I am describing a bone casket decorated with engraving and gold foil, the beauty and exciting conservation process of which are worth sharing with you. As objects made of bone have been quite rare on my worktable up to now, this item was a provoking challenge.
In addition to some experience with substances like gypsum, ceramics, glass, marble and plastics I was in need of more information and know-how about bone. The problem of restoring the visual entity of the casket became essential – it had to be resolved whether either to replace the damaged details with natural bone material, to find the best plastic imitating bone or just leave the losses untouched.
About bone as a substance in general
Bone is a hard substance of animal origin, that is bones, antlers, sheds, hooves and teeth, the elephant, mammoth and walrus’s tusks included. It can be proceeded to make various objects.
Attitudes to animals and hunting have considerably changed in time. An international convention has been concluded to curb the extinction of endangered animals and plants – the CITES, i.e. Convention on International Trade in Endangered Species of Wild Fauna and Flora. An agreement that all trading with ivory in all the states that had joined the convention was to be prohibeted was reached at a conference in Switzerland in October 1989, since poaching had already endangered the whole elephant population.
Ivory vs. plastics
Ivory has been the most valuable bone substance throughout the centuries. It is luxurious, beautiful, durable and quite easily tractable.
Demand for ivory started growing in the late 19th century. It was not most needed for making artefacts or objects for religious services any more but basically for producing bowling balls and piano keys.
This, in its turn, encouraged inventing synthetic materials. The breakthrough for raw material made on the basis of nitro-cellulose began in 1862 when Alexander Parkes (1813-1890), a British inventor and master in metalwork introduced synthetic ivory at the London World Exhibition. This very first artificial material (polysynthetic thermoplastic) named Parkesine in honour of its inventor was cellulose worked with nitric and sulphuric acids. Another artificial material was launched next year, in 1863. One of the biggest billiards-makers in the USA was looking for someone who could replace expensive ivory for making billiard-balls with some other material. Their newspaper advertising made brothers John Wesley (1837-1020) and Isaiah Hyatt invent a method of coating a tightly wadded paper- and shellac-ball with a thick layer of colloid solution. The brothers called their synthetic ivory Celluloid. The billiard-ball invented by the brothers was in production in the USA already in 1868.
The Hyatts invented the new material for the purpose to imitate ivory and the result was indeed quite similar to the true substance. They imitated even the Schreger lines, so characteristic to bone. To achieve that they had to press several sheets of Celluloid with different transparency tightly together and when these sheets were cut afterwards they showed the expected lines. The new material suited well for objects that had earlier been made of ivory like caskets, boxes, jewellery, articles of toiletry etc. Thanks to the invention of new synthetic materials in the 20th century bone was not so much in demand and objects made of it did not spread so widely any more.
Traditional Russian engraving
Bone objects are rather scarce in Estonian museums’ collections. One reason for that might be that the local settlements were small and professional artisans working with bone were few even in bigger localities. Nobody passed the true skills to the following generations. No market for bone objects evolved either. Bone was evidently used only in households for making simpler tools and commodities.
In Russian folk handicrafts, however, bone engraving is one of the most outstanding branches of manual crafts. The two leading Russian centres of bone engraving were Archangel and Tobolsk.
The Kholmogory masters of the 18th and 19th centuries made a lot of traditional folk-art objects like chess-pieces, icons, furniture, snuff-boxes, baskets, lockets, combs, women’s toiletry items and other things. As so many objects were made of the same material each one had to be made distinguished and unique. So a great part of the bone objects have been decorated with deep (about 1mm) carved, grooved, engraved or sawed ornaments. Traditional plant motifs were engraved on the caskets but also lacy patterns consisting of small concentric rings with a dot-eye in the centre were popular. Hence the term eye ornament. Such bone caskets can be seen in several Russian museums.
The casket of the Narva Museum
The casket described in the present article belongs to the collection of the Narva Museum.
Sergei Lavrov bequeathed his art collection and his house to the town of Narva. The Narva Town Museum was established after Glafira’s death in 1913. There had been a museum in Narva already earlier, though. In 1726 Catharine I had bought the house in which Peter I had stayed. This museum did not collect only objects connected with the tsar but other items connected with the town’s history as well. In 1934 Peter’s house-museum was affiliated to the Lavrentsovs Museum (the present Narva Museum).
Three paper labels and some markings written on wood on the bottom of the bone casket show when the object was registered at different times in the Lavrentsovs Town Museum and/or the Narva Museum (signs: T. I/XXV/N#; KN/1438; NM 652; 2x NLM 1/Aj1: 51; 817). [fig 8]
Description of the casket
The museum has registered the dating from 1800-1850. It is a wood casket with a lid, 11.5 x 15.8 x 23.5cm in size, decorated with bone plates. [fig 5] These bone plates are ornamented with engravings and openwork flower ornaments that give the casket a rather lacy look. The fossae (grooves) in the plant ornament have been shaded green. The backing for the openwork surfaces is gold foil that is visible through the bone lace. The bone plates have been fixed with small nails and glue. The front part has a copper working lock together with a key, but the lid has no fastening on it.
