|
|
||
|
|
|
|
|
 |
Udvalgte artikler:
|
|
A Swastika Fibula from the Engbjerg Cemetery
By Anders Ekstrøm LøkkegaardIn 1998 The County of Copenhagen Museum Council (now The Museum at Kroppedal) excavated an Early Roman Iron Age Cemetery at Engbjerg in the parish of Høje Taastrup, (Note 1). 25 graves were found, of which several were remarkable in that they contained many and rich grave goods. Many of these were lifted from the graves still encased in the surrounding clay by means of wooden frames or plaster, a so called "mount", (Note 2). Three were sent to Sydjysk Konserveringscenter in Gram (Southern Jutland), where the surface was fixated with paraffin wax and the mounts X-rayed, (Note 3). They were then sent back to the conservation laboratory of The County of Copenhagen Museum Council. In order to obtain a three-dimensional effect further X-ray photographs of all three individually were taken, applying the same method to all of off-setting the mount approximately 10 cm to either side of the center. After development the X-ray exposures could then be studied in a stereoscopic viewer. One of the mounts contained among many other things a Swastika Fibula. Both Anette Adomat´s and my own X-rays showed that the Fibula was in a state of advanced deterioration. Conservator E. Benner Larsen carried out the technological examinations. Excavation and Conservation of the Swastika Fibula
After the removal of the paraffin wax it became apparent that the block as a whole had shrunk by about 5 percent. Unfortunately, a considerable shrinkage crack went right through the area where the fibula was sitting. Re-moisturization was attempted, but had to be given up because of the clayey material. Subsequently the object was sketched and photographed several times as the process went along. The fibula was lying upside down. The first thing to appear was the woman's right collarbone, which had fallen on top of the fibula. After the lifting of the collarbone the following could be observed: Spring holder, spring, pin, pin holder and base plate. All component parts were of bronze and the base plate was broken into 12 fragments. The individual parts were mechanically cleaned with a surgical knife under microscope and kept on trays in Plexiglas climatic cabinets at low humidity. Following examinations the bronze parts were treated with inkra lacquer/ toluene in vacuum and the base glued with cyanoacrylat adhesive. 
By now it was possible to look down into the center rosette. There the bronze center rivet was visible together with the undersides of three bent bronze plates whose purpose would have been to support the lid of the center rosette and to prevent it from being pressed inwards. The bronze support plates were fixed with Japan paper and polyvinylbutural (Pioloform) 10% solution in water. Almost all the silver thread rings were now visible. Some were lifted and some were fixed, also with pioloform 10% in water. The center rosette was filled with glass pellets, and undercuttings were removed with wet paper. Paper was placed on the surface and covered with foil. Strips of paper saturated in stearine were stuck onto the surface until a suitable thickness had been achieved, and a sturdy cardboard disk was attached to give the new "mount" a stable base. In this new state - consisting of considerably less clay - it was then turned over and excavated. 
The gilt rosette silver foil, the gilt silver foil plates, the many rivet heads and silver thread rings were registered and lifted. The top plate of the center rivet was consolidated with inkra lacquer/toluene. A long series of X-ray exposures now followed in the search for silver sulphide rivet heads, and 45 out of 51 were detected. Of the 4 bronze rivet heads of the hemi-spherical rosettes only 2 were present. In the lifting of the individual parts and components it was essential to describe some stationary characteristics. It would not do to describe the orientation on the basis of corrosion products alone, as it could not in advance be taken for granted which final appearance the fibula would present. That means that as far as the silver thread rings were concerned the only way to orientate them was by means of the angle between the thread ends. Characteristic of this fibula is that all the silver thread rings are turned with their openings facing the opposite side in the squares of the fibula. The orientation of the gilt rosette silver foil was less complicated. In addition to describing the individual parts in writing and registering them photographically, they were marked on a sketch of the base. Silver threads in red, and gilt silver foil in green. All the silver threads had originally been ground flat where they were soldered onto the basis. This was done in order to obtain a larger contact surface and thus enhanced soldering efficiency. Now followed the cleaning of silver threads, gilt silver foil and rivet heads. They were brushed using a marten-hair brush in deionised water followed by the same treatment in EDTA 0.1 M, pH approximately 11 with NaOH. Finally watering-out in deionised water and dehydration in undiluted ethanol. Using this process it was possible to remove easily soluble salts and not silver sulphide. 
