conservatorrestorer and of the conservation sciences at that time was to take part in a planning process that often started with a “reconstruction concept” for regaining the lost “original” design of the architecture. It seemed to be more important to reconstruct “ideas” than to follow the traces of the authentic materials, and to document and conserve them. Often this was justified with the alleged “special status” of modern architecture which was supposed to be too fragile and too ephemeral to be conserved in the same way as other historical monuments. This article wants to illustrate that effective “project management” based on a shared and transparent theoretical fundament is able to bring about a conciliation of the apparently diametrically opposed opinions and concepts of “Conservation” and “Reconstruction”.


Preamble
The ICOMOS conference in Florence in 2018 titled Conservation Ethics Today: are our Conservation-Restoration Theories and Practice Ready for the 21 st Century? as part of numerous initiatives on the occasion of the European Year of Cultural Heritage (EYCH) 2018 was without doubt of particular intellectual interest for various actors in the audience concerned with the everyday practice of conserving our architectural heritage. Just starting with the conference title, one could ask whether the 21 st century used as a temporal parameter in the posed question was per se appropriate and useful to describe and evaluate our contemporary dilemmas in order to be prepared for the professional tasks of only the coming decennia. Considering the already perceivable impressive consequences of the Third Industrial Revolution for daily life, the consequences for our profession are still less predictable. For sure, the targeted 21 st century describes an uncertain and long future -more than the usual life expectancy -so it should be understood as a metaphor for an unknown task to be coped with using the best means in theory and practice. This metaphor is not absolute and therefore without doubt there will be no proper solution or answer to the question posed here. Instead -as a consequence -the argument proposed in this paper should be based more on experience of the recent past but hopefully avoiding apparently too easy solutions of the reigning zeitgeist. Time isn´t absolute, it is relative and so are our theories and practices as well as the value system of a society and its oscillating prospect of evaluation in time and places. However, relativity doesn`t mean (cultural) relativism that could offer cheap excuses for deficits in our thinking and acting. For that reason, professional standards are to be considered the distilled knowledge of a community of experts. They represent an agreed and reliable way of acting for a certain period of time -until innovations outnumber the existing standards. It is to be considered a slow but variegated and discontinuous process. Conservators-restorers know only one given standard which is a categorical imperative: conserving and maintaining the material existence of artefacts and architecture for future generations. If this conditio sine qua non is omitted, the profession of the conservator-restorer is futile. But who can be defined as conservator-restorer? The craftsman experienced in traditional techniques, the academic conservator-restorer, the art historian, the architect, the civil engineer, etc.? In recent times -for good reason -inter-, multi-and transdisciplinary approaches have also started to prevail in conservation politics. Nowadays, effective heritage conservation institutions assign to each involved professional a certain significant role in a participatory decision-making process, based on internal relationships, shared values, adaptive system and ongoing dialogue. Shared decision-making finally involves not only experts but also the interested public or private stakeholders and brings together diverse opinions and expertise in a holistic approach.
