Restaurierung Rönsch

Description, sociology and dating

The clock can be assigned to the group of Kommodenuhren – clocks that were meant to be placed on top of a chest of drawers. It is designed as a half-pavilion with columns that is closed on the back. The pavilion has two free standing columns, two other ones on the back panel are shaped as semicolumns. The columns are a variety of the Doric type although having a base that is, like the capital, realised as a collar made from brass. Three steps lead inside the pavilion the floor of which is inlaid with a chequered pattern. The back panel carries a mirror. The roof of the pavilion is designed similar to a pagoda roof, just without the top. The frieze underneath the roof is decorated with a meander ornament in contrasting marquetery. The round clock case is fixed on the roof. It is crowned by a symmetric ornament after the manner of classic antiquity, combining floral elements and swans, evolving around a central torch ornament. The round clock face is enamelled in white and bears black Arabic ciphers. The hour hand is designed in the form of fleur-de-lys, the minute hand as a modified, angular Breguets-form.  

The design of the ornamental crown as well as the materials used – mahogany and black lacquer – suggest that the clock was made in the first quarter of the 19th century, in the epoch of empire. Similar objects can be found mainly in the Austro-Hungarian empire. There is for example one piece from Austria from 1800/30 (Hüttler, P. (n.d). Empire Kommodenuhr www.fahrzeuge.dorotheum.com) that is designed as a semi pavilion, too. Another clock from Vienna from the first quarter of the 19th century (Kohlhammer-Duschek, B.; Scheed, C. (1997). Verkaufskatalog Firma DS. Antike Wiener Uhren. Verkaufsausstellung. Wien, „Museum, in dem man kaufen kann“/ D&S 12.09. – 25.10.1997. Wien: D&S. p. 91.) is similar in design and materials, but the decoration is by far more splendid and sumptuous. Both objects are decorated with swans, too, yet neither of them carries them prominently in the crown. Judging by the materials and the way the elements are made in detail the clock has to be subsumed to the bourgeois area. The wood works were carried out exquisitely while the cast and gilded bronzes seem a bit crude. All in all the clock is  decorated less preciously than a courtly object would be.

Construction and surface

The base of the pavilion consists of one filled and two non-filled semi-circles that are butt joined and glued together. The roof is made from two pieces of which the upper one is turned and glued to the lower piece. The floor respectively the roof are connected to the back panel by an overlap joint, which was subsequently fixed with nails. The free-standing columns are held by a nail run through the roof on the top and a screw on the bottom. This mounting is likely to be a later rework, assuming that the columns originally were simply glued to the roof and the bottom. The mirror rests in a rabbet in the roof and is additionally held by the back panel that is fixed with four nails. The clock case is affixed to the roof with two threaded rods and screw nuts.

All visible wooden surfaces are coated with a clear lacquer of homogenous shine. Yet large areas are streaky and blistered. In smaller areas a matte layer covers the lacquer. The pagoda roof is highly polished with black lacquer. A patchy, matte and brownish lacquer covers the surface of the clock case. All untreated wooden surfaces on the back of the clock are stained dark brown. 

Damage and reworking  

The overall state of conservation of the clock was relatively good.

The majority of the damages were caused by keeping the clock in adverse climatic conditions causing the wood to warp. Those damages were partially worsened by improper reworking.

The warped roof led to the fixing of the columns with nails through the veneer of the roof, leaving the columns still being loose, the holes being filled in with wax putty not matching the colour of the wood. The same putty was used to elongate the free-standing column on the right to fill in the gap resulting from the warped roof. The streaky lacquer was likely to be a rework, too, as were the matte areas on the surface of the lacquered wood that presumably were some kind of furniture polish and the patchy, matte coating of the clock case that seemed to be some kind of patination. Both affected the overall appearance of the clock. The mirror seemed to be rather a later addition than the original one as well due to its making and the rough, unpolished edges.

There was a loose joint on the back panel and some of the veneer was loose as well. On the steps there were two pieces of veneer missing. The left tip of the crowning ornament was broken off and missing. The whole object was standing quite crookedly because some of the felt pads were missing. The clockwork was out of order.

Scientific examination

The types of wood used for construction as well as the one used as veneer were determined in order to make suitable wood replacements. The base wood used is pinewood (Pinus sylvestris), the free-standing columns are made of oak wood (Quercus robur), the semicolumns of mahogany wood (Swietenia sp.), the turned part of the roof from alder wood (Alnus sp.). Whilst these types of wood were determined microscopically the types of wood of the veneer could only be determined macroscopically due to the impossibility of taking sufficient samples without causing damage. The types of wood used for the frieze and the chequered pattern are mahogany (Swietenia sp.) and boxwood (Buxus sempervirens) as well as baked acer (Acer sp.) or pear (Pyrus comunis). All other veneers are palisander wood (Dalbergia sp.).

