Art Conservation for the Classical Masks at Sonobudoyo Museum, Yogyakarta

Sonobudoyo Museum Yogyakarta is the complete museum after the National Museum in Jakarta. There are many art collections in the museum, including bronze statues, gold statues, various ceramics, leather puppets, batik, bamboo works of art, furniture, and various Indonesian mask characters. The masks are treated and displayed in a particular place so that they can last hundreds of years and be seen until now. The research was aimed at how art conservation was carried out for these masks and at a particular strategy in maintaining, protecting, and caring for them. Therefore, it is interesting to study and understand the art of conservation for classical masks at the Sonobudoyo Museum, Yogyakarta. The research results showed that the knowledge of caring for, maintaining, protecting the masks as objects of art collections and cultural products with aesthetic, artistic, and historical values can still be known by the public and the generations. Moreover, the art conservation is also essential to know, not only by conservators but also by the broader community, to preserve and develop classical masks in the archipelago.


Art Conservation for the Classical Masks at Sonobudoyo Museum, Yogyakarta
Introduction Sonobudoyo Yogyakarta State Museum has a long history, from once a colonial museum to a state museum. Sonobudoyo Museum was founded on November 6 th , 1935, by Java-Institut, a cultural research institute founded on August 4 th , 1919. This institute aimed to transcribe Nusantara (indigenous) culture covering Java, Madura, Bali, and Lombok. Most of the collections in the museum come from Java-Institut grants, which until now are dominated by artifacts from the four cultural areas.
The establishment of Sonobudoyo Museum was decided during Java-Institut Cultural Congress in 1924 in Yogyakarta. Data on handicrafts and art objects were collected through the Crafts Office (Nijverheid Kantoor) in Java, Madura, Bali, and Lombok during the congress. The results of the collection of cultural data were documented in the form of the book entitled De Inheensehe Nijverheid op Java, Madura, Bali, en Lombok, whose materials are used as the top collections of the museum (Priyanggono, 2018: 23-36) and now are added from various donations of unique collectibles.
Sonobudoyo Museum is the secondcomplete museum after National Museum in Jakarta. Sonobudoyo Museum contains Nusantara historical collections, works of art, and cultures. The collections include Neolithic ceramics, bronze statues, statues of gold, shadow puppets, ancient weapons, various types of batik, various works of art made of bamboo, and various Javanese and Balinese mask characters.
Many collections are arranged and exhibited inside the museum room and on the outside of Sonobudoyo Museum. The collection outside the museum building consists of objects made of relatively weather-resistant materials such as temples, statues -including those made of stones -and other temple decorations. These objects were obtained from the time of Hindu-Buddhist kingdoms around Central Java and East Java. Collections in the museum room are made of materials that are very susceptible to weather, pollution, dust, and other impurities. These collections use a type of window display and are equipped with spotlights to make them more attractive when visitors are coming to the museum. The collections are also supported by room humidity regulated based on the temperature in each exhibition room. Collections displayed in the room include various glass paintings, puppets, bronze statues, gold sculptures, wooden handicrafts, building art and furniture, batik, woven products, and classical Javanese and Balinese masks.
There are several exhibition rooms for art collections to place objects to be comfortable, awake, and maintained from the nosy hands of visitors. The showroom is divided into several sections (Priyanggono, 2018: 27)  Collections of artistic value, of course, are decades old; some are even hundreds of years old. It is interesting to study how to care for, safeguard, protect the collection of art objects so that they can last for hundreds of years and can be seen until now. Is there a special strategy implemented in its maintenance? Therefore, it is essential to know about the arts of conservation to provide knowledge about the maintenance and protection, and care of art objects and other cultural collections. Also, mapping on the development of conservation of art objects and other cultural products needs to be described in managing them. Students, especially Art Management Department and the wider community, should know about it to care for, maintain, and inform the number of works or objects of art collections and cultural results from the past in the global community.
Of the many art collections at Sonobudoyo Museum in Yogyakarta, what is interesting to study on this occasion is the conservation of classical mask art. It is undoubtedly new knowledge because these masks reflect various human and animal characters. More interestingly, it will reveal Panji, Ramayana, Mahabharata, and other stories. As additional information, all masks in the museum's collection from Bali, East Java, Central Java, West Java, and Yogyakarta are made of wood.
Based on the brief outlined above, the problem formulation can be presented: What is the art conservation strategy, especially the treatment of classical masks at Sonobudoyo Museum, Yogyakarta? Are there any specific means or media used in the conservation of classical mask art at the Sonobudoyo Yogyakarta Museum? Why does Sonobudoyo Museum store and collect works or objects of mask art from Yogyakarta, East Java, Central Java, West Java, and Bali?

Discussion
The paradigm used to find solutions to the above problems is carried out through art conservation. Conservation comes from the English word conservation which means preservation or protection. Arts includes works created by humans, including fine arts, performing arts, and recording media art that expresses the ideas or imagination of the creator so that their beauty and emotional strength are appreciated. Thus, art conservation includes an activity that provides knowledge about preservation, maintenance, and protection, as well as being able to inform works of art and cultural products in general that are handled to perform optimally in the community. Conservation of arts also includes mapping the development of conservation of art objects and other cultural products that need to be described in managing them in museums, especially aspects of protection, development, and use for the benefit of the wider community.
