Restoration Report

Copyright © 1996–2012 CBH

on the
Rädecker & Lunau Square Pianoforte c1832
owned by Hong Kong University Music Department

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Rädecker & Lunau Square Pianoforte c1832 water damaged case 70K jpeg
Water damaged case of the Rädecker & Lunau Square Pianoforte
Asia map: Hong Kong 12K jpeg

The instrument was found with serious and extensive water damage from a typhoon-filled airconditioning duct in room 123 of the HKU Main Building. The left case side had separated from the spine and the lid prop jammed in the resulting gap. The left wrestplank block had separated from the case side. The finish on the fallboard veneer, nameboard and case front rail had disintegrated, the various veneers water damaged and the brass inlay disjointed. The soundboard had seriously deflected and split in several places. The front soundboard apron had become unstuck. The extreme treble bridge had split and almost completely separated from the soundboard. Many of the wound bass strings had seriously corroded between the windings and most other strings showed signs of rust at least around the hitchpins. The action showed some signs of water damage with the leather hammer coverings discolored and some of them separating from their respective hammer heads. The original keyboard, which was in exceptionally good condition, had particularly suffered with the water pooled there for a considerable time. All the original ivory keycovers, ebony sharps, and wooden keyfront mouldings had become unstuck. All the keylevers had discolored and many of them had warped. Some of the joins of the keyplank flitches had separated. Various mouldy growths were attacking the inside of the instrument. Stabilization work was undertaken on site shortly after the damage was noted, and preparations made to prepare and pack the instrument for subsequent workshop restoration.

Enable the instrument to play once again, preserving as much of the original material and character as possible.

All veneers were able to be saved including the very badly cracked ones on the fallboard exterior. To accomplish this, many of the case veneers were steamed and reglued, and the case stripped, bleached, shellacked and waxed to ensure uniformity of appearance. The nameboard was badly warped and split and had its brass inlay damaged: Its veneer was removed and refixed after the body was reglued and sanded flat.

The lid exterior was stripped and very lightly bleached as necessary to match the case. The original finish remains on the lid interior. Cracks in the case bottom were filled with gapfilling marine glue. The missing left case interior corner block was replaced. The gold painted finish on the wrestplank—probably dating from the c1960 restoration in Denmark when it was considered necessary to hide the wrestplank veneer cracks—was removed, and the veneer repolished. The warped soundboard was flattened without removing it from the case and the cracks shimmed or glued as necessary before its surrounding thin mouldings which had floated off were reaffixed. The bass end of the bridge had rolled over somewhat to the right with the excessive string tension prior to the incident. It was stabilized and the gap filled with a flexible water based glue. The additional bridge had lifted from the soundboard so it was reattached. A broken leg top screw was retrieved from the case, rebored and attached to its leg. Adjustments were made to the leg heights after restringing to bring the legs into correct profile alignment and level the case. The kneelever fulcrum which was not original and merely a tack-on repair, was discarded and a new one made in mahogany to fit in the exact place of the original softwood one and ensure correct operation of the damper lifter. New stainless steel hinge pins were made for the lid, and the fallboard hinges were moved to enable it to close in correct alignment to the case.

Rädecker & Lunau Square Pianoforte c1832 keyframe 58K jpeg
Keys being relaid on the keyframe

Most of the water pooling occurred over the key front area, extensively damaging the keyboard and requiring much work to return it to usable condition. All the ivory heads and tails, the ebony accidentals, and the maple front mouldings were detached. On site, these loose pieces were carefully bagged and labeled to ensure their subsequent return to the correct key levers. The keys themselves which were discolored by black sooty mould and a green fungus, and were washed in antiseptic solution to prevent further decay prior to the full restoration.

After the instrument reached the workshop, the two keyframes which were in pieces were reglued. The cloths believed to be original were unable to be reused because of shrinkage, so original style woven cloth was chosen for its replacement of the backrail, frontrail cloths. New balance punchings were made from appropriate material.

Rädecker & Lunau Square Pianoforte c1832 restored keyboard 55K jpeg
Ebony & ivory keycovers, and keyfront mouldings reattached

Several keys had split or severely warped. The splits were repaired, and the warped keys corrected by wedging where necessary. The frontrail, which was slightly bowed prior to the incident, bent so far towards the back of the instrument to make the keyboard completely inoperative. Rather than sacrificing the keyboard alignment this important part offers, it was decided to extend the front mortises under every mainframe keyhead to allow them to work on the frame in this new warped frontrail position. The keylevers were then leveled and spaced prior to the covers being reglued.