Various methods of analysing the surface verified the assumption that the lacquered surface was heavily reworked. The examination of the surface with ultraviolet light (The ultraviolet lamp used: UVAHAND 250 GS Fa. Hönle, uv-technology, Gräfeling/München) showed a blueish-greenish, milky fluorescence on the lacquered areas that is typical of synthetic resins. In the matte areas the fluorescence was diminished. The retouches around the two missing veneers were clearly visible. The metal applications mainly had no fluorescence. In some areas an orange fluorescence that is typical of natural resins showed underneath the streaky fluorescence of the synthetic resin. As a reaction to this finding cross-section samples of the surface were analysed microscopically in order to find out if there are older and potentially original layers of lacquer lying underneath the current surface. The sample showed two transparent layers of blue-green fluorescence topped by another transparent layer without fluorescence. That means that the sample showed two layers of rework as well as one assumed to be a furniture polish. It showed, however, no trace of an underlying lacquer based on natural resins which leaded to the assumption that the sample was taken at a point where nothing of this layer was left. The analysis of a cross-section sample of the pagoda roof showed a multi-layered structure consisting of a tinted ground layer and multiple transparent layers of lacquer. On top of the last transparent layer lay another tinted layer that was coated by a transparent layer showing the same blue-green fluorescence as the other one. All lacquered surfaces were thus reworked in one run. Next the tests regarding the solubility of the lacquer were done to find a solvent that could be used to take off the matte polish without harming the lacquer that was intended to be kept. The result was that the polish could be removed with aqua dist. in most areas, some spots required working with white spirit (100-140 °C), both of which did not interfere with the solubility of the lacquer. The patination coating the clock case consisted of two layers of which the top one could be removed with white spirit (100-140 °C), the bottom one with ethanol.

Restoration

The aim of the restoration was to re-establish an overall harmonious appearance of the clock. Here the main focus was laid on restoring the polluted, partially streaky and matte surface that should be given an even finish. The restoration of the surface of the clock case turned out to be much more complex than assumed at first due to the fact that the patchy appearance was not only caused by the poorly made patination but also by the uneven oxidation of the metal.

The first steps to be taken concerned the constructional work. The loose free-standing columns were removed, the drill holes were filled in with limewood. On the top end a wooden peg was inserted that fits a drill hole in the roof. The effect of the warped roof was diminished to a certain extent by taking the following steps: The entire half pavilion was disassembled, the residues of glue on the joints were thoroughly removed as was an interleaved small plate on the left free-standing columns and the wood putty on the right free-standing column. Then the pavilion was reassembled by gluing the joints and fixing the columns with glue on the top and screws on the bottom end. That way a slight tilting of the roof was possible.

Next up was the restoration of losses in the veneer. The missing veneer on the steps was replaced with palisander that was bleached with ethanol (soaked for four months), adjusted colour-wise with water-based wood stain (Körnerbeize by Kremer Pigmente) and then French polished, making sure to have a sufficiently thick layer of orange shellac (by Kremer Pigmente) before the first sanding to omit damaging the stain. The veneer was then fitted and glued, retouching the edges with watercolours (by Schmincke). Loose veneers were glued down, for some areas a custom-made softening block had to be used. The holes in the veneer of the roof left by the nails to fix the columns was filled in with wood putty (Stucco Kitt by Signorello) that was tinted with pigments and retouched with water colour applying various in-between layers of bleached, dewaxed shellac (by Kremer Pigmente). All bonding was done with hide glue (skin and bone 1:1)

All that being done the lacquered surface was the next thing to fix. The whole surface was cleaned with aqua dist., at the same time removing some of the matte furniture polish. The remains of the polish were removed with white spirit (100-140 °C). The streaky, partially blistered lacquer was burnished with abrasive linen (Micromesh, grain 4000-12000, by CS Cybernetic-Systems GmbH). The matte layer on the clock case was removed with white spirit (100-140°), the underlying tinted lacquer was taken off with ethanol (partially prepared as gel). The patchy layer of oxidation products was removed using EDTA (77g of ammonium acetate in 200 ml of water, 350ml of 25 % ammonia solution, 450 ml water, used as a 0.1 molar solution in water) subsequently cleaning under running water and dehydrating with a rubber soaked with ethanol. The clock case was then airbrushed with Paraloid B72 (10%, by Kremer Pigmente). All other metal surfaces were cleaned with ethanol. The missing tip of the crowning ornament was replaced with a cast in brass taken from the intact tip on the other side. The replica was fixed using laser welding. To make the replica blend in with the rest of the ornament its surface was retouched with tinted Paraloid B72. The clockwork was repaired by a horologist.