In Yogyakarta, there are various forms of historical traces or legacy of traditions, culture, and art centers that have long traversed their history so that they can be used to trace the "remnants" of arts that have lived until now. Talking about Yogyakarta, it cannot be separated from Keraton Kasultanan Yogyakarta (Yogyakarta Sultanate Palace) and Pakualaman Temple, which become the center and beginning of cultural activities reflecting great qualities. These extraordinary qualities are illustrated in the city planning design arranged concentrically as Catur Gatra Tunggal (four forms that make up one unit). Catur means four, gatra means form, and tunggal means one. Keraton Kasultanan Yogyakarta becomes the center of civilization, the square is the public space for community, Beringharjo market is the center of economic movement, and the Grand Mosque is the foundation of spiritual life (Tsani, 2018: 65-67). Around Yogyakarta, there are also majestic temples, such as Kalasan, Prambanan, Ratu Boko temples, and other temples that confirm Yogyakarta as the center of civilization. Apart from temples, many museums play a huge role in managing various collectibles. Some museums in Yogyakarta are Vrederbug Fort Museum, Monjali, Dirgantara Mandala, Bahari, and Sonobudoyo. Therefore, Yogyakarta has multiple images. With this image, Yogyakarta is known as the City of Culture, the City of Arts, the City of Patriotism, the City of Education, the City of Tourism, the City of Gudeg, the City of Books, and the City of Murals (Abiladiyah, 2012: 118-148) as well as other the city images, both built from social and physical realities.
A museum is a place to store, care for, present or exhibit and preserve cultural heritage. Based on this, a museum is also a place for research, education, and entertainment purposes. Through this aim, the museum as a permanent, nonprofit institution, serves the community's needs, is open by collecting, conserving, researching, communicating, and exhibiting cultural objects to the broader community, as what happens at Sonobudoyo Museum Yogyakarta (Suryandaru, 2018: v-vi).
There are around 800 collections of tapelmasks that are well preserved at Sonobudoyo Museum (Riharyani, 2015: 2) Topeng, 2015). These tapel-masks are categorized into heritage as inheritance, legacy, and heirlooms, products of past culture.
The form of inheritance with Nusantara art and culture values can take place through formal education in schools and informal education channels, such as around family environment and in the community, such as in museums. Owing to the inheritance process, tapel-masks can be preserved and maintained until now. To avoid the extinction of artistic and cultural heritages, including Nusantara tapel-masks, heritage protection and preservation is substantially important. The importance of preserving heritages covers not only a philosophical meaning as a performance medium serving the social and ritual functions, but these heritages also tell a long historical journey, and some of them keep tens or even hundreds of year-old stories. Nowadays, the masks have functionally been developed into product prototypes, "cindramata (souvenir) masks" (Hendriyana et al., 2020: 74).
Tapel-masks museum collections preserved to this day came from donations from Mangkunegara VII, Anak Agung I Gusti Bagus Jelantik (King of Karangasem Bali), and the results of Cultural Congresses in Yogyakarta, Surakarta, Surabaya, Bandung and Bali. Apart from presenting scientific papers, various cultural objects and performing arts from Java, Sundanese, Madura, and Bali were also exhibited in each congress (Margono & Priyanggono, 2018: 9-32). Tapel-masks that were donated were found in 1885, namely the Subali and Sugriwa tapels in Yogyakartanese style, according to the collection records. However, based on the traces of ornaments that adorn the tapel and the results of the experts' observations, it looks more Surakartan style. To this day, the tapels have been preserved, protected, and well-maintained.
Treatment of tapel-masks starts from the beginning of the material in the form of wood. The woods commonly used for masks are pole, sengon, jaranan, and waru woods. Tree logging is conducted during the dry season. Mask makers can choose the trees that live and thrive along with the various other growing trees in one place. Trees or wood materials used as tapel-mask materials growing that way become "kiyeng" or very strong and have a strong resistance against wood-eating termites.
In Bali, the initial step of finding the woods for mask materials was based on sekala (scale) and niskala (abstract) calculations. Sekala is the visible aspect and related to the calculation of wuku/sasih/ good month (Third-Fifth month or September-October). Niskala, is the invisible aspect, including a request to the power of the universe, spiritual energy through God the Creator by carrying out the stages of ritual activity. According to Kodi (2020), after the trees are cut down and cut into pieces, they form the materials for tapel-maks. The next steps are traditionally carried out by the following process: • The wood is cut to the size of the mask and soaked in seawater for three to four days so that the wood pores absorb the salty seawater. The wood is cut to the size of the mask and soaked in seawater for three to four days so that the wood pores absorb the salty seawater. After soaking the wood into seawater, it is dried on a ledge so that the seawater dissolves or drips out. • Once dry, the next step is soaking the wood using fresh water so that the salt dissolves in the freshwater. • The next step is draining the wood from freshwater or smoking it for two or three weeks to dry it inside and out thoroughly.