Deionised water was used to dissolve the layer between the bronze ring and the side silver foil of the center rosette. The bronze ring and the silver thread ring were lifted. The center rivet was taken apart into the three bronze support plates, the center rivet and the lid. The bronze parts were cleaned mechanically under microscope and treated with inkra lacquer/toluene in vacuum. The silver thread ring, the gilt side silver foil and the lid underwent the same treatment as the above-mentioned silver and gilt silver foil component parts. Early in the process were discovered - close to the fibula - a dentated, round and gilt silver-foil leaf with holes in it, and two small and short bits of silver thread. These three parts have presumably been attached to the top plate of the center rosette, as they fit in with the diameter of it. Considering the outstanding esthetical excellence put into the making of the swastika fibula it makes sense that - having been designed to be seen from above - it was entirely inlaid with gilt silver foil with surrounding silver threads. On its most prominent part, at least. 
Before commencing the actual re-assembling of the fibula an attempt to remove the silver sulphide was made, by using limestone powder and gilding chalk, but unsuccessfully. Also grinding of a few selected places showing a pure silver surface. This was done to ensure that there were no cases of silver re-crystallization on top of the gold, but the gold has been worn off during polishing in ancient times. This would also be in accordance with the progressed wear of the silver thread rings. The piece would have been well used and rather worn, when the woman got it with her in the grave. Considering the relatively poor results of the grinding treatment the silver thread rings were sandblasted with glass pellets and using very low pressure in the blasting gun. Upon completed examinations the silver thread rings were coated with a weak solution of paraloid B 44 in ethanol in order not to corrode. At that point in the conservation process a need for more adequate photographic registration facilities arose. A Hasselblad camera was therefore acquired, and a photo studio furnished, whereupon the re-assembly proper of the fibula could commence. For this nitrocellulose adhesive was employed, and by means of X-rays, photos, drawings and descriptions the component parts could be re-mounted. 
Right from the outset a logbook was kept of the excavation, notes of positions, steps in the process and contemplations. That is absolutely essential, as it is not possible to include everything in a photo. Particularly advantageous was the fact that the fibula was almost completely broken up in its individual component parts. Why this was so is unknown, but it is likely that the quality and amount of the solder used has caused a repulsion of silver components from the bronze. Gilt rosette silver foil "one o'clock" was used for SEM analysis, and one test result showed up no traces of lead in the solder on its backside. The consequence of the total coming apart was that it was possible to treat the individual parts one by one and thus achieve as uniform a final appearance of the fibula as is the case. The Article in full, also containing the Conservation on two other Magnificent fibulae, can be read in "Meddelelser om Konservering" 2002 vol. 2 page 18 - 27. Note 1: Archaeologist in charge was Linda Boye. Further reading on the cemetery in "Høje-Taastrup før buerne", published by The County of Copenhagen Museum Council in collaboration with the Høje-Taastrup Local Council, 1999. Note 2: The fibulae were found in graves No. 4, No. 12 and No.18. Note 3: Fixation and X-ray photography by Conservator Anette Adomat. Note 4: Later calculations showed that the swastika fibula originally consisted of 159 component parts. Not all were recovered, but still 130 parts were found, as some of the original components were now broken up into fragments. Photos No. 2 and No. 4 by Jesper Weng. AcknowledgementsSincere thanks to the Roads Directorate, who met the request of the Museum Council for a grant of DKK 252,800.00 for the conservation of the three magnificent fibulae. The work could not have been done so carefully without the great interest and support of so many people right from the beginning and all the way through till this point. Special thanks to Head County Archaeologist Ditlev Mahler and County Archaeologist Linda Boye. Also to Helge Brinch Madsen for proof-reading; Nicoline Kalsbeek for SEM analyses; Anette Adomat for fruitful collaboration; Ole Christensen for this English version; E. Benner Larsen for his invaluable expertise and invigorating enthusiasm, and finally to Frank Winther of the firm of Larsen & Shiøtz for the manufacture of the two very fine storage and display cases designed by E. Benner Larsen. |
Allowing for the distance between the fibula and the X-ray film E. Benner Larsen - solely on the basis of the X-ray photos - worked out a very precise drawing of the base plate of the fibula. This drawing was photocopied in such a way that on the same A4 sheet of paper there was a positive as well as a negative, i.e. a reverse, drawing of the base plate.
The spokes of the fibula were numbered 1-4, the flat rosettes 1-12 (like the face of a clock); the four hemi-spherical rosettes (at the end of each spoke) were numbered with half-hour numbers, and the four small intermediate rosettes (between the spokes and the center rosette) were named with the four compass directions. The individual rosettes were further sub-divided in the same way as the face of a clock. All the rosettes are ringed with silver wire, extremely skilfully manufactured to resemble miniature strings of beads, and at the center of each a rivet is mounted. The drawing was an excellent working tool, as the individual component parts could be turned over whenever needed. This facilitated their exact placing. (Note 4)