What is the interior exterior painting

Roman exterior painting and its history of restoration

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1 42 Nicole Riedl and Friederike Funke In an extensive restoration study, the entire collection of paintings has been viewed, analyzed and documented since 2008. 1 The original Roman exterior paintings have been preserved on a total of nine of the fourteen window axes of the lower row of arches on the west and north facades. In addition, there are around 65 m 2 of Roman plastered surfaces with sporadic remains on the north facade. North of the Alps, this in situ existing Roman facade design is unique in terms of both the recognizable quality and the existing quantity (Fig. 4-1, 4-2). Cut 3 to 3.5 cm. Particularly noteworthy are the setting joints, which are neatly drawn from top to bottom at an angle, so that the subsequent external plaster could anchor itself in this wall surface. The original sintered layers of the binding agent and the peeled burrs 3 from compacting the plaster with a trowel can be seen in numerous setting joints (Fig. 4-3). The round arches of the window closings have been placed over wooden support frames. The impressions of the former wooden boarding have been preserved as a negative in the setting mortar (Fig. 4-4). The very fat Roman setting mortar shows a characteristic off-white binder matrix with clear white lime galls Fig. 4-1: Overview plan: View of the north and west facade of the Constantine Basilica in Trier with the localization of the Roman exterior painting in the window reveals Fig. 4-2: Overview mapping: Original remains of the exterior painting and subsequent revision phases Roman masonry While the southern and eastern parts of the building date from the reconstruction period in the 19th century and the post-war years of World War II, the north and west façades of the Constantine Basilica are essentially original Roman masonry. This was built over a 4 m thick and up to 6 m deep foundation made of cast concrete 2. Some of the former wooden casing is still recognizable today as a negative imprint in the foundation mortar. A massive brickwork up to 3.40 m wide rises above it. The extremely carefully placed masonry consists of bricks that are 30 to 55 cm long and 4 to 4.5 cm thick. The joint height includes in it. In addition to rounded natural sands and gravels with large grains of up to 13 mm, fragments of bricks and white snail shells 4 can also be seen as an addition (Fig. 4-5). Facade design In Roman times, the brickwork of the Constantine Basilica was completely plastered with a three-layer mortar and painted in an off-white color. To emphasize individual architectural elements, both the arched niches and the building corners 5 in the transition to the apse vault were provided with a strong red frame.

2 43 Fig. 4-3: Roman masonry on the window axis W08-Süd: Joint line and peeled burrs from the compaction of the setting mortar can be seen Fig. 4-4: Imprints of the former wooden casing can be seen on the arches in the Roman setting mortar. Fig. 4-5: Roman masonry on the Constantine Basilica in Trier with its characteristic wide joints Fig. 4-6: The appearance of the Constantine Basilica in Roman times, an attempt at reconstruction. H&S Virtuelle Welten GmbH, Trier 2004, expanded Riedl 2010 Fig. 4-7 Remains of the base and middle plaster on the north facade with clearly legible trowel guidance in the base.Fig. 4-8: View of the middle and top plaster with heavily re-weathered surface

