BPG Composite Structures

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American Institute for Conservation (AIC). "BPG Composite Structures." AIC Wiki. May 10, 2025. https://www.conservation-wiki.com/wiki/BPG_Composite_Structures.

Collé Paper

The image-bearing layer, a fine delicate paper trimmed smaller than the plate to be printed, was adhered to a thicker soft-sized plate paper during the printing process. The two layers were adhered by a sprinkle of dry starch on the verso of the damp tissue (19th century), by starch paste (20th century), and most recently, by commercial pastes (1940s?). Apparently, the prepasted and dried paper was placed on the inked metal plate, paste side up. Damp, relaxed plate paper was then placed on top and the three layers (printing plate and plate paper) were pressed together through the press.

A variety of papers were used in the collé process. From the 1750s to the 1830s paper was made from bamboo and mitsumata fibers by the Japanese in imitation of Chinese calligraphy paper (this paper is now more correctly called China paper); it was introduced to Europe as wrapping/packing paper and adapted for use in line engraving, particularly for steel engravings. European or “Mock India” papers were introduced in the 1830s and Bible paper in the mid-nineteenth century (see Japanese Papers, especially Gasenshi and Artists' Printing Papers: India Paper). Collé or laid Western papers are also encountered in 19th and 20th century prints (e.g., French artists, nineteenth century American historical prints, and prints by Kuniyoshi).(KN) The collé paper sometimes was chosen to blend with the color of the plate paper, sometimes to contrast with it.(CS)

Inherent Problems

Plate paper is porous and often prone to foxing and water stains.

Treatment Observations

• During aqueous treatments the collé paper layer may separate partially (discrete scattered bubbles, along edges, or at corners) or completely from the plate paper. However, there may be strong physical attachment at heavily printed areas; use caution when attempting to completely detach the collé paper. Impression quality on chine can be compromised during aqueous treatments.

• Use a suction table to control aqueous treatments and discourage separation. Use damp blotters and webbing supports to pull out the staining without separating the two layers.

• If there is no indication that delamination will occur, float washing may be used. Have the suction table set up in case it is needed. To reflatten bubbles that may appear, remove the print from the bath and leave it on blotters until the collé is almost dry. Have on hand a dilute solution of cellulose ether. Encourage the bubbles to dry more quickly than the collé paper around them by touching their tops with the soft edge of torn blotter scraps. As they dry, they will grow smaller. Do not allow the perimeter to dry completely if there is still height to the bubble. If necessary, brush a little water around the bubble's edges to keep the deformation soft and rounded. Avoid linear drying patterns, like “ledges.” When the bubble has only the faintest degree of moisture left and has almost shrunk completely, brush on a tiny bit of dryish cellulose ether, wait for further shrinkage and less adhesive tack and then tap into position with the rounded edge of a warm tacking iron. This technique eliminates the bubbles in the majority of cases. Occasionally, a bubble will not shrink enough to be tapped into place without creating wrinkles. In these cases, puncture the top center of the bubble with a titanium microscopy needle - with the fibers damper than for the other technique, so the puncture will be ragged - and continue as described.(CS)

• Readhesion may be complicated by the fragility of the thin pressed paper, the differences in dimensional responses to moisture, and on the need for precise registration. Supporting the wet chine on Mylar may assist in realignment. (NA) For reapplication of a lifted tissue, use a Mylar carrier and raking light. Have both papers and the adhesive as dry as possible. Starch paste or other adhesives can be used.(CS)

Sometimes text overlaps the join line between papers and often there is a distinct outline of the collé paper on the plate paper, so misalignment will be very obvious.(KN) Impressions on both papers may be impossible to match.

Papier Marouflage

Historically, oversize posters, maps, and embrittled works of art were mounted to cloth linings during manufacture or subsequently by framers and restorers. This was often done to emulate paintings on canvas and increase the cost of drawings or as a solution for handling large works. Canvas-lined drawings are sometimes attached to stretchers and exhibited unglazed. Historically, some drawing papers were mounted onto cloth before execution of the artwork. For example, pastels by Mary Cassatt exhibit her stamp on the canvas.(LP) Posters were often routinely lined to make them easier to handle.(KDB)

Architectural presentation drawings were sometimes executed on watercolor or drawing papers which were mounted to fabric in the studio or purchased already mounted. The latter may have been available as early as 1885/1890. Visual evidence, in the form of regular striations caused by the pasting machine, may be helpful in identifying premounted sheets (Sugarman 1986, 45).

Contemporary artists often choose canvas mounting as a desirable way to present oversize drawings and exhibit without glazing. For some, mounting represents a conscious aesthetic choice. Works are usually mounted to linen after execution by professional mounters, often using glue-paste, starch adhesives, or synthetic adhesives.