The box part is supported with four wooden legs propped up with a small piece of wood at the back. The legs have been glued on. Their outer sides have been covered with bone plates. The sides of two legs have been painted light, obviously to imitate bone that is missing there. The bottom of the casket is made of solid wood but its sides and lid are made of plywood. The lid is hollow inside and its interlay is of plywood plate.
The plywood used for the casket may hint at the later period of its making than the time the museum has given. It may also be a later-day reconstruction of the casket. In this case the initial bone details have been glued onto the plywood casket. The bone casket might have been made in the late 19th or even the early 20th century, when the masters still used traditional patterns and methods, but might have been using more modern materials instead of solid wood. As it is obviously the work of a Russian master who obtained his material from the vicinity, the plywood may come from local sources. It is known that the Luther Plywood Factory had a branch in Narva at the end of the 19th century and this branch had its own shop in St Petersburg (1897).
The later repairs can be seen in added details, traces of gluing and repainting.
The aim of the conservation was to restore the entity and disposability of the museum piece, retaining its originality and its beautiful looks.
Owing to the missing details the surface of the casket was uneven and looked unsteady. Its construction had become loose and the lid did not connect with the hinges. Some details on the bone plates were missing and the lacy pattern was broken here and there. Four bigger bone plates and five details of the bone lace had become loose. [fig 6], [fig 7]
It was decided to reconstruct the missing parts after some deliberation, though. The right material for that seemed to be only something true to its time, that is natural bone and glues that had been recognised as suitable for conservation and would match the bone. The existing loose details had to be fixed and new details had to be made to replace the missing ones. The missing parts of the foil were not filled.
Cleaning the surface
Both the interior and exterior surfaces of the casket were carefully cleaned using a vacuum cleaner with its finest nozzle and a soft brush. [fig 9]
The surface was badly soiled and thus wet-cleaning was needed as well. First of all tests with ethanol, saliva and 2% tri-ammonium citrate aqueous solution were carried out. Saliva was chosen for general cleansing
Metal details were cleaned with a glass-fibre pencil and steel wool 0000.
Tidying up the bone plates
Some of the bone plates were loose at the ends and needed fixing up. The old plates were glued with PVA glue. The four loose old plates and the five tiny details of the bone lace were set at their initial places. Pellet-bags and clamps were used for pressing. [fig 11], [fig 14], [fig 15]
A box full of old ivory piano keys had been brought to the Kanut for reusing and the keys were good for making new details to replace the missing ones. These keys actually helped to make the decision about adding new details – usually such a decision is not made when museum pieces are conserved.
The details were jigsawed into right size and their edges were honed with sandpaper. Then the surfaces were polished with nail polish (4000) and a woollen rag. Decorative engravings were not made in order to leave the new parts visible. All in all thirteen new details were made. [fig 12] Three or four dots of PVA glue were dropped under every bone plate to grant an easy removal of them if it became necessary. [fig 13]
The wood of the casket began to shrink and the brittle old glue slackened in our dry workroom (30% humidity). That made us re glue two loosened legs.[fig 16] The loose interior plate had evidently also suffered due to the dryness and so the interlay had to be removed. In the course of this work an idea to leave something for the would-be conservators to discover was realised in writing a dated letter about the conservation process, the name of the conservator and the establishment were included. [fig 17]
The letter written in graphite pencil was fixed on the bottom of the lid with a couple of paste dots in the corners. [fig 18]
In this article I have attempted to share all the beauty and pain connected with a bone object with the reader. Thanks to the sources I myself got answers to my questions about the history of bone artefacts, the possible origin and dating of the casket, the material and methods used when making it. The bibliography I used showed me how little has been done in Estonia in studying bone as a substance and especially its conservation.
It was a really lucky chance that this box full of old ivory piano-keys had been brought to the Kanut. So it was possible to use natural bone – reusing is wonderful for restoration and conservation.
For summing up I can say that I gained an experience worth having and I can affirm that I did my best to give the lacy bone casket its distinguished looks back, granting its longevity for the museum visitors to enjoy. [fig 19], [fig 20], [fig 21], [fig 22], [fig 23]
Two caskets belonging to the Narva Museum were conserved at the Kanut in 2018. In addition to the casket described in the article above, another wood casket with bone ornaments was spruced up (NLM 1:52Aj. MuISi code 2310226, conservator Jolana Laidma). [fig 1], [fig 2]