Volume 5, Number 2, June 1983, pp.5-6
The paintings conservators at Balboa Art Conservation Center were recently faced with the problem of how to treat a series of 9 paintings with problems related both to paint and to paper. The paintings were illustrations of scenes from the Book of Mormon done by the Mormon artist, C.C.A. Christensen, probably around the turn of the century. Christensen was a Danish immigrant who was converted to the Church of Jesus Christ of Latter-Day Saints and was one of the early pioneers who made the journey from the East to Utah.
The nine scenes from the Book of Mormon were executed on cardboard approximately 2 mm thick and were used as teaching aids for the Sunday School for many years. The cardboard supports may have been commercially prepared for artists' use. Each has a smooth, matte black coating on the reverse with a small stamp of a sphinx in the center. There is a white ground layer on the front with an overall texture of small stipples. The illustrations were done with oil paint using a direct technique which retained brushmarks but did not create significant impasto. There was no varnish layer on any of the paintings.
The paintings were received in very poor condition. The cardboard supports had suffered from much handling. The corner and some edges were delaminating and were bent and torn. In addition, they had been exposed to humid conditions and/or to direct contact with water, resulting in severe planar distortions--complex warps and bulges. In several cases ripples along the top edge were well over an inch in depth. The cardboard was quite stiff and brittle; it was feared that attempts to flatten it would cause it to break.
The ground and paint had cracked and often flaked away in places due to the deformation of the cardboard board. There were numerous area of cleavage. There were also stains from spills, abrasions both front and back from repeated stacking, and heavy surface grime overall.
The first choice was how to safely flatten the paintings. It had been suggested that complete or partial transfer, peeling the cardboard away from the revere, might be necessary. This would have been extremely time-consuming and risky and would have compromised the integrity of the object. Janet Ruggles, paper conservator at BACC, suggested that a gentle way to relax the cardboard would be to place each painting on a piece of raised Homosote board in a humidity chamber and raise the humidity gradually allowing the Homosote to act as a buffer. Light weight could be placed on the painting to coax bulges down gradually as the support released. When sufficient flattening was achieved the humidity could be gradually decreased with the painting remaining under weight.
We decided to pursue this option and achieved excellent results. The humidity chamber consisted of a Fome-cor box lined and covered with polyethylene. It was deep enough so that the painting placed on 1/2" thick Homosote board could be raised approximately 2" from the bottom and had about the same amount of clearance above. Four dishes of water were placed in the chamber, one at each corner. The humidity was monitored with paper indicators made by Multiform Desiccant Products, Inc. It rose gradually over several days to about 85 and remained there.
Before each painting was actually placed in the chamber, all loose paint was consolidated with Jade 403 PVA emulsion, and the surface grime was removed. Once in the chamber the painting was checked every day and weights were moved or increased as the painting required. In some case flattening was accomplished in 3 or 4 days. The most distorted paintings required more than 2 weeks of humidification and weighting (and waiting!). Once each painting was flat, it was dried under vacuum, face up on layers of newsprint on the hot table which was warmed to about 100° F. Delaminating corners and edges were then consolidated with Jade 403 and allowed to dry under weights.
It was decided to mount the flattened paintings onto aluminum honeycomb panels as auxiliary supports. The paintings will travel, and the mounting on solid supports will allow them to be framed and handled safely. Each aluminum panel was covered with a satin weave fiberglass interliner adhered evenly with wax-rein. Wax was chosen as the adhesive, not for its penetrating property --there was no appreciable penetration through the coating on the reverse of the cardboard--but because it holds firmly enough to keep the distortions from reappearing, yet is easiest to reverse on a solid support.
There remained some unevenness in the thickness of the cardboard in places where direct exposure to water had expanded the material irreversibly. This showed itself when the paintings were drying face up under vacuum. In order to keep the unevenness from showing on the surface, the paintings were attached to the prepared panels face-down on the vacuum hot table over 1/8" thick silicon rubber sheeting as cushioning. Vacuum pressure of under 1" mercury was used and the heat was raised to about 140° F on the table surface, enough to insure good overall tack, but not enough to make the wax actually flow. The paintings appeared firmly attached and the surface plane was flat, but there was no alteration in the texture of the paint or ground.
Since the painting had never been varnished, another choice remained--to varnish or not to varnish. Consultation with the curator and with other conservators who have treated Christensen paintings revealed that there was no feeling that the paintings were meant not to be varnished. Also, the nature of the damages, including stains, would have made it difficult to achieve good inpainting results without varnishing. It was also felt that a varnish layer was desirable for protection of the paint from grime. A mixture of 3 parts Matte Soluvar to 1 part Gloss Soluvar diluted 1:1 with petroleum benzine was brushed on the paintings. This coating fulfills its protective function, yet preserves the slightly matte look which the paintings had. Inpainting was carried out with pigments ground in Acryloid B-72. A final light spray coat of Acryloid B-72 was applied after inpainting. Black polyethylene extrusion lip-over edge stripping was stapled to the edge of each panel with the lip raised slightly above the face of the painting as a further protection. We were very pleased that the paintings could be successfully consolidated then flattened using the humidity chamber without resorting to removal of any of the original supports in spite of their seemingly irreversible damage.Betsy Court
Timestamp: Thursday, 11-Dec-2008 13:02:26 PST
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