Attempt of an answer to the question in the title Indeed, the above assumed categorical imperative for conservators-restorers could already answer this rhetorical question from a Central European perspective: we don`t need any new criteria for the conservation of architectural surfaces of 20 th century monuments! However, the argument appears to be far more complex than the mere act of doing conservation-restoration: a benevolent and democratic socio-political and cultural-economic environment is a minimum requirement. Shortly before the start of the second decennium both pillars seem to have started to totter. For good reason, right after the reunification of the two formerly divided German states vivid and often controversial theoretical discussions were already centered on the then existing and desirable standards of conservationrestoration and -above all -on the crucial question of reconstructing lost heritage of World War II. After the armed European conflicts of the 1990s and after the traumatic experience of worldwide terrorism intentionally inflicting irreparable damage on artistic and architectural heritage, the debate on virtual or real reconstruction, on copies, replicas and fakes is celebrating a great comeback (See: Hassler & Nerdinger, 2008;Hillmann, 2008;Habich, 2010;Nerdinger, 2010). In order to emphasise the above given statement, it is necessary to briefly summarise the "state of the art of conservationrestoration" in the international discussion, as it has evolved since the European Architectural Heritage Year of 1975(ICOMOS Austria, 2015. As is well known, the motto for the EAHY 1975 was A future for our past and promoted among other didactic ambitions the academic and professional education of conservators-restorers, especially for the working field of architectural conservation-restoration. Auxiliary means were the establishment of appropriate building material archives, the safeguard of conservation-restoration-related findings, and the experimental material-based reproduction of historical production and working methods as art techniques and materials. Finally, conservation sciences gained increasing importance not only as an auxiliary discipline in heritage conservation institutions, but as an important and highly specialised field of research in the conservation-restoration of traditional and modern building materials. Common to all contemporary codes of ethics in conservation is the topic of a "treatment that should be carried out to the minimum extent necessary". María Rubio Redondo asked about the meaning of "what is necessary" and answered: "conservation should provide balanced solutions in response to the necessities of the individual work of art" (Rubio Redondo, 2008). Salvador Mũnoz Viňaz was very conscious of the continuous minimal loss of potential meanings and of the objective fact of inevitable degradation that leads in the end to the total loss of any work of art, when he stated that the concept of "minimal intervention" should be replaced by the concept of "balanced meaning loss" (Mũnoz Viňaz, [2005] 2009). This is decisively aided by the special development of layers that could protect from wear and tear: so-called "buffer", "protection" or "sacrificial" layers, which are compatible with the precepts and demands of the monument's protection. They are thought to have the capacity to protect the original surfaces and may also be applied to a materially identical reconstruction of the same surfaces Danzl, 2008/1;Danzl, 2008/2;. The concepts of minimum intervention or "balanced meaning loss" as the possibly most extensive conservation method of preserving the authenticity of a monument's materiality are the primary objective that surely should be followed without dogma. Even the preservation of invisible layers and materials as part of a newly interpreted structure follows the concept of sustainability: Not everything that is discovered must be revealed. Not everything that is revealed must remain visible. The reconstruction of lost states or design issues in the life of a monument is -still? -not a priority of the heritage conservation. In this perspective, building archaeology, material science together with conservation sciences offer the essential contributions to the practical conservation of the monument as well as to the inventory. It is important to underline that conservation-restoration and reconstruction are not stages of a linear evolution in the critical evaluation of the monument; instead, they involve a dialogic interaction. These three methodological areas have defined since the early 20 th century the poles that describe a tension of the monument, which will be constantly re-evaluated based on the individual case of the monument and its balanced needs. The monument conceived aesthetically as an "image" which describes itself or is also conceived as an "image" that one makes of it is without doubt timebound. Only in understanding the "language" of the material substance one succeeds in redeeming these antipodes. It is quite obvious that our professional profile and ethics that are linked to "the materials" to be conserved were strongly supported for nearly 43 years by respective international institutions, theories, charters and codes of ethics, and last but not least by the general public. But very slowly, this support is vanishing also among the ICOMOS community. Some colleagues (Scheurmann, 2018) think that this is happening under the influence of the Burra Charta revised in 2013, but it is a real paradigm change -a sign of our time. The society-founded "roll-back" in the new millennium -away from a "value" and "substance"-oriented definition of monuments to an "image"-oriented one -seems to be, at least in Germany, the new consensus and a paradigm shift the implication. But conservatorsrestorers, conservation scientists and building archaeologists