The ivories which had curled were flatted by moistening with warm water and pressing. All keycovers were glued while the keys remained on the frame, using a technique somewhat similar to when the keyboard was originally made. The keyheads were first glued, followed by the tails, the front mouldings and the accidentals. The ivories were selectively lightly bleached to reduce the water staining where necessary. The mouldings were sanded flush with the key sides and their fronts varnished. The ivories and ebonies were buffed. The keydip was adjusted by card shims under the heads after the action work was completed. The rear of the bass accidentals were trimmed to clear the nameboard in the new main keyframe position. A new cloth strip was glued under the nameboard.

Rädecker & Lunau Square Pianoforte c1832 stringing complete 80K jpeg
Stringing complete and dampers installed

The strings existing at the time of the incident were modern steel, and along with the tuning pins, probably dating from the 1960s restoration. Opportunity was taken to use historic profile tuning pins with rectangular heads similar to what would have been found in this instrument when new so the existing unusual-sized pins were discarded. The wrestplank holes were cleaned and redrilled to enable the new pins to be fitted. Because the existing modern strings gave an inappropriately high tension throughout the instrument, distorting the case and effectively preventing a musical use anywhere near modern pitch, measurements were made of the instrument prior to case repair enabling a new stringing schedule to be determined by computer, with reference to schedules of original stringing from similar surviving instruments of the early nineteenth-century. This resulted in a more even spread of tension at the calculated pitch of A425, totaling 2429kg, a reduction of 36% from the 1960s stringing.

The instrument was restrung with historic style soft iron wire, lightly tinned to help delay future rusting, along with yellow and red brass in the tenor and bass. For the bottom ten notes, custom made openspun strings were used with yellow brass cores and copper overwindings. Spare plain strings and schedule for future odd replacements were provided, along with a custom made tuning hammer for exact tuning pin fit and A425 tuning fork. The graph below shows the single choir tensions, and full stringing data is available in a pdf file.
pdf icon 2K png String tension chart 33K jpeg

Rädecker & Lunau Square Pianoforte c1832 action 60K jpeg
Aligning the damper lifters with the keytails

The English Square action with grasshopper escapement required extensive rebuilding. The various action parts which had become detached from their keys were repaired where necessary and reattached. Several brass hopper springs were made and fitted to those that were badly damaged. Water had pooled in the area of the damper lifter assembly at the back of the instrument interior. As a result, all the leather hinges of the damper lifters and the mahogany damper screw blocks were unusable. While the hammer coverings escaped almost unscathed, the excessive moisture had affected most of the old leather hinges. These were found to be in very bad condition and far too fragile for the instrument to be reassembled and played with any degree of reliability. Accordingly, the hammer shank hinges on the main frame were replaced with Nigerian chieftain goat skin, the underhammer and damper lifter hinges with kangaroo skin, and the broken or damaged grasshopper hinges replaced with parchment. The mahogany damper screw block hinges had hardened and cracked, so these were replaced with kangaroo also. The dollypeg damper cloths remain original. Any detached hammer coverings were reaffixed, and replacement coverings made for the very top note. The hammer heads of the main frame were cleaned and lightly sanded to improve shape.

Rädecker & Lunau Square Pianoforte c1832 restoration complete 40K jpeg
The finished instrument

The instrument was tuned several times until the strings held pitch. The keyframe positions were juggled for optimum alignment and then fastened through the balance rails with the original screws. A multitude of action adjustments were made to the instrument after some playing in. Following an informal opening concert, it was carefully packed in a protective padded cover, and the crate it arrived in was cut down to an appropriate size for its return journey by air to Hong Kong. The restoration was judged very successful, with this rare Continental instrument once again able to be played on demand, and with good tuning stability. The tone is fine, and the touch quite typical of good instruments of the period.

Nameboard 23K jpeg


With thanks to the creative input of
     Eddie Valk, Norm Neilson, Barry Nottingham, Lou Parke,
     Howard Pollard, Ron Sharp, Catriona Turnbull & Jamie Rowe.

Carey Beebe
May 21 1996

FOOTNOTE July 2012: Dr Ibo Ortgies of Göteborg Organ Art Center (GOArt) obtained a similar instrument in excellent condition by Rädecker & Lunau in Sweden in late 2011. In correspondence with me, he mentioned research by Ulrich Althöfer revealing that the firm was established in 1831/32, effectively establishing the earliest possible date for instruments with this signature. My original estimate of c1830 for the Hong Kong was not too far off: Most museums and collectors show a tendency to assign construction of undated instruments to earlier times. One European collection had a Rädecker & Lunau square with a metal plate and much later action type, yet it was dated “c1820” in their publications, and an expert engaged by the previous owner of Dr Ortgies’ own instrument provided an impossible date of “c1805”.

The ongoing research of Dr Ortgies relating to his piano, including many excellent photographs and references to other surviving instruments by Rädecker & Lunau, can be found here.

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