3 44 Fig. 4-9: Structural structure of the Roman mortar in the polished section Fig. 4-10: Fragment of the exterior painting from window axis W01 with red frame. The highlight of the facade decoration were the floral and figurative paintings in the window reveals (Fig. 4-6). Plaster application The concealed and middle plaster is each thrown on freely in a thickness of up to 20 mm and spread with the trowel back. While the concealed plaster is drawn vertically and clearly shows burrs, the middle plaster is provided with a smooth trowel. Individual trowel marks are not recognizable, the surface is determined by fine peeling ridges of the binding agent with a clearly recognizable direction of brushing (Fig. 4-7). The finishing plaster was only applied in a thickness of 5 8 mm and smoothed with a trowel. This step 6 is carried out extremely carefully and gives the entire polychrome decoration a perfectly leveled painting surface (Fig. 4-8). Through the Fig. 4-11: fragment back side with snail shells in the surcharge Fig. 4-12: Window axis W06, south reveal, reconstruction drawings of the painting and today's appearance, from left: Johann Nikolaus Wilmosky, drawing (mid 19th century); Lambert Dahm, drawing of the stock, black and white and color reconstruction (no year); Nicole Riedl, photo (2009) strong compression of the surface, the largest grains of the mineral aggregate are partially visible just below the paint skin. Mortar composition 7 In partial and thin sections, the individual mortar layers can be recognized by a sintered skin, which shows a clear break between the almost identically composed mortar layers. In the light beige, homogeneous binder matrix, there are clearly white and different colors

4 45 Fig. 4-13: Clearly recognizable plaster border in the southern window reveal W08 Fig. 4-14: Plaster border on the north facade with a few remains of the original exterior version Fig. 4-15: Detailed view of the Roman exterior version on the north facade Fig. 4-16 : View of the preserved Roman painting in the southern window reveal of the axis W06 Fig. 4-17: Strong red frame with clear traces of the paint application Fig. 4-18: Purple background of the painting with remnants of the gold-ocher tendrils, large calcareous galls with a rounded shape and numerous pores from. The bonding agent-aggregate contact is very good, there are no seam pores or cracks. Overall, the binder matrix is ​​colored off-white to light beige due to the colored fine components of the aggregate. The brown, red-brown, yellowish, gray, white and opaque aggregate consists primarily of quartz, little sandstone and granite. The surcharge is rounded and sanded, which points to Moselle sands and gravels up to recognizable grain sizes of 12 mm. In addition, there are occasional angular brick

5 46 Fig. 4-22: Adhering mortar residues from the former brickwork on the Roman exterior painting, window axis W08 Fig. 4-23: Remnants of binding agent from the already weathered masonry mortar on the intensely colored painting in the window axis W07 Fig. 4-19: Gold ocher-colored base tone of the painting with remains the strong orange shadow lines and light gray highlights Fig. 4-20: Detailed view of the gold-ocher-colored base tone of the painting Fig. 4-21: Remains of the white pearl rod in window axis W06, which were artificially added to the natural sand mixture. Their number is small, however, and it must be assumed that they were added as impurities during normal construction operations and not deliberately added (Fig. 4-9). A special feature are 6 to 12 mm large white snail shells, which are distributed in large numbers in the mortar. Fiber imprints and a few fiber residues as well as pieces of carbon are also present. The Roman mortar is characterized by good strength and stability (Fig. 4-10, 4-11). A total of 45% to 51% calcium carbonate can be found in the finishing plaster, with 2.0% to 28% magnesium-containing proportions (magnesite) containing 8 and 2.6% soluble silicon oxide proportions. This dolomite lime 9 was probably extinguished on the construction site using the dry slaughtering method 10. The numerous lime galls indicate this extinguishing technique. The mining sites for historical dolomite limestone are in the Trier catchment area in the West Eifel. 11 The binder-aggregate ratio is 1: 1 and thus represents a very rich dolomite-lime mortar. Roman painting The decorative exterior painting extends over the entire depth of the window reveal and consists of gold-ocher-colored floral tendrils and figural motifs that contrast with each other.