are committed in the first place to the historic substance and to the evolving or converted aesthetical appearance linked to it. Personally speaking, it happened to me in 2010 during a social evening event at an ICOMOS conference that I organised in Quedlinburg / Saxony-Anhalt: a colleague well-known worldwide confronted us with his spontaneous comment regarding the conservator-restorer's sole right to exist, which should be "prolonging the lifetime of material relics". His comment was: F*** the artefact! Highly sensitive colleagues were not so much shocked because of the drastic expression but because of the underlying bitter truth. Nearly seven years later and after two years of experiencing a new American (but not only American!) way of defining "truth" which forms a precedent, one can understand better this drastic, maybe sarcastic comment. Have conservators-restorers -who are finally at the height of their academic and professional evolution -become an endangered species? Will their natural habitat be soon destroyed by a quickly changing world of "Big DATA" and "Virtual Realities" and "Fake News"? At the moment, our profession suffers on the one hand from a difficult but still classical momentum of financial crisis, from a lack of political and public support, and from a less enthusiastic image among young people. On the other hand, the development of new relativistic theories considers this professional figure less indispensable than in the past. If you like, "materiality" is "old school", while "virtual reality" is the future. Together with the tasks of infotainment, storytelling, re-enactment, reconstruction, the creation of icons, etc., virtual reality is without doubt the new hype in conservation sciences and practice: digital inventories, documentations, hypothetic reconstructions, etc. have to have their legitimate function, but for some scholars this happens at the expense of the actually existing monuments. Especially architecture of the second half of the 20th century is endangered, because the quantity of this heritage is indeed immense -not only in Germany. While economic pressure and the often gigantic dimension of these buildings offer an easy pretext for heavy transformations or even total destruction and subsequent interpretation through so-called replicas, the scientific inventory or research on the original construction materials and their long-term behaviour have not yet really begun. Instead, the debate continues as to whether the design, the materials used or the construction techniques place these buildings outside the scope of normal conservation principles. In this regard, some monument conservation authorities postulate to give up the European tradition of "substance" in favour of the reproduction of the "idea" and the "iconic appearance" of these monuments. Arguments against their material preservation mostly repeat the common prejudices against monuments of the Modern Movement, which in the meantime have proven to be false, as for example: The use of experimental materials which won't last and were never thought to last over time; furthermore, thermal and acoustic insulation deficits are too difficult and too expensive to improve. For sure specific management and practical issues come up, but why shouldn't conservators-restorers be able to cope with them? What a good thing that the young generation has discovered in certain social network platforms the socalled "Ostmoderne" (or "Eastern Modernism") and the "Brutalism" in the architecture of the 1960s and 70s as a valuable aesthetic movement to be preserved materially (Danzl, 2016). The hashtag SOS Brutalism, a database supported by the Wüstenrot Foundation and the DAM (Deutsches Architektur Museum) has more than 50,000 followers! (SOS, 2017) Also, the ICOMOS International Scientific Committee on 20 th Century Heritage (ICOMOS 2017) focuses its efforts on buildings which are most at risk through lack of recognition and protection. This committee actively uses social media platforms for discussion and exchange of information and conservation initiatives. In 2014, the committee published the international standard "Approaches for the Conservation of the Twentieth Century Architectural Heritage" that is also known as the Madrid Document, which is currently being extended to include urban areas and landscapes (Madrid, 2014) The committee works in partnership with relevant regional and international organisations with an interest in 20 th Century Heritage, such as ICCROM and Docomomo (Tostões, 2002). Here comes the invitation to other conservatorsrestorers to get more involved in these institutions; for sure, your expertise will be warmly welcomed!

Résumé
Even if one had to start with a dystopia, one shouldn`t end with it, hoping that the proposed argument won`t become a self-fulfilling prophecy! As early as in 1979 in Western Germany, the most discussed argument by Stephan Waetzold and Michael Petzet was "Echtheitsfetischismus" (Waetzold, 1979), "authenticity fetishism " that Petzet changed in 1993 into the terminologically more correct "Substanzfetischismus", "fetishism of substance" (Lipp /Petzet, 1994) This obviously rhetorical question just revealed the dead end of a one-sided postwar discussion about the concept of "truth", "original" and "substance" in heritage conservation, marking the eternal dualism between "material and substance" and "aesthetical appearance". In 1994, the Nara Document on Authenticity offered indeed a pluralistic approach: The acknowledgement of "cultural heritage diversity" (Lowenthal, 2008) leads to authenticity judgements that may be linked to the value of a great variety of sources of information, such as: "Form and design, materials and substance, use and function, traditions and techniques, location and setting, spirit and feeling, and other internal and external factors" (Nara,1994).
