A Secret-Hiding Iron Chest From Pärnu Museum
Authors: Grete Nilp, Ingrid Pihelgas, Helmut Välja
Number: Anno 2022/2024
Category: Conservation
When arriving at Kanut, the iron chest from the Pärnu Museum was impressive in form and weight but dirty and rusty on the surface. The powerful locking system and the obviously handmade look of the item immediately signalled that it is much older than originally thought and that the dirt and corrosion layer hides colourful secrets underneath it. (Reference 1)⁽¹⁾
A closer look at the chest made it clear that the knowledge and skills of both metal and polychrome conservators will be needed here. To begin, a thorough investigation of the item was carried out, trying to understand where had it come from and what had happened to it over time. Most likely, the chest had once fallen victim to looting – the lid had been twisted and broken open with levers, which is why it had also been stored separately from the main body of the chest in the museum. [ill 1] Someone had probably been very interested in the contents of the one-time safe box, and having no key, they had tried to access what was hidden inside by brute force. On the underside of the lid there was a sophisticated locking system designed to securely protect what was stored in the chest. As the chest had been broken open, some of the attachment rivets had been pulled open and got lost in the process. Another missing detail was the plate covering the locking system usually found on such chests, on which the name of the master or workshop may have once been inscribed. [ill 2]
Each detail of the chest was individually forged, and the iron bars of the locking system were each slightly different in thickness. The fact that no detail was perfectly accurate suggests that the item as a whole was handmade before the Industrial Revolution. The chest does certainly not contain any industrially manufactured elements.
How did the lock system work?
Looking at the chest from the outside, a large decorative lock hole can be seen on the front. Upon closer examination, it turns out that this is just a decoy, intended only for deception and trickery, as it has no real purpose. [ill 4] The actual lock hole is located in the middle of the casket lid and is covered with a cover plate. However, to lift the cover plate and gain access to the lock hole, you have to know the exact right spot that will make the plate jump up when moved – there is a special fastener for that slightly below the cover plate. [ill 5] [ill 20] [ill 21] Only then can you insert the key into the lock hole and set in motion the seven fixing devices that hold the lid. In addition to these, there are three more stationary fixing devices in the clamping mechanism. Thus, when the coffin was broken open, all ten fasteners had to be broken at once, which made it very difficult.
On the front of the coffin there were also lugs for hanging locks as an additional security measure. [ill 3] Markings on the inside of the chest indicate that originally a small, lockable box for smaller valuables has been located there. [ill 6] Unfortunately, it has been lost over time. The strong lock with a multi-stage system was meant to protect the owner's property in the best possible way.
What did the item originally look like?
The appearance of the massive iron chest seemed to hide something exciting – under the dirt and rust, there were numerous references to a versatile and colourful polychrome which definitely required closer examination. It turned out that on the sides of the chest there was a wonderfully well-preserved original painting with a floral ornament depicting very different types of stylized blossoms. [ill 10]
Conservation
The first to start working on the chest was the metal conservator Helmut Välja. For a better and more complete preservation of the chest, it was decided to attach the lid back to the item. [ill 9] Some of the mounting bolts of the hinges were missing, so new ones had to be made on the lathe. As a result of breaking open, some of the fixator loops were curved outwards, and the lid itself was twisted. As a result of gentle but consistent bending, they were bent backwards using levers and clamp screws – the approach had to be careful, and due to the abundance of polychrome that had been preserved, heat could definitely not be used.
Then the metal conservator could start working on surfaces that did not have paintings – the locking system, the inside and the bottom of the chest. [ill 7] The rusty and dirty locking mechanism was mechanically cleaned and rust was also mechanically removed from the most severely damaged part, the bottom. [ill 8] At its time, the locking system was probably lubricated with some kind of lubricant for better movement, but no traces of it had survived. However, the metal had been preserved very well despite the rust and the dirt. A thin protective layer was applied to the surfaces. (Reference 2)⁽²⁾ [ill 15] [ill 16] [ill 17] [ill 18] [ill 19] Since the chest lacked a key, a new question arose after fixing the lid – how to prevent the lid from locking itself? After discussion, it was decided to opt for a permanent, yet reversible and unobtrusive solution, i.e. the main beam moving the locking system's fixators was blocked with tiny thin metal wedges. The wedges can be removed and they do not cause tensions in the system, but they won't let the lid lock.
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Then, polychromy conservator Ingrid Pihelgas took over and started working meticulously on the colourful paintings on the sides of the chest. At first sight, the surface was strongly tarnished and soiled, and had probably been conserved before, which had included covering with a protective layer, possibly wax.
The work started with a general wet cleaning of the surfaces. (Reference 3)⁽³⁾ Then, cleaning tests were started to determine the most appropriate method for removing the darkened cover layers. (Reference 4)⁽⁴⁾ Cleaning gel was applied to the surface and left there for up to 45 minutes, depending on the thickness and sensitivity of the layers. Then the gel was removed and after a while, post-cleanup was carried out using ethanol. [ill 11] As the delicate floral ornament was painted slightly protruding from the surface, mechanical aid with a scalpel was needed at some places. Fixating the colours was carried out in parallel to the cleaning process. (Reference 5)⁽⁵⁾
Shiny, delicate blossoms and a bright green background painting emerged in the course of the cleaning, forming a beautiful contrast to the robust form of the item. For the final touch, the paintings and the outer surface of the chest were covered with a protective lacquer. (Reference 6)⁽⁶⁾ [ill 12] [ill 13] [ill 14]
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All in all, this rusty and initially "boring" item turned out to be a versatile and fascinating challenge offering various surprises to the conservators. (Reference 7)⁽⁷⁾ [ill 22] [ill 23]
References
As the appearance of the chest gave reason to believe that the item could be much older than presently noted in the MUIS system (19th century), specialists from the Tallinn City Museum were consulted to estimate the possible manufacturing date more accurately. Metal conservator Jaan Märss and curator Kristiina Hiiesalu commented: “The chest could conceivably have been made around 1750 - 1775. The type of the spring rules out an earlier date (the 17th century) while e.g. the rough rivets are still individually handicrafted items. 19th century rivets would be more uniformly mass-produced. The tiny flowers on the paintings match rococo-style floral ornaments and the plate of the false lock is suitably asymmetric.
Similar chests were produced in various sizes en masse in Nürnberg from late 16th century to the third quarter of 18th century. After that, classicism started to take over. 19th century neo-style would have used cheaper mass-produced solutions (e.g. round-headed rivets).” ↩︎5% tannine ethanol solution ↩︎
5% triammonium citrate water solution ↩︎
The best solution for cleaning turned out to be the following gel: Carbopol EZ2, Ethomen C-25, acetone, benzyl alcohol ↩︎
20% Paraloid B-72: acetone, xylene in a volume ratio of 1:2:2 ↩︎
10% Paraloid B-72 in ethyl acetate ↩︎
Object of the Pärnu Museum, PäMu_26681Aj366. Kanut’s conservation passport No 2024:0043 in MuIS. ↩︎