6 47 Fig. 4-26: Drawing by the Jesuit Alexander Wiltheim around 1610, the closed arched windows on the west and north sides are clearly visible. Fig. 4-24: Depiction of the Constantine Basilica as a fortified castle complex on a document seal from 1261 Fig. 4-25: Woodcut by David Kandel from Seb. Munster Cosmographia, state around 1580, richly contrasted with the purple background. The image is framed by a bright red frame and a white-gray bead rod (Fig. 4-12). Technologically interesting is the fact that the painting was applied directly to the finishing plaster that had just been stripped off, without applying a fine layer. The finishing plaster was perfectly prepared as a painting base thanks to the compression process, the binding agent lay as a fine layer on the plaster surface and in this way facilitated the fresco integration of the paint layers. Fig. 4-27: Clearly recognizable walling of the arched windows, drawing after 1610 very pure iron oxides with distinctive shades of ocher, red and red-violet. 12 Work process The three-layer plaster build-up was carried out from the apex of the arched window to the sill and is based on the Roman

7 48 Fig. 4-28: Representation of the renaissance extension on the remains of the Constantine Basilica and the Electoral Palace before the middle of the 18th century Fig. 4-31: Constantine Basilica from the northwest, view around 1870 Fig. 4-29: Documented condition around 1800, Drawing by Lange, steel engraving by Joh. Poppel Fig. 4-30: Inauguration of the Konstantinbasilika as Evangelical Church to the Redeemer on September 28th Reception of King Friedrich Wilhelm IV of Prussia by the community and clergy according to Principle 13 perfectly coordinated. Both the application of all three plaster layers, their respective careful chipping and their painting were carried out on each scaffolding level. The plaster boundaries are clearly recognizable from the window reveals under the arch field at three different heights. What is striking is the very low height of the lower layer of plaster, which also shows less stable color integration. Apparently the paint was applied too late, so that it could no longer completely set in a frescoed manner. 14 In the plaster levels above, the plastered surfaces were painted at the right time, because the color integration is much better (Fig). The sequence in which the paint is applied within the window reveals is the same on every scaffolding level and can be described as follows: First, the strong red, 10 cm wide frame on the edges of the reveal surface was painted with a brush. The traces of the ductus are clearly recognizable and with the placement of the first application of paint, the sizes of the purple background areas for the gold-ocher-colored tendril painting have been determined at the same time (Fig. 4-17). No scoring or other auxiliary structures have been used to maintain the field size. The purple surfaces were then painted. This background color has also been applied several times with a brush and then removed with a trowel. This process was repeated several times to intensify the purple tone. This step left clear peeling burrs from pigment and binder and also offered the ideal conditions for a fresco integration of the subsequent layers of paint (Fig. 4-18). The figurative and floral painting is initially laid out in a golden yellow basic tone and modeled with only one shadow and one treble tone. The shadow is executed in a strong, pure orange tone, the elevations today show a very light gray (Fig. 4-19, 4-20).

8 49 Finally, the transition area between the red frame and the purple background was decorated with a white bead rod (Fig. 4-21). History of restoration From the past 1700 years, traces of the varied history of use can be read directly on the building of the Basilica of Constantine, both in the purified interior and on the facade. In the Middle Ages, the building was transformed from the auditorium of a palace complex into a fortified castle and was later integrated into a four-wing Renaissance castle. It was not until the 19th century that the Constantine Basilica was converted into a church building with its current appearance. 