Conservation of THE SCREEN (Left Part) in Building for Enjoying Lush Scenery

Conservation Practice at the CRAFT, the Palace Museum, September to December, 2014

Other Members: LIU Renhao; WU Jiabao, the Second Class of the CRAFT and Tsinghua University

Supervisor: Gregory Landrey

Object No.: 故 198787

Background

The screen stands in the middle of the first floor of Building for Enjoying Lush Scenery, facing south. As the picture indicates, the screen recorded is the highlight part, which is the left part of the screen, when facing it. The object consists of three main screen parts, forming a trapezoid. Every screen is made up of wood frames and lacquer panel in the front, and gilded lacquer in the back. Upon the panels are the “cap” like components, and below that are the basements. All the connections are joined together by mortise and tensions. The screen dates from Qianlong’s period, almost three hundred years ago. It was located in Building for Enjoying Lush Scenery, the Qianlong Garden. Exposed in the environment, full of grime and dust, it also suffers from inlay detachments. Falling inlay components can be found all round the screen on the ground. And any movement may cause more damage.

Construction and measurements

The left part of the screen was joined to the other parts mainly by mortise and tenon.

The screen stands on the basement, stretching two tenons into the grooves of the basement.

For the single unit, the structural frame uses the Zitan as veneer and another kind of wood as inside ground. The joints cannot be seen directly.

Materials

Inlays

Considering that there are different kinds of inlays adhered to the bases, different ways of adhesion are found in the screen. On the lacquer and plaster layer, the coating is put onto the whole screen board and attached to the main structural frame, only some part of it was cut off to paste the decorations. According to the properties of materials, we sort the craftsmanship of adhesion into the following kinds:

Rocks

All the lacquer as well as the ground layer was cut off, and the board was made rough for pasting heavy things. Animal glue may be used as the UV experiment indicates.

Flowers and leaves

Chrysanthemum has a complicated shape, so they cut off the lacquer layer in regular shape, and used a piece of wood as the base and animal glue as the adhesive to connect the bone flower and the ground layer.

Other flowers and jade leaves were stick onto the ground layer with the lacquer layer cut off in the same shape. Bulks of adhesive are left on the screen, which seems to be semi-transparent, fluorescing under UV light. Guess is if it is sticky wax.

None of them was stick to the lacquer layer directly.

Condition

The screen used to stand on the first floor of Lush Scenery. The lacquer on the panels has lots of tiny cracks, and the inner wood frame also has small deformation,these may be coursed by the change of temperature and moisture. All the materials are in certain extent of deterioration. Most of the inlays of the screen are unattached, easily falling off when moved. To keep them still and save during convey, blue tapes are used to fix the parts. Back to the studio, blue tapes are carefully removed. People working on that tried to remove nothing but the tapes. Still some degraded lacquer fragments and dirt are stick to the tapes.

After examination, we sorted the problems on the screen into following groups:  Loss: The main problem of the screen. Most of the inlays have been lost. Might be caused by degradation of the adhesive. The Shrinkage of the lacquer leading to the lessening of inlay grooves also might be one of the causes.

Loose: Mainly caused by degradation of the adhesive. Lots of the inlay parts are loose.

Lifting: The left decorative frame is lifted, due to the degradation of the adhesive. Also, some long, thin inlays are lifted for the same reason. For example, the tree figure is lifted because one side of it is fixed, while adhesive of the other side has degrade. Some areas of the lacquer are lifted. According to the different locations, they may appear to be detached or bubbled. These phenomenon are caused by the different contraction percentage of the lacquer and wood.

Breakage: Some inlay parts are broken for the materials are fragile. For instance, the amber chrysanthemum.

Crack: The beige lacquer on the panel has crack on it. It mainly appears on the edges. The change of moisture and temperature in the environment may cause the contract and expand of the lacquer. The change of volume may finally lead to cracks.

Discoloration: Most of the materials tend to be discolored, due to degradation. Some parts of the wood frame are branched. Might be influenced by sunlight or leaking.

Biological: Insects are inside the screen. Several spiders are witnessed as well as the dead bugs. Molds were also often found on the screen. They may be caused by the high moisture in the air and the dusty surface.

Other: Human activities. Including the blue tapes’ effects.

Treatment

Rationale

The screen is conserved for exhibition. Aesthetic need is the most important goal. Therefore, at first, we wonder if we can make up all the loss and clean it up. However, as there are too many losses on the screen, it is impossible to replicate them all. And for ethical reasons, it is of question whether to do thorough cleaning. After discussion, the group members agreed to do the basic cleaning and consolidate the inlays. The cleaning should be controlled, keeping the historical trace. As for the loss parts, we will try to replace the fallen parts and leave the missing ones as it is. One obstacle we face is that to do the cleaning of the back of the panel, we should turn it over. But the inlays of the front are so loose. So we decided to do the cleaning and consolidation of the front first, and then turn the screen over and do the following works.

Cleaning

Structural frame: First, use the soft brush and vacuum to wipe out the dust. Then a test cleaning is applied. We try to use the sponge to get dust off the wood part. As for the lifted part, we cut the sponge into wedges and use them to hold the lifted part in case it hurts the lacquer.

Decorative frame: Same as the structural frame, soft brush, vacuum and sponge are used to clean the decorative frame. The curve area might not be cleaned thoroughly, but agreement is reached that leave it makes no harm and shows the pattern better.

Lacquer: On the lacquer panel, using sticks keeping the detached parts of the decorations, we used brush and vacuum to remove the dust and other pollutants.

Inlays: Use the sponge softly on the inlays to remove the dust.

Consolidation

For the inlays, we took off the loose part one by one, recorded its location. Cleaned the back of the inlay with mineral spirit for better bonding effect. Cleaned the contact area on the panel with brush and vacuum.

Brushed B72 (5% acetone) solution on the sticking area as the barrier coating.

For those above the plaster or the wood groove, we used sticky wax to stick them. As for the inlays on the lacquer, we use B72 solution in the forth step to stick them. Some inlays were stick to the panel with an adhesive that is not stick wax, which is whiter than the old sticky wax on the panel. It may be sticky wax with lead in it or some degraded sticky wax, so we took a sample of the adhesives for further analysis. Then we stick these inlays back to the panel by sticky wax. The sticky wax is not brushed all over the back of these inlays but at several dots of areas, for we want to keep the original adhesive as well as consolidate these parts.

For the wood figure, We did nothing, since there are wood nails (possibly failed) between the panel and the wood figure. Pulling out the nails from the holes and pushing them directly back in to the wood panel may do harm to both of them. Still under discussion.

Further discussion is required for consolidation of the decoration frame and lifting lacquer:

After consolidation, we safely turned the screen back, conducted dry cleaning on the glided lacquer surface and frames.

Loss Compensation

The loss of inlays especially the big rocks does harm to the aesthetics of the screen. The discussion of compensation lasts for months. The final plan is to use balsa wood painted with neutral color, cut in the right shape, to fill in the large area of rocks lost, at the bottom of the screen. The loss of flowers, leaves and other small figures is not distractive, we leave it as it is.