• Ngerencana is the mask-making process based on dewasa ayu (good dates) according to the idea of the desired shape of the tapel-masks, followed by nuasen, which is carrying out a ritual ceremony so that the process of tapelmasks making could run smoothly. • Makalin is the process of working the whole tapel-mask form by boiling the mask using finely ground glugu. Glugu is a kind of orange volcanic rock that contains sulfur elements. Another way can also be done by boiling a mask using trusi, a type of mountain rock containing poison, sulfur so that the mask will appear blue. • The masks are dried, then smoothed, and rubbed with fine sandpaper according to the design shapes before being painted for the finishing process. • Before being used for other activities, the masks that have been 'finished' or nelesin as a final form need to go through a process of sacralization or purification according to their purposes. • The mask is ready to use for its intended purpose. If the mask is often used for dancing or other activities, the mask will be durable and well maintained because the pores of tapel will absorb heat and even absorb the wearer's sweat. • The next treatment uses 'bebase' or Balinese spices, such as dried jebugarum (nutmeg), pepper, cloves. All of these are placed in katung (mask storage). • Ritual masks are routinely purified once every 210 days so that the magical power is attached and becomes one with the masks. This step makes the mask to be a sacred object of metaksu (life force). What about the masks that are collectible at Sonobudoyo Museum? Since becoming objects in the museum's collection, tapel-masks are certainly no longer used as dancing properties. According to Sustiyadi (2020), as Head of Collections, Conservation and Documentation explained that tapel-mask are treated preventively, meaning that the mask is stored in a storage room at temperatures between 18 and 24 degrees Celsius. The proportion of relative humidity is between 45 and 55%, with ultraviolet light not exceeding 75 microwatts/ lumen and light intensity not exceeding 200 lumens. Keep in mind that these tapes are made of organic material, such as wood, so these masks are very much affected by temperature, humidity, ultraviolet, and light intensity.
Apart from preventive maintenance, tapelmasks are also treated curatively by conservators by trained conservators in charge of conserving the art of the masks in the following manner: • Mechanical dust cleaning uses a brush and vacuum cleaner, especially for tapel-masks stored in open showrooms. • If there are stains on the tapes, then these masks are cleaned with some liquid, including water, to remove the dirt; cotton buds are also needed. The cleaning process must be done slowly. If the stain can be lifted, then cleaning with plain water is considered sufficient. • If water does not get rid of stubborn stains, try using a low-level alcohol solution of about 3%, the process is the same as using water.      • If you cannot remove the stain with low alcohol content, you can use a very low concentration of white spirit solution. However, if the white spirit solution causes tapel-mask dye to wear off, this process should not continue. • If parts of the mask are missing or damaged, restoration or repair is necessary. For mask patching, suitable and reversible materials can be used; besides that, you can also use sawdust in accordance with the type of wood, tapelmask material mixed with fox glue. For the finishing stage, two ways can be done, the first one is by painting the masks according to their original color, and the second one is by leaving as it is (unpainted) to show that the part has been restored. Maintaining and caring for tapel-masks to be durable and resistant to wood-eating termites, according to Narimo (2020) it can also be done in several ways, starting from the most effortless process, including: • Soak tapel-masks with clean water to reduce the oil content in the wood that causes termites to appear. • Clean the masks with insecticide around the surface of the mask using a soft brush. • Cool the masks at certain times, but do not expose them to direct exposure to the sun. Then store them back in the storage room. • Provide mothballs or plant roots in the storage room as a drying medium to get rid of the fungus. • Treatment of the mask storage room is carried out periodically to be well-monitored. Some important aspects to note are humidity, light, and room temperature because tapel-masks and their environment become a unit to support excellent and integrated care. Collectible maintenance does require conservators who are experts in their respective fields so that the art objects and collections of aesthetic, artistic, and historical value can be preserved. Such cultural inheritance can also be used as a tourist attraction, as held in Kelanting Village, Tabanan-Bali (Purwanto, 2013: 121-127). During the implementation of the "new normal," performances of tourist art attractions are also held at Pendapa Museum Sonobudoyo Yogyakarta. Below is the mask collections process that is conducted periodically so that all mask collections are maintained, safe, and comfortable to inspire the following artists.

Conclusions
Art conservation, especially tapel-masks, has been carried out by undagi topeng (mask makers), both traditionally passed down from generation to generation and self-taught. The mask makers learn the theory and practice of conserving tapel-masks from their ancestors. Now, in this revolutionary era, along with media or technological tools, it is necessary to master the knowledge of care, maintenance, and protection of art objects, including collectibles, such as masks that can be studied formally and documented at Sonobudoyo Museum in Yogyakarta. From this continuous learning process, it can then be developed to support the skills of conservators.
Moreover, masking arts as a collection object that has artistic, aesthetic, and historical value does require the development of art conservation knowledge at a substantial level to maintain the resilience of tapel-masks so that they remain known and known to current and future generations, both as a medium of art performances and museum collections. Sonobudoyo Museum has played a significant role in saving Nusantara masking arts, especially Javanese and Balinese masks, and is a place to re-read the existence of masking artists according to the local spirit and era.