16 By using written and pictorial sources 17, the revisions and repairs can be divided into the following five phases: Bringing up the arched windows 1st phase As a Roman repair phase could not be proven, the restoration history of the Roman painting and plaster remains begins with the conversion of the Building. This falls at the time of the fall of Roman rule in the provinces. After Trier was conquered by Germanic tribes in 407 AD, the imperial representative and executive building went into Franconian ownership for over 18. This change in function probably marked the first structural change, the palace complex and its auditorium fell into disrepair. Without a roof, but consisting of meter-thick walls, the hall became a castle. This had an open inner courtyard with access in the west facade and wooden fixtures along the walls. To increase the defensive strength of the building, the large Roman arched windows were walled up, as can be seen on images from the 11th century. In this covered and protected state, the paintings on the window reveals remained in the subsequent, changeable history of use up to the 19th century (Fig. 3-2,). To this day, the remains of the lime mortar used in the masonry can be seen on the painting. The mortar can be characterized by numerous slate-like aggregate grains and shows very good adhesion. The veil of binding agent lies heterogeneously and in itself broken on the surface of the painting. Well-preserved parts of the painting are clearly visible under the up to 2 cm thick mortar. This can be interpreted as a sign that the relics of the masonry protect parts of the painting to this day. At the same time, however, these also contribute to today's heterogeneous appearance and obscure the color impression of the decorative painting (Fig). Fig. 4-32: Basilica of Constantine 1924, partial view of the west facade Fig. 4-33: State of the Basilica of Constantine during the reconstruction after World War II, around 1953 Fig. 4-34: Basilica of Constantine, west facade in 1966

9 50 Uncovering the exterior paintings 2nd phase The paintings are only visible again from 1845, 19 when the large Roman arched windows on the west facade were reopened during the course of the reconstruction of the Constantine Basilica under the Prussian King Friedrich Wilhelm IV. In this second phase of conversion, extensive repairs were carried out on the facade, among other things. In the area of ​​the windows, the brickwork has been repaired and partially rebuilt. The paintings in the reveals were uncovered and examined for the first time. 20 The overall concept for the reconstruction of the Basilica of Constantine envisaged that the facade would be exposed to bricks, so that all the monochrome Roman exterior plaster that had remained up to this point in time was removed. 21 Only the polychrome paintings in the window reveals have been saved and preserved in situ. 22 Both the brick material used and the very careful application technique are characteristic of the supplementary phase of the 19th century. The repair masonry was executed with an exact joint line just below the bricks and thus has a dense, closed surface. Even small areas in the masonry were repaired with care by hand, with the original setting mortar being partially plastered over (Fig. 4-35, 4-36). The bricks are mainly in a light red similar to the original brick tone, with a matt surface. The associated setting mortar is characterized by a brown-beige matrix and a conspicuously fine aggregate mixture. The grain fraction 1 2 mm forms the coarsest part in the mortar. Largest grains of slate particles that can encompass mm are only found sporadically. White-yellowish chalk galls are also striking. The analysis results speak in favor of a converted lime gypsum mortar, with the current lime content being very low. 23 The Roman plastered surfaces were also secured and repaired with the characteristic brown-beige mortar, especially the connections to the windows that were newly installed at the same time. Here the repair mortar rests on the previously carried out additions to the masonry. All Roman plaster fragments were screeched at the edge areas and holes within the paintings were carefully closed. In addition, the same brown-beige mortar is spread over reweathered areas of the plastered surfaces, but in this case thinner, in a kind of slurry (Fig). Fig. 4-35: Example of the careful addition to the masonry from the 19th century Fig. 4-36: Repair mortar from the 19th century on a flaw in the window axis W03 Fig. 4-37: Example of a wing clip as plaster reinforcement Fig. 4-38: Grauer Cement-based repair mortar from the 1950s

