Restoration of damaged bronzes in the collection of the Changzhi City Museum

Restoration of damaged bronzes in the collection of the Changzhi City Museum

Journal of Changzhi University, 2018.03 Wang Yumei (Changzhi Museum)

Abstract: Chinese bronzes have a long history and appear all over the world, which is a world-famous symbol. The bronzes excavated from the watershed of Changzhi City in the 60s and 70s are a witness to history, and the broken bronzes excavated at that time have been restored to restore their original appearance, and various exhibitions have been launched to let the majority of tourists understand the history of Changzhi.

Most of the bronzes in the Changzhi Museum's collection were excavated from the watershed of the 1960s and 1970s. These bronzes were originally preserved in ancient tombs or kilns and buried underground for more than a thousand or thousands of years. Due to the long-term erosion of groundwater and the squeezing of accumulation, most of the artifacts have been damaged or deformed when they are unearthed, and some are even fragmented and unrecognizable, like a pile of waste copper pieces. Due to the era and many other factors, for all kinds of cultural relics unearthed, only according to the requirements of the time, after recording, drawing, photographing, and sorting, the artifacts were separately stored.

Of the hundreds of bronzes in the collection, nearly two hundred are damaged, of which more than 90 are badly damaged and mutilated. In 1993, our museum set up a cultural relics restoration room, which targeted the restoration and protection of the collection and newly excavated broken cultural relics. At first, we only repaired the bronzes that were less damaged. Later, our museum formulated an intention to jointly organize watershed data with the Provincial Archaeological Research Institute, so we repaired more than 90 severely damaged bronzes one by one. Through several years of efforts, most of the damaged bronze relics in the collection of the museum have been restored to their original appearance, especially some of the original severely mutilated and regarded as waste copper pieces, most of which have been identified as first- and second-class cultural relics by the state and provinces after restoration, so that these cultural relics have been effectively protected and fully utilized. Here, we will introduce the restoration of some artifacts.

First, the bronze before the restoration of the damage

(1) Four-beast ear ring crab scale bronze hammer, watershed M269:33, excavated in 1972[1]340, the mouth edge is broken into three segments, and the abdominal part is fragmented

Broken into multiple fragments of different sizes, and the missing part of the pattern has been missing, the bottom and abdomen are separated, only one-third of the part can be spliced with the abdomen, 4 animal ear rings have 3 fall off and miss a ring, of which the horns of the three animal ears have different degrees of mutilation, the largest fragment is 73 * 30 cm, the smallest is only 3 * 5 cm, a total of 13 fragments.

(ii) Oblique horned beast cotton three-lady cover ding [1]264, watershed M25:37, excavated in 1962, jointly detached, the mouth edge is broken and enough to separate the bottom, the middle abdomen is broken into small pieces and mutilated part of the ornament, one foot is separated from the lower abdomen and the foot and hoof are mutilated, the cover is broken into multiple pieces and mutilated, and the fragments are a total of 14 pieces.

(3) The head of the three-hoofed beast with the animal face is erect and the ear is bronze, the watershed M26:1, excavated in 1962, the mouth edge is broken into four sections and missing one ear, the three feet are separated from the abdomen and one foot is broken into two sections, the bottom is broken into three pieces, the lower abdomen is mutilated, and the lower ornament is mutilated 18 * 12 cm, and the fragments are a total of 14 pieces.

Copper furnace with chain of crab pattern, watershed M26:12, excavated in 1962, the whole instrument was broken into 13 pieces, missing a foot, and the furnace chain had two breaks.

(4) The straight edge of the folded wall of the cockroach pattern is the copper fin of the double animal ear, the watershed M269:29, excavated in 1972, the bottom cover has been twisted and deformed, there are two folded walls broken and separated from the body, and the four animal ears fall off.

(5) Cockroach-patterned bronze bell, watershed M25:5, excavated in 1962, the whole vessel was broken into four pieces and deformed.

2. Bronze restoration

(1) Cleaning

Cleaning bronze is to wash off the attachments on the surface of bronze, generally with distilled water or acid to wash away the soil, minerals, calcareous deposits on the surface of the utensils. The cleaning reagent uses the reagent with minimal damage to the utensil. Generally, 5% to 10% citric acid solution is used to soak to remove soil rust [2]95.

(2) Shaping of bronzes

In the practice of restoration work, we have explored a new set of heating and shaping methods, which are particularly effective for excavated ancient bronzes with large damage and deformation, and deformed bronzes will produce processing stress and process hardening during the orthopedic process. By heating, a certain amount of stress can be reduced, the toughness and plasticity of the metal can be improved, the rupture phenomenon caused by the traditional process can be avoided, and the integrity of the utensils can be maintained to the greatest extent. The watershed M269:29 and the watershed M25:5 yong bell were repaired after heating orthodontic correction.

Since we had limited conditions, we did not have an oven and heated it with an electric stove. First make a baking rack, the height is 15 cm from the stove surface, put the shaping parts on the stove rack to bake and heat, the temperature begins to change with the eyes to observe the color of the surface of the utensils, and then raise the baking rack by 5-8 cm, continue to heat for about half an hour, and then according to the deformation of different utensils and parts, with the wooden molds that are matched in advance, different methods and different tools are used to correct, such as top pressure, extrusion, support, hugging, stranding, etc. The bronze grate is corrected by the twisting method, that is, the upper and lower with a suitable wooden board to clamp the utensil, the two wooden boards are tied with wire between the two ends, and then slowly tightened, until the utensil returns to the limit, so that it remains under pressure for a period of time, and then the loose pressure continues to heat up, and then use the same method to orthopedic, the orthopedic process needs to often adjust the twisting site, so repeat the heating and stranding several times, until the regular. The last or two stranding orthopedics should cause the deformed part to be pressed a little in the opposite direction, that is, a little over the head. When it is loosened, it will automatically bounce back to its normal position. The bronze yong bell is corrected by using heating and top pressure.