Inherent Problems

• Use of incorrect methods and/or materials in the initial mounting may cause planar deformation, wrinkling, uneven attachment/separation, discoloration, etc.

• Objects were often lined with the intention that it would enable easy rolling. Often they were rolled image inward to protect the image. Consequently, this caused compression, cracking, etc. of the paper and media.(KDB)

• Differences in structure and method of manufacture and preparation may cause the paper and canvas to react to atmospheric changes and exposure to liquids and solvents in opposite ways (e.g., mechanical stresses, shearing and loss of adhesion).

• Stretcher/strainer mountings subject the object to more risk of physical damage by puncture, shock that leads to cracking in heavy paint layers, drawing at corners and deterioration of tacking edges.(CS)

• Physical and chemical characteristics of the attaching adhesive represent a further complication - adverse effects of aging/deteriorating adhesive (e.g., yellowing, staining, embrittlement, and decreasing reversibilities).

• Aesthetic surface changes in paper tone, texture, and flexibility associated with fabric and/or adhesive.

Treatment Observations

• Conservation treatments of contemporary works mounted to canvas should acknowledge the aesthetic significance of the artist's original mount. Consultation with the artist, curators, and/or art historians may be required before treatment.

• One option for retaining the historic format of a cloth lining while providing a more compatible and reversible support for a treated object is to provide a separating layer of Japanese paper such as tengujo between the object and the cloth (van der Reyden 1988).

• If the object is on a stretcher/strainer, one should attach a Tycore or corrugated board filler to protect the exposed back.(CS)

• Replacement of a strainer with a rigid, chemically stable support of the same dimensions is often appropriate for items mounted on a strainer. An attempt to flatten tacking edge can cause distortion in image area.(LP)

Compound Drawings

These drawings are usually mounted by the artist or collector to a “secondary” support which conveys both aesthetic and/or historical information. Thus, the secondary support is an integral part of the work with historic significance and should be retained.

For example, Paul Klee systematically mounted his drawings on paper to stiff cardstock; his secondary supports are important aesthetically, as informational devices, the official presentation format, and as examples of the artist's thrift (for more information see Schulte, Ellis, and King 1986, 20–23). For Klee's drawings there were generally two methods of attachment: spot attachment by random or regularly spaced adhesive daubs; and overall mounting with adhesive.

Degas employed several systems for mounting. (See Chandler 1984, 443–448.)

Old master European drawings were often mounted on decorated mounts which complement the drawing and form an aesthetic whole. They may bear collector's marks or inscriptions which help establish provenance. For example, Vasari had a mount designed for his personal collection and Glomy in the 18th century decorated mounts which bear his name or “G” blind-stamped at a corner.(KN)

Inherent Problems

• Spot attached drawings may not lie flat. Some undulation may be expected and may not interfere with an appreciation of the drawing, but draws may be exaggerated and distortions can occur around each adhesive daub. Extreme tensions have been observed to shear and delaminate the paper (on the verso) around the daubs.

• Drawings mounted overall tend to remain in plane with their secondary support, but may suffer from lifting or bubbling.

• In addition, compound drawings may suffer disfigurement from glues, tapes, and framers' notations; from having been cut down or folded to fit into smaller frames; from removal and disposal of the secondary supports.

• Historical mounts may suffer from every sort of chemical, physical, and/or biological deterioration that the primary support is subject to.

• Adhesives can cause staining.

Treatment Observations

• Releasing primary from the secondary support may be desired if there is physical damage, extremely disfiguring distortions caused by tensions in spot attachment, the adhesive is expected to cause stains or acid damage over time, or the primary support is very delicate or weak and has not yet, but could, become drawn or deteriorated.

In making this decision, the conservator should consider the stability of the environment in which the object will be housed and the ability to monitor changes in the object. In excellent housing and environmental conditions and with the ability to monitor the object, a conservator may choose not to alter artist's mounting methods. In the case of the Klee drawings it was decided to retain the overall character of the sheet as well as evidence of past attachment by the artist (for more discussion on this particular case see Schulte, Ellis, and King 1986, 27–28).

• If possible, reattach (or readhere) any delaminated areas using paste alone or with Japanese tissue hinges of appropriate weight.

• Reattach to the original secondary support using hinges. Hinge along all four edges over an isolating layer of lightly buffered Japanese paper (also hinged to the mat) if this is required for isolation from poor quality materials.

• If possible, use ragboard lined Plexiglas spacers rather than an overlay window mat to isolate the work from the glazing. This best presents the original mounted format for exhibition.