10 51 Corresponding to the careful manual restoration of the paintings, the work was documented and described for the first time in the middle of the 19th century. The first reconstruction drawings by Wilmosky date from the same time.24 According to reports, in 1923 the paintings could still be clearly seen with the naked eye, but only 13 years later the exposure to the elements had destroyed the paintings considerably. 25 Stabilization with wing clips 3rd phase The third phase must have taken place after 1856, but before World War II. Written sources document considerable moisture damage 26 to the Constantine Basilica around 1929, the restoration of the copper roof in 1930 and the relocation of the waste pipes. 27 Characteristic of this phase is the careful repair of the painted external plaster with reddish slopes and the use of metal wing clips. These clips were attached to the edge areas of the original plaster and prevented the plaster from falling. Little repairs were made to the masonry itself (Fig. 4-37). The repair mortar used is characterized by a reddish matrix and a high addition of brick chippings. Its smooth surface structure can still be seen in protected areas, which makes the repair mortar appear hard and compact. The binder matrix is ​​lost in reweathered areas and the colored aggregate can be seen. In addition to the edge slopes, the imperfections within the plastered areas were added and the mortar was drawn over the edges of the imperfections in a kind of sludge. In the process, thick tracks were created in places that lie on the original surface. In addition, a surface strengthening with water glass 28 was carried out at that time. This is particularly recognizable in the window niches W6-South and W4-South by a partially preserved transparent layer on the surface. This coating shines in the backlight, is colorless, brittle and chemically inert and is present as a broken and cracked layer. The consolidation measure 29 cannot be documented in the written sources at the current state of the archival investigations, but due to the sequence of layers it should be located before the repair phases of the post-war period. The strengthening of water glass has led to a compacted glass layer in the near-surface area of ​​the paint layer and plaster and is now visually shown by graying. The glass film is very finely torn, moisture accumulates and leads to an overall visual impairment. Repairs after the 2nd World War 4th phase During the 2nd World War the Constantine Basilica was badly damaged. Dealing with the remains of the building led to intensive Fig. 4-39: Yellowed and torn protective coating from the 1950s on window axis N11 Fig. 4-40: Microscopic view of the polyester paint from the 1950s Fig. 4-41: Removed using the Stacco technique Roman exterior painting of window axis W01 public discussions. In 1953, the state of Rhineland-Palatinate, as the legal successor to Prussia, declared its willingness to completely rebuild the Basilica of Constantine. 30 In the course of this fourth repair phase, the brickwork was repaired on the entire building, new windows were installed and the Roman plaster fragments were secured with their paintings. The repair masonry from the 1950s can be recognized by the strong dark red bricks that are around 20

11 52 are 25 cm wide and have a smooth, sintered surface. Characteristic are flush joints without a joint line. A lime-cement mortar with the addition of gypsum was used as the setting mortar, which is characterized by a brown-gray to brown matrix. 31 The surface of the setting mortar was peeled off rough and open so that the aggregate is partially visible. The colorful aggregate of sand and pebbles with rounded edges shows a high proportion of fine grains in the size of 1 2 mm, a high proportion of medium grains of 2 4 mm and a few large grains of up to 13 mm. In contrast to the previous phases, this is noticeable due to a lack of care in execution (Fig. 4-38). A cement-bound mortar corresponding to the setting mortar was used to secure the Roman plaster fragments. Especially along the newly installed windows and on the outer edges of the Roman plaster, thick embankments were made. The surface design of the supplementary plasters was partly based on the original findings. A smooth and tightly peeled surface was cemented to the level of the paint layer, while Roman plaster surfaces that had been weathered back were troweled off in a rough and open manner. However, this system was not followed consistently. Rather, it seems that several hands have carried out the repair work more or less carefully and the original was also cemented in numerous places. To secure the paintings, the surface was sealed relatively uniformly with polyester varnish. 