The concept of "progressive authenticities", which means the layers of history that a cultural property has acquired through time are being considered authentic attributes of that cultural property. The challenge for the conservator-restorer is always to find the right balance! It is quite obvious that compromises between preserving the aesthetical appearance, maintaining the material properties and stopping the normal and unavoidable "wear and tear" at the same time have to be taken in account. The so-called "cultural turns" of the last three decades were named after Richard Rorty's programmatic "linguistic turn" of 1967 (Rorty, 1967). Rorty remarked the dependency of any form of knowledge on the dependency of language. The humanities focused on this concept with -the "material turn" in the 1980s (Bräunlein, 2012); -the "pictorial or iconic turn" in the 1990s; -and finally, the "holistic turn" in the 21 st century. These were surely not paradigmatic changes but shifts in perspective and new questions leading to the concept of inter-, multi-, or transdisciplinarity in conservation. So: anything goes in 2018? At the moment, the interpretative, negotiative and communicative aspects of conservation practice are widely discussed. Participation and communication are the keywords of this new approach to monument conservation. In the past 30 years, the concept of "reversibility" has turned out to be a "myth" (Petzet,1992). Reversibility doesn`t exist. So today we prefer to speak of a concept of "retreatability", which means that unavoidable interventions on a work of art -with sustainable materials and appropriate methods -should at least permit a re-treatment in the future (Appelbaum,1987). Conservation works must be understood as a responsible management of change. The use of appropriate methods and re-treatable materials of conservation must take into consideration both the support -understood here as the architectural structure -and the surface. Full documentation of all work undertaken is not an end in ITSELF, but a management tool and the base for corrective and preventive action (Pursche, 2015). This concept of "corrective and preventive action" is focused on systematic investigations of the causes identified degradation processes and is meant to prevent their recurrence or their occurrence. This can only be achieved by implementing an overall quality management system offering a regular and informed maintenance and care regime and a proper recording of any measures taken on the work of art or on the monument. At the end, some more comforting information should be given about the ongoing works at the Bauhaus buildings in Weimar and Dessau in preparation of the 100 th anniversary in 2019. On this occasion, the Wüstenrot Foundation provided some funds for a proper revision of the heterogeneous and discussed result of the1998 reconstruction of the so-called Master's House Kandinsky and Klee (Danzl, 1999). At that time, it was a kind of self-defense in order to prevent irreversible damage to the house during reconstruction work when the author prescribed that any treatment of the surfaces should be re-treatable to the greatest possible extent (Danzl, 2006,2). This was not only in order to preserve the authenticity of the handed-down historic surfaces -as a data store in situ -but also for the now possible option of repeated analyses and evaluations in the case of new problems or in fact additional knowledge. Building materials which at the time had been destined to be thrown away were then collected and stored by Monika Markgraf of the Bauhaus Foundation Dessau together with the author in an archive managed by the Bauhaus Foundation.
At the same time, a data base was installed to collect all available historic and material information regarding the Bauhaus buildings in Dessau and Weimar. 20 years later, these two types of data stores not only offer valuable possibilities for the conservation sciences and for the conservator-restorer to correct speculative reconstructions. They also provide authentic materials for repair works -as in the case of the unique floor coverings called "Triolin". Since in 1998 all the stratigraphic openings of the research work on the interior walls were conserved and mapped at a high standard before the buffer coating, new openings in 2017 could be limited to a minimum. After a first analysis of the pigments and colour hues, the spectacular colour scheme of the 1920s reconstructed in 1998 could be widely confirmed. Only a few colours were reproduced with an aged colour hue and during a recent investigation corrected. As time has shown, the path from theory to a commonly shared practice can be long and stony. Fortunately, the general attention that conservation specialists give to the importance of respecting the authenticity of materials during conservation-restoration has increased since then. However, without the material data stores the continuity of combining "real/analogue" and "virtual/digital" research work would have ended in an academic void. Hopefully, this success will be helpful in dealing with monuments of the second half of the 20 th century!