Collage

Collage can be composed of various paper and non-paper materials and of adhesives of varying quality and stability. As with other composite structures, decisions must be made as to when intervention is appropriate. Often the artist, particularly the 20th century artist, may have consciously chosen (or chosen to ignore the problems of) materials which are not stable.(NA)

Inherent Problems

• In the case of collage materials, pieces can become individually damaged or cause damage to each other (see King 1978).

Treatment Observations

• If disassembly of a collage is necessary, document the object and its various parts with tracings as well as with photographs before beginning treatment. Mark every shape and have a style of marking to designate support areas versus applied areas. If appropriate, make notes along joint lines about overlap or anything else one may forget over the course of a long treatment. Collages may have applied pieces completely hidden by upper layers (e.g., R. Motherwell). Photograph extensively during disassembly of multi-layers of objects, to facilitate the study of the artist's process by art historians and others.(CS)

• Depending on the media involved, attachments can be held in place during washing by facing with lightweight Japanese paper and methyl cellulose. The methyl cellulose will not release during warm water washing but can be removed afterward with cool water applied with a swab.(DvdR)

• In C. Oldenburg collages, conspicuous masking tape tabs were used to adhere collage papers to the support. In one example, the masking tape was discolored and detaching and with the consent of the curator, the masking tape was removed and solvent used to remove adhesive from the carrier. The carrier was lined with thin Japanese tissue and wheat starch paste and readhered in the original position.(NA)

Restrained Papers

Papers attached to strainers, rigid backings or false margins “inlaid.” Mounting may occur before or after execution of the work, either by the artist, a framer, or by some other person. Papers may be mounted to facilitate handling and display; provide support for weak or especially large papers; mimic the presentation of paintings; and, among contemporary artists, for aesthetic reasons.

• Strainers: Usually the primary support is not attached directly to the strainer but is first mounted to a secondary support of paper or cloth, or to a false margin. The edges of the secondary support may be directly adhered to the face of the strainer. More often, however, the secondary support extends beyond the primary support and is folded around the outside edges of the strainer where it is attached with an adhesive and/or mechanical fasteners (tacks, staples, nails). Sometimes the edges of the work of art itself are folded around the strainer. If the secondary and primary support have been dampened before being attached to the strainer they will have shrunk upon drying and may be under tension.

• Rigid backings: The primary support is adhered overall, along its edges or by random or regularly spaced spots of adhesive to a rigid secondary support. This rigid backing may be of wood, masonite, cardboard, glass, plastic, or sheet metal or it may be a panel constructed of one or more materials (e.g., aluminum honeycomb panel with wooden spacers at edges).

• False margin: The primary support is inlaid into a false margin of paper which slightly overlaps its edges. Ideally the join is achieved using the thinnest of pared margins (approximately 3–4 mm), but sometimes broad and/or unpaired margins occur. A false margin may be added to facilitate handling; control curl of a work that tends to roll up, usually after removal of a previous lining; and reestablish original format, for presentation.

Inherent Problems

• Strainers: Papers are easily punctured, especially as the secondary and/or primary supports deteriorate, becoming weak and brittle. Breaks or tears in the edges of the secondary support may result in uneven tension and planar distortion of the primary support. Delamination of primary and secondary support (which may occur due to environmental conditions or poor materials and technique of fabrication) can also cause uneven tension and planar distortion. Papers may split due to dimensional changes of the secondary support or strainer. There may be some tendency of paper to distort by sagging into the opening of the strainer.

In cases where the edges of the primary support have been folded around the strainer they may be damaged by tacks, nails or staples. Heavy corrosion deposits may exist at these spots. Stress on folded edges may cause rupture of paper fibers, cracking of the paper and flaking of the media. Later attempts to flatten these borders can exacerbate these problems. Abrasion of the folded edges may occur, especially as the work is slid in and out of a frame. A commonly encountered adhesive is animal skin glue. Unfortunately, more often than not, it remains voraciously strong.(CS)

• Rigid backings: Wood, masonite and cardboard panels may warp, placing the work under tension, or they may split or snap. Plastic and metal sheets may be bent or dented and glass may break. Any rigid backing to which a work is adhered overall can harden and flatten the surface texture of the laid lines, felt marks, platemarks, etc. If the work is adhered around the edges or at intermittent spots, it will undergo stress as the secondary support and the restrained and unrestrained areas of the primary support respond differently to fluctuating environmental conditions.