33 To this day, this setting clear lacquer has been preserved in the window niche N11 on the north apse as a thick, yellowed layer on the surface. Today he shows strong signs of aging and is torn. The Roman paint layer underneath has been softened and is torn off from the plaster substrate by flakes of paint standing up (Fig. 4-39). In the window axes W6 to W9, residues of the polyester lacquer can also be seen, which, however, are not preserved in the same layer thickness as in N11. The residues described are only detectable in thin layers. The former film has broken open and torn within itself. In the microscopic picture, however, you can still see the shiny and dense structure of the film residues. In the southern section of the west facade from W3 to W5, a layer of paint is no longer visually recognizable. In summary, it can be stated that the layer thickness and areal distribution of the coating increase continuously towards the northern area of ​​the west facade. This means that the degree of weathering is significantly increased along the west facade in the south in contrast to the northern area (Fig. 4-40), attempts have been made to remove the Roman paintings in the window axis W1, 34 on the assumption that they can be preserved in the long term . The applied Stacco technique 35, acceptance of the wall painting including the finishing layer, was unsuccessful. The paintings of the window axis W1 broke into numerous fragments and are now stored in the State Museum in Trier (Fig. 4-41). 36 The remaining Roman originals were then left in situ on the facade of the Basilica of Constantine. Small repairs to the paintings 5th phase In places, another patch mortar with a characteristic gray color and a very fine structure lies on top of the cement-bound mortar from the 1950s. It runs rough, uneven and with smeared plaster ridges over the cracks and holes in the contact areas of the original plaster and repair plaster and has been used on a rather small scale. Written sources are currently not available for this verifiable repair phase. Conclusion Every repair and conversion phase has left traces on and on the fragments of the Roman facade design and continues to influence them to this day. It must be emphasized that all materials and techniques used for 150 years should ensure the permanent preservation of these. However, the history of the conservation of wall paintings shows that any conservation material can also have a damaging effect. The later added materials plaster of paris, water glass, cement and polyester varnish interact with the originally installed materials and, increased by the free weathering of the west facade, contribute to the fragile state of the plaster fragments today. Photo credits Nicole Riedl:,, Rheinisches Landesmuseum Trier:, Stadtbibliothek Weberbach / Stadtarchiv Trier: 4-24 Illustrierte Zeitung No. 696 from November 1, 1856: 4-30 Photo collage Nicole Riedl: 4-12 (comparison of the paintings window axis W6 from different times ; Drawing by Johann Nikolaus Wilmosky, published by Hettner p. 243; redrawing and colored drawing by Lambert Dahm RLM Trier, plan no. No. And no.; Photo: Nicole Riedl 2009) Literature Michael Auras, introduction, in: Umweltbedingte Building damage to monuments through the use of dolomite lime mortars, Institute for Stone Conservation ev, report no.16, Mainz 2003, p. 1 3 Wolfgang Binsfeld, Porta Nigra, basilica and amphitheater in Trier in medieval sources, in: Landeskundliche Vierteljahresblätter, 23, 1977, S Rainer Drewello R. Rudolf Weissmann, analysis result AN 2083, unpublished research report, Bamberg 2010, S Lambert Dahm, Trier. City and life in Roman times, Trier 1991 Lambert Dahm, Trier. City and Life in the Middle Ages, Trier 1997

