Edge impact (architecture)
Edge hitting , also hemming hitting , describes a flat strip on the edge of a stone block in the stonemasonry art.
In the art of stonemasonry, flat strips along the edges of stone blocks are known as edge chipping. Dragging the edges is the first step in the manual processing of natural stone surfaces . The further processing of the mirror (the area between the edge cuts) determines which function the edge cuts fulfill. A distinction is made between flat, raised and recessed mirrors.
To produce even surfaces, the protruding bosses are worked down to the depth of the edges. The edge joints fulfill an auxiliary function in flat ashlar masonry and, together with the mirror, form the finished surface. The edge flap can remain visible (Fig. 1) or be processed like the mirror so that it can no longer be distinguished from it (Fig. 2).
In the case of boss blocks , the boss stops or is processed, but not to the depth of the edge strokes (Fig. 3). In this case, the edging fulfills both a technical and an aesthetic function:
- The edge cuts make it easier to move the cuboids vertically, as the edges of the edge cuts are flat.
- If only the edge strokes have to be drawn and the boss stops or is only changed slightly, the processing time is reduced accordingly.
- The masonry bond of the façades is clearly emphasized by the edge joints despite the tight joint connection at the horizontal and butt joints , so that the interplay between the joint pattern and bosses can develop its aesthetic effect.
The anathyrosis procedure made it possible to minimize the work of the stonemason when working on the bearing and joint surfaces. The structural elements were provided with edge joints and the bosses roughly worked off to below the edge joint level, so that a recess resulted that did not impair the joint closure of the edge joints (Fig. 4). Anathyrosis was not only applied to stone blocks, but also to the processing of column drums .
Anathyrosis was invented in Egypt in the Old Kingdom . In ancient Greece it was widespread and was also used in ancient Roman architecture.
In the specialist literature, the term Randschlag is not used in connection with anathyrosis, rather paraphrases are used, e.g. B. Contact surface, hem, connection surface, edge strips.
Number of edges
To create a flat mirror , the surface of the cuboid is provided with a circumferential edge fold (four-sided edge fold).
For cuboids with a raised mirror (boss cuboids ), the number of edge strokes can vary between 0 and 4. With a four-sided edging, the distance between two bosses doubles and the joint seal remains visible. With two or one-sided edges, the butt or horizontal joints can be set so that they coincide with the boss edge and are therefore almost invisible. This is e.g. B. desirable in the production of tape rustics or when several cuboids are apparently to be connected to one cuboid at the butt joints.
Example: In Fig. 5 you can see three layers of stone above the base cuboid, which are designed as band rustics . The distribution of edge impacts can be seen from the horizontal joints in the door frame:
Due to this distribution of the edge folds there is only one edge fold between two cuboids. This has the advantage that the mortar joint remains invisible when viewed from above because it is not located between two edge cuts.
Edge impact width
The width of the edges of ashlar stones with a flat and raised mirror varies between very narrow (up to 1.5 cm), medium-wide (approx. 2.5 cm) and very wide (rarely more than 5 cm). Numerous individual data on edge widths can be found in Friederich 1932 (German and Alsatian churches) and Eckert 2000 , pages 49–118 (Florentine profane buildings from the Duecento ). In ancient Greece, the edges of blocks without anathyrosis were between 0.5 and 3 cm wide.
The edge impacts are usually the same width for the same type of cuboid in a masonry, but there are also variable edge impact widths. At the Torri dei Galigai z. B. the edge width varies from 1 to 4 cm, at the Palazzo dei Cerchi from 0 to 2 cm and at the Palazzo da Uzzano from 2 to 5 cm (all buildings in Florence).
In the case of structural members with anathyrosis , the edge impact in ancient Greece was initially 7-10 cm wide, in the Hellenistic period 11-20 cm.