• False margins: Differing dimensional stabilities of the primary support and the paper into which it is inset, as well as the restraining action of adhesive layer, can cause pronounced draws or cockling. Wide or unbevelled margins which are visually incompatible may be aesthetically unpleasing. When unskillfully done “ledges” are frequently permanently pressed into the original work where the false margin overlaps it.(TF) While some view the use of false margins as a measure of protection for the edges of the work (especially one which is frequently handled) others may see extending a drawing with false margins as a violation of the integrity of the object (McAusland and Stevens 1979, 33) and as further stressing often fragile edges.(NA)

• Sometimes works on paper were “drum mounted,” that is wet out, humidified, or in some way expanded with moisture and then laid down at the edges. This, upon drying, kept the work very flat. A puncture or sudden fluctuation in RH can release tensions developed by drum mounting. Also in treatment, releasing one edge or corner could set up tension which could cause a tear or crease.(KDB)

• Contact with poor-quality adhesives and secondary supports may cause acid-transfer to and deterioration of the secondary support. Adhesives can stain papers, can penetrate them to locally change their inherent physical and chemical characteristics and may become irreversible.

Treatment Observations

• Strainers: Papers adhered to strainers may be protected against puncture by fixing a rigid backing to the reverse of the strainer and by proper framing under glass or Plexiglas. If the poor quality of the mounting materials or the deteriorating condition of the work warrant removal from the strainer, treatment options may include the following.

Mimic original “stretched” presentation by removing primary and secondary support from strainer, removing and replacing secondary support if necessary, and then remounting the work on to a stable rigid panel of the same exterior dimensions and thickness as the original strainer. This mounting method would eliminate the danger of puncture. The solid support may be a laminate of several materials including acid-free mat board and corrugated board, paper honeycomb (e.g., Tycore), aluminum panels and aluminum honeycomb. The secondary support may be adhered to the panel only where its edges wrap around the solid support or overall by means of an interleaf layer (e.g., Hollytex, Japanese tissue, etc.) which will permit its easy separation from the solid support. Japanese paper hinges can also be attached to the edges of the primary support and to the back of the new support. (NA) If the strainer is integral to the history of the work, it can be incorporated into the mounting and framing or stored separately (the latter choice often being less desirable). (CS)

Present the work flat by removing it from the strainer and, if necessary, from the secondary support. If the edges of the work have been folded around the strainer they may require humidification and flattening. Flattening may be complicated if the paper has stretched by “sagging” into the opening of the strainer. (NA) The artistic and historical significance of the strainer mount should be considered in determining whether or not the work should be presented flat. If the object is housed in a frame believed to be original, flat presentation should not be undertaken. (CS)

• Rigid backings: Backing removal is often necessary, either to reduce mechanical and chemical threats to the work or to return the work to its original, loose-sheet configuration. Aqueous treatment may help bring back flattened surface texture. (See Backing Removal.) If the strainer is to be reincorporated into a treated object, the object can be protected from the acids within the wood by sealing the wood. Polyester film and Japanese paper, among other things, can be used as isolating layers (van der Reyden 1988).

• False margins: After the removal of false margins light adhesive residues can still cause slight distortion of the edges. Removal of a false margin that was applied to control curl still leaves the problem of flattening which is compounded by perimeter adhesive residues.

References

(See also General References)

Chandler, David. "Edgar Degas in the Collection of the Art Institute of Chicago: An Examination of Selected Pastels." Degas: Form and Space. Paris, Centre Culturel du Marais, 1984, pp. 443-448.

Gagnier, Richard and Anne Maheux. "The Mounting of Over-size Works on Paper at the National Gallery of Canada." Handout Symposium 88, Ottawa, Canada, 1988, 6pp.

Jenkins, Penny. "India Laid Prints Meeting." Paper Conservation News, No. 49, March 1989.

Jenkins, Penny. "Preparation of India Proof Prints." Typescript of notes from an interview with Philip McQueen, Nov. 15, 1988, 3 pp.

King, Antoinette. "Changes of the Collage 'Roses' by Juan Gris." Conservation and Restoration of Pictorial Art. Norman Brommelle et al., eds. IIC London: Butterworths, 1978, pp. 234-238.

McAusland, Jane and Phillip Stevens. "Techniques of Lining for the Support of Fragile Works of Art on Paper." The Paper Conservator 4, 1979, pp. 33-44.

Schulte, Elizabeth Kaiser, Margaret Holben Ellis, and Antoinette King. "An Approach to the Conservation Treatment of Paul Klee Drawings." The Book and Paper Group Annual 5, 1986, pp. 19-32.

Sugarman, Jane. "Observations on the Materials and Techniques Used in 19th Century American Architectural Presentation Drawings." The Book and Paper Group Annual 4, 1986, pp. 39-60.

Volent, Paula. "Contemporary Techniques of Mounting Paper to Canvas." The Paper Conservator 10, 1986, pp. 18-23.

History of this Page

This page was created in April 2025 by Sandrine Blais from the BPG Support Problems page.