12 53 Sabine Faust, basilica: Römische Palastaula, in: Jürgen Merten (ed.), Guide to archaeological monuments of the Trier region (series of publications by the Rheinisches Landesmuseum Trier 35), Trier 2008, p. 42 f. Thomas Fontaine, A last reflection of the past imperial splendor. On selected archaeological findings from the area of ​​the Roman imperial residence in Trier, in: Margarethe König (Ed.), Palatina, Kaiserpaläste in Konstantinopel, Ravenna and Trier, Trier 2003, S Klaus-Peter Goethert, Basilika, Römische Palastaula, in: 2000 years City history Trier: The new city guide, Trier 2010, S Klaus-Peter Goethert, Die Basilika, in: Trier (Guide to prehistoric and early historical monuments 32), Vol. 1, Mainz 1977, S Guido Hepke, Destruction and Reconstruction, in: Auf Ewige Times, the history of the Constantine Basilica, Trier 2008, S Felix Hettner, To the Roman antiquities of Trier and surroundings II. The so-called basilica, in: West German magazine for history and art, 10, 1891, S Annual report of the Provincial Museum in Trier. Excavations, finds and acquisitions. From April 1, 1929 to March 31, 1930, in: Trierer Zeitschrift 5, issue 4, 1930 Harald Koethe, Die Trier Basilika. Trier magazine 12, 1937, S Karin Kraus Stefan Wisser Dietbert Knöfel, On the slaking of lime before the middle of the 18th century, literature evaluation and laboratory tests, in: Arbeitsblätter für Restauratoren, H. 1, 1989, S Hans-Peter Kuhnen (Ed. ), The Roman Trier (Guide to Archaeological Monuments in Germany 40), Stuttgart 2001, S Friedrich Kutzbach, The large Roman buildings in Trier, Trierische Landeszeitung, No. 184, August 10, 1937 Trier imperial residence and bishopric. The city in late antique and early Christian times. Exhibition cat. Rheinisches Landesmuseums Trier, Mainz 1984 Trier annual reports, annual report of the Society for Useful Research in Trier, 1, 1909 Heinz-Otto Lamprecht, Opus Caementitium, Bautechnik der Römer, 3rd edition, Düsseldorf 1987 Wilhelm von Massow, Die Basilika in Trier (Hunsrücker Series B; Scientific Series 1), Simmern 1948 Paolo Mora Laura Mora Paul Philippot, The Conservation of Wall Paintings, London 1984 Jürgen Pursche, Medieval Plastering Comments on Findings in Regensburg, in: Colored Architecture: Regensburg Hauser Building Research and Documentation (Bavarian State Office for Monument Preservation Workbook 21), Munich 1984, S Jürgen Pursche, Historical Plastering Findings in Bavaria. On their typology, technology, conservation and documentation, in: Art Technology and Conservation 2, H. 1, 1988, S Wilhelm Reusch, The external galleries of the so-called basilica in Trier, in: trier magazine 18, 1949, S Wilhelm Reusch, Aula Palatina in Trier, in: Germania 33, 1955, S Wilhelm Reusch, The Konstantinische Palastaula in Trier, in: New excavations in the Middle East, the Mediterranean and in Germany. Report on the conference of the Koldewey Society in Regensburg from April 23 to 27, 1957, Trier undated, S Wilhelm Reusch, The Roman basilica as the palace hall of Emperor Constantine the Great, in: Konstantin-Basilika Trier Church of the Redeemer, Trier 1999, S Nicole Riedl, preliminary study for project planning: inventory of Roman external plastered surfaces, unpublished conservation reports,, available: Landesbetrieb Liegenschafts- und Baubetreuung, Trier branch Nicole Riedl, provincial Roman wall painting in Germany, history of historical materials, technology, restoration history in the context of monument preservation, illustrated by selected examples, Bamberg (2007) 2010 URN: urn: nbn: de: bvb: 473-opus-2185 URL: Frank Schlütter, MPA Bremen, unpublished analysis report on the ocher pigments used at the Konstantinbasilika, Bremen 2012, p. 1 6 Kurt Schönburg, Gestalten mit Silicate paints, Halle 1987 Heiner Siedel Steffen Michalski Hans-Werner Zier, burning, extinguishing un d hardening of dolomite limestone, in: Environmental damage to monuments caused by the use of dolomite lime mortars, Institute for Stone Conservation ev, report no.16, Mainz 2003, S Peter Steiner, report on the activities of the Provincial Museum in Trier from to, in: Bonner Jahrbücher 129, 1924, S Jan Werquet, The reconstruction of the Trier Konstantinbasilika under Friedrich Wilhelm IV. The planning and building history, in: Trierer Zeitschrift 65, 2001, S Eberhard Zahn, Die Basilika. Evangelical Church of the Redeemer Trier, Trier o. J. Eberhard Zahn, The basilica in Trier. Roman Palatium Church of the Redeemer (series of publications by the Rheinisches Landesmuseum Trier 6), Trier 1991 Eberhard Zahn, The Trier Basilica and the German Romanticism, in: Trier Journal 54, 1991, S Riedl 2008, Preliminary study for planning: Inventory of Roman plastered surfaces, Hallstadt Lamprecht 1987 , P. 174: opus caementitium; Zahn 1991, p. 31 speaks of clad concrete. 3 Cf. Riedl 2010, photo part glossary: ​​Smoothing, Abziehgrate Blatt Recent gastropod housing, 6 12 mm in size, included in the surcharge.