False margin strikes
The application of new techniques meant that “the edge cuts lost some of their functional significance for vertical displacement” and could therefore serve as a “stylistic element in the design of associations”. By subsequently knocking out vertical channels into the visible surface, the cuboid was apparently divided into several cuboids. The canals, which are usually not cut at the edge, and thus do not coincide with the butt joints, simulate edge blows to the viewer.
The following description shows one of the common methods of manually pulling quadrilateral margin strokes.
- Benches . The stone to be processed is placed on a hooded bench ("benched") so that the surface to be processed is horizontal and points upwards. In Figure 6, a second stone cuboid serves as a dome bench.
- First longitudinal stroke. A straight edge is laid on one side of the stone below the lowest point of the surface . Mark a horizontal line along the straight edge with a sharp edge of the iron . Above this line, a flat track is drawn with the hammer (Fig. 6a). The evenness of this edge run is checked with the straight edge and corrected until the straight edge is completely flat.
- First cross passage. In the plane of the first longitudinal pass, a cross pass is now drawn at right angles (Fig. 6b).
- Target. The stone must be sighted so that the second cross pass at the other end of the stone is level with the first two passes (Fig. 6c, Fig. 7). This is done with the help of two straight lines. One is placed upright on the finished cross passage; the other is held against the stone on the opposite side so that its lower edge coincides with the end of the longitudinal stroke. By lowering and lifting this straight edge at the free end, it is now set in such a way that the upper edges of both straight lines coincide when aiming in. If this is correct, the fourth corner point is marked on the corner of the stone that has not yet been processed.
- Remaining edge blows. Now, in the same way as the first pass, the second cross pass and then the second longitudinal pass are drawn (Fig. 6d). Figures 6e and 6f show two of the work processes that are used to work off the boss (protruding part between the edge cuts).
|German||the edge fold, the hem fold|
The word Randschlag means:
- the stroke along the edge of a stone block
- and figuratively the result of this activity.
- Dieter Arnold : Building in Egypt , New York 1991, p. 123.
- Anja Eckert: The Rustika in Florence: Medieval masonry and stone processing techniques in Tuscany , Braubach 2000, especially pages 44–45.
- Dorothee Elias: Working on a stele made of shell limestone: From design to determination , Mönchengladbach without a year, only online .
- Reiner Flassig: Historical stone processing , page 310 ff. In: Education center for the stonemasonry and sculptor's craft (ed.), Steinmetzpraxis, The manual for daily work with natural stone, 2nd revised edition, Ebner Verlag, Ulm 1994. ISBN 3-87188 -138-4 .
- Robert Habermayer: Masonry technology and stone processing of the Romanesque period in the former diocese of Minden , Hanover 1983, pages 77-80, 85.
- Dorothea Hochkirchen: Medieval stone processing and the unfinished capitals of the Speyer Cathedral , Cologne 1990, pages 34–39.
- Christoph Höcker : Metzler Lexicon of Ancient Architecture: Things and Concepts , Stuttgart 2008, keywords "Anathyrosis" and "Randschlag".
- Werner Müller (text); Gunther Vogel (panels): dtv-Atlas zur Baukunst, Volume 1: General part: Building history from Mesopotamia to Byzantium , Munich 2005.
- Wolfgang Müller-Wiener : Greek architecture in antiquity , Munich 1988, pages 75-76, 90 (anathyrosis), 78 (edge impact).
- NN: Small Dictionary of Architecture , Stuttgart 1995, keywords "anathyrosis" and "Randschlag".
- Wolfgang Rudolph: Knocking stones for home use: Interested parties can gain insight into the secrets of the stonemasonry at Trebsen Castle in Saxony . In: Bauernzeitung from August 7, 2009, pages 68-69.
- Fritz Scheidegger: From the history of building technology, Volume 1: Basics , Basel 1994, page 157 ( Google book ).
- Michael Senn: The workshop orange technical term lexicon (7-10): Randschlag I-IV . In: Campos: Zeitung für Landschaftsgärtner 2008, Issue 11, to 2009, Issue 2,  (PDF; 132 kB),  (PDF; 129 kB),  (PDF; 121 kB), [4 ] (PDF; 127 kB).