Third, the welding of bronzes

The repaired objects, first of all spelled, mark, if there is a deformation of the fragment first shape correction, and then according to the degree of oxidation of the utensils and fragments, the development of different welding schemes, the general utensils themselves have the phenomenon of uneven tire thickness, coupled with the burial around the accumulation is different, the same is an artifact, different parts and fragments, the degree of oxidation is not the same, some places copper as new, some only a little copper core, some are completely oxidized out of the birth, therefore, Different materials and methods are used for welding and bonding on the same piece of artifact. Soldering using the traditional lead-tin soldering method of soldering, generally is the small fragments welded into large pieces, and then welded together, welding focus on mastering the arc and flatness of the entire instrument shape. Where there is a slight misalignment, the knife and steel file are used as the pressure rod, inserted into the weld orthoped to correct the spot welding, and then welded. Where the copper quality is poor, it is fixed by electric welding, and then it is bonded with 502 glue or AB glue, and 502 adhesive is used for complete oxidation and birth.

For larger, thicker tire wall utensils welding, it is necessary to increase auxiliary welding, because the utensils are large, heat absorption and heat conduction is fast, when the soldering iron is close to the weld, the heat on the soldering iron is quickly absorbed and dissipated around the weld, and the heat in the welded place cannot reach the fusion point in the solder, so the place where the weld is welded is virtual welding. Therefore, when welding large utensils, a small blowtorch or AC-3 automatic fusion welding machine is used, and the welding joint is welded synchronously with the soldering iron, and the welding joint is both reliable and light and flat. For example, the four-animal ear ring crab scale bronze hammer, the four-sided ridge, the cockroach pattern with chain copper furnace, the Yong bell, etc. are welded with lead and tin, and the oblique angled beast cotton three-lady cover ding is welded and bonded. In short, according to the tire quality of the utensils, different welding techniques are used to restore them.

Fourth, the replenishment of bronzes

General bronze through shaping, welding, bonding and other technologies, can not achieve the expected purpose, most of the utensils and defective parts need to be replenished. There are three ways to replenish:

(1) If the defective part is plain and without lines, it is directly annealed with a red copper plate equivalent to the tire wall, cut down according to the size of its size, and beaten according to the curvature of its complement.

(2) The defect is ornamented, the defective part is small, the tire quality is good, directly on the utensils to make the same plaster model as the defective part, and then use the plaster mud (sculpture with mud) to roll out a mud piece of the same thickness as the tire wall, paste it on the plaster fan and then make another model, open and take it out after solidification, repair the gate and steam port and then close the bundle for baking, the baking rack is from high to low, that is to say, the temperature when baking is low to high. Start baking at a distance of 30 cm from the oven for a period of time, and slowly reduce to 15 cm baking, this kind of baking from low temperature to high temperature can dry the water thoroughly without breaking the plaster fan. After the gypsum fan is dried, the melted lead and tin material is poured into the gypsum fan, to be cooled, it is trimmed, and the defective part is supplemented to the mutilated part of the utensil; the mutilated part is large, the tire quality is good, and the gypsum fan is reproduced by the method described above, without baking, directly press the paraffin wax, take out the wax type, trim the ornament clearly, and then combine it to the broken part, check whether the ornament on the wax type, the tire wall is consistent with the utensil, when to remove it, use modern technology to pour into a bronze patch, and supplement the missing part of the utensil. The three-hoofed beast head of the beast was used in this way.

(3) For the tire quality completely oxidized and the ornament is mutilated, the mud model of the ornament and shape can be directly printed in the same place of the utensils with paste mud, and the prepared filler is gradually made into a colloidal patch equivalent to the wall of the mutilated place on the mud model with 502 glue, and supplemented to the mutilated part of the utensil. If the strength is not enough, you can use a 0.3 mm copper sheet annealing to make up a layer in the missing part, and then drill some 4 mm-sized holes to facilitate bonding with the rubber patch. The fragments of the four-beast ear ring crab scale bronze hammer and the oblique angled beast cotton three-lady cover are all restored one by one using the above methods.

Fifth, the coloring of bronzes

Through the previous steps, although the shape is complete, the color is not yet consistent, so it is necessary to color. Before coloring, the repaired utensils are first immersed in tap water (hydrochloric acid is coated with hydrochloric acid on the weld during welding) for 5-12 hours, so that the hydrochloric acid around the weld is completely decomposed, the oxide layer on the weld is washed off with a toothbrush, and then the file level weld and patch are repaired to the inappropriate place, and then the weld and patch bite the old (acetic acid) and then wash it. When coloring, first look at the bottom color of the original surface of each piece of coloring utensils, after the mixing, first smooth the weld and the patched parts consistent with the utensils, after drying, sand smooth and flat with water sandpaper, brush the same base color on the ornamental patch part, and then brush up layer by layer according to the color of each piece of utensils, and finally achieve close to or consistent with the color around the part.

From 1993 to the present, in the past twenty years, we have overcome various financial and technical difficulties, continuously repaired the bronzes in our collection, restored their original appearance, and continuously displayed and exhibited various restored artifacts, so that more people can appreciate these bronze treasures left to us by history and understand the history of our Changzhi more intuitively.