13 54 5 This finding is only verifiable on the north side of the Constantine Basilica. 6 Finishing plasters of this kind that have been denser and smooth have so far only been found in representative interior decorations in the Roman provinces, see Riedl 2010, p. 188 ff. 7 The analysis of the original mortar and the supplementary mortar was carried out using various methods of determination: In addition to light microscopic analyzes of cyclododecane sections, wet chemical analyzes were also carried out Analyzes carried out. Laboratory Drewello Weißmann carried out additional analyzes with the help of X-ray diffractometry (XRD), FT-IR microspectrometry (IR, diamond cell preparations) and SEM-EDX. 8 The results relate to wet chemical analyzes, analyzes using carbonate bombs and X-ray diffractometry with data in M%. 9 Definition and properties of dolomite lime see Siedel et al. 2003, S cf. Pursche 1984, p. 11 f .; Pursche 1988, p. 8 f .; Kraus et al Auras 2003, S Drewello Weissmann 2010; Schlütter See also Riedl 2010, S This zone can be related to the proven circumferential gallery and would therefore be regarded as a dirt base. It may therefore have been treated differently than the rest of the painting areas. See also Fontaine 2003, S There is evidence that very pure, natural iron oxides in strong colors (red, violet, orange and golden yellow) were used as pigments for Roman painting, Schlütter Hettner 1891, S; Zahn Binsfeld For the eventful history of the Constantine Basilica, compare v. a. Goethert 2010, p. 24 f .; Faust 2008; Fontaine 2003; Kuhnen 2001; Werquet 2001; Reusch 1999; Dahm 1997, p; Dahm 1991, p; Zahn 1991; Goethert 1977; Binsfeld 1977; Reusch 1957; Reusch 1955; Massow 1948; Reusch 1949; Koethe 1937; Kutzbach 1937; Annual report of the Provinizalmuseum zu Trier 1930, S; Steiner 1924; Trier annual reports 1909, p; Hettner Hettner 1891, S Ferdinand von Quast recognized the extraordinary value of the paintings and campaigned for their preservation, see Werquet in this volume. 21 Werquet 2001, S Black and white drawing by Johann Nikolaus Wilmosky, see Fig. Drewello Weissmann 2010: Sample 09-03: The mortar is relatively soft and does not react with acids. The FTIR and XRD analysis results speak for a converted (lime) gypsum mortar, whereby the lime content is very low today. 24 Wilmosky's drawings were first published by Hettner in 1891, p. 243. 25 Massow 1948, S Steiner 1924, S Annual Report of the Provincial Museum in Trier 1930, S Drewello Weissmann 2010: Sample 09-01: The particles consist of a red or dark red layer of paint with a transparent coating that has a brownish surface in places. The coating is colorless, brittle and chemically inert. The main components of the coating are silicates, which belong to glasses (amorphous silicates) and are interspersed with gypsum (thin layer). Accordingly, a water glass or silicic acid ester treatment should be present. The silicate has accumulated on the surface in places. Small traces of an organic additive and iron oxides / hydroxides rather indicate treatment with a water glass. The preservation layer is formed over by the secondary incorporation of plaster of paris. 29 Water glass was rediscovered by Johann Nepomuk Fuchs in 1825 and was manufactured in the factory from 1889 as a binding agent for permanent wall paintings with the trade name Keimsche Mineralfarben, see Schönburg 1987, S Hepke 2008, S Drewello Weissmann 2010: The light gray to brown-gray, very stable mortar is a lime-cement mortar with the addition of gypsum and secondary corrosion products. Ettringite (sulfate expansion) can be detected in traces. Ettringite is created in cement stone by the fact that gypsum is attached to calcium aluminate hydrate. 32 Friendly verbal communication by Lambert Dahm Drewello Weissmann It is a brittle and chemically extremely stable, cross-linked unsaturated polyester (UP). The product range was in the 1960s under the name Leguval and is considered one of the most chemically stable products that have been developed. Manufacturers were, for example, Bayer Leverkusen and Vosschemie Uetersen.Further product names and trade names are: Aldenol, Laminac, Palatal, Vestopal, Diolen, Trevira, Dokulux. 34 Kind verbal communication Karin Goethert Cf. Mora et al. 1984, S inventory number RC