- Peter Völkle: Work planning and stone processing in the Middle Ages . Ebner Verlag, Ulm 2016. ISBN 978-3-87188-258-6 .
- Albert Burrer: The stonemason at work , Stuttgart 1911, pages 7–8.
- Joseph Claudel; L. Laroque: Pratique de l'art de construire , Paris 1859, pages 287-288 ( Google book ).
- Josef Durm : Handbook of Architecture, Part 2: The architectural styles. Historical and technical development, Volume 2: The architecture of the Etruscans. The architecture of the Romans , Darmstadt 1885, pages 128–130 ( digitized version ).
- Karl Friedrich: Stone processing in its development from the 11th to the 18th century , Augsburg 1932, reprint Ulm 1988, page 26, 36–37 and passim .
- Theodor Krauth (editor); Franz Sales Meyer (editor): The building and art work of the stone mason, Volume 1: Text , Leipzig 1896, pages 185–188, 205–206 ( Google book ).
- Theodor Krauth (editor); Franz Sales Meyer (editor): The building and art work of the stone mason, Volume 2: panels , Leipzig 1896, panel 1.
- William Dwight Whitney (Editor); Benjamin Eli Smith (Editor): The Century Dictionary, Volume 2, New York 1911, page 968 online .
- Leo von Willmann: working stone . In: Otto Lueger (editor): Lexicon of the entire technology and its auxiliary sciences , Volume 8, Stuttgart 1904, pages 917-918 ( online ).
- Ludwig Friedrich Wolfram: Complete textbook of the entire architecture, Volume 1: Doctrine of building materials , Stuttgart 1833, page 175 ( Google book , Table VII Google book ).
- Raised part of the surface between the edge cuts.
- Wolfram 1833 , page 175.
- The “Temporal overview of the types of processing” in Friederich 1932 , pages 36–37, provides numerous references to images of visible edge cuts on stone surfaces in the “Character sample image” column.
- "The terms humpback cuboid and boss cuboid are used synonymously for stones whose visible surfaces protrude from the wall plane." ( Eckert 2000 , page 11). The bosses can take various forms (e.g. pillow, cushion, diamond, plate).
- Eckert 2000 , page 44.
- Höcker 2008 ; Müller-Wiener 1988 ; Wikipedia article Anathyrosis ; Reclam 1995 .
- Arnold 1991 .
- Eckert 2000 , pages 44-45; Krauth 1896.1 , pages 205-206; Krauth 1896.1 , plate 1.
- Classification according to Friederich 1932 , page 37, printed in the treatment of natural stone surfaces .
- Müller-Wiener 1988 , page 77.
- See Italian Wikipedia: Torri dei Galigai .
- See Italian Wikipedia: Palazzo dei Cerchi .
- See Italian Wikipedia: Palazzo Capponi alle Rovinate .
- Eckert 2000 , pp. 52, 55, 92.
- Müller-Wiener 1988 , page 75.
- See e.g. B. the facade of the Palazzo Rucellai ( Eckert 2000 , page 103); Tomb of Caecilia Metella ( Durm 1885 , page 130).
- Burrer 1911 ; Eckert 2000 , page 44; Friederich 1932 , page 26; Habermayer 1983 ; Hochkirchen 1990 ; Krauth 1896 ; Scheidegger 1994 ; Wolfram 1833 .
- The process of "fleeing" can be described by the following words (one source is given in brackets): Visieren ( Wolfram 1833 , page 175), Einvisieren ( Scheidegger 1994 ), Ersehen ( Hochkirchen 1990 , page 424), Versehen ( Burrer 1911 , page 8), reticle ( Habermayer 1983 , page 79).
- Almost literally after Krauth 1896 .
- Whitney 1911 .
- Claudel 1859 , p. 288; Wiktionnaire: ciselure .