Holding the art: hinges, corners, spacers and backing

The attachment is the decision that can least be undone. This chapter separates the two methods every publisher sanctions from the ones they all refuse, and builds the back of the package so nothing touches what it should not.

1. What every publisher agrees on Understand

This is the one part of the subject where the sources line up. A national library, a preservation center, a conservation institute, a federal leaflet, the national archives, a conservation center, a state archives and the conservators' own professional wiki all state the same four things.

• The object is attached to the back mat, not to the reverse of the window. A preservation center gives the reason: an object attached to the window mat is in danger of tearing or skinning during future unframing.
• It is never glued down flat across its whole area, and under no circumstances adhered directly to the board.
• No pressure-sensitive or self-adhesive tape touches it. The professional wiki's sentence is the flattest in the research: tape should never be applied to the paper object when matting and framing.
• Two attachments are sanctioned: Japanese mulberry paper hinges with cooked wheat starch paste, and non-adhesive corners or edge strips.

Behind all four is one physical fact. Physical principle Paper takes up and gives off moisture, and it changes size when it does. A federal leaflet makes it a criterion: the attachment must allow the paper to expand and contract with relative humidity without creasing, cockling or tearing. A sheet fixed down at its edges has nowhere to go, and the buckling people blame on the framer is usually the sheet solving that problem the only way it can.

A national library's preference order is worth memorizing, because it is the shortest version of this whole chapter: non-adhesive methods wherever possible, which means photo or mounting corners, polyethylene strapping or mounting strips; otherwise Japanese tissue hinges with refined wheat starch paste.

2. Hinges, and the rule most readers have not heard

A hinge is a small tab of Japanese paper, adhered to the back of the object along its top edge and to the back mat, so the piece hangs from its top and is free to move everywhere else.

The rule. The UK trade specification states it in a sentence worth reading twice: hinges must be weaker than or similar in weight to the artwork, so that under duress the hinge will fail before damaging the artwork. A conservation institute says the same thing: hinges should not be heavier or stronger than the work itself. The hinge is a deliberate weak point. If something snags the frame, you want the tab to tear, not the paper.

The proportions. A professional wiki gives two rules of thumb: attach about a third of the hinge to the object and two thirds to the backing, and keep hinges away from the corners, roughly half a hinge width in, because a hinge at the corner hampers rotation and the corner can be caught. A conservation institute adds that hinge tabs should not be narrower than 1.5 cm, that most works need two hinges and larger works need more, and that a gap equal to the paper's thickness but not exceeding 2 mm should be left between the top of the object and the cut edge of the cross tab so the matted object can be lifted freely.

How many. A federal leaflet is specific: small objects need two hinges; for larger objects, a series of three to five smaller hinges is better than two wide ones, because the object can expand and contract between the hinges without cockling or tearing. A conservation center gives a spacing instead, saying that as a general rule hinges should be attached to the artifact five inches apart. The professional wiki notes that the old preference for as few hinges as possible has been modified because of center sagging and corner draping on very large or very thin papers.

Side and bottom hinges. The wiki is careful here: side hinges do not adequately support the object against downward pull and are used as restraining hinges, and are recommended for objects over 16 by 20 inches to prevent slippage in storage. Most conservators continue to recommend loosely adhered bottom hinges to restrain the bottom edge from drifting toward the glazing. Where side or bottom hinges are used, their location should be noted on the back mat.

The paper and the paste. Long-fibered Japanese tissue, water-torn rather than cut so the edges taper and the fibers tease out; a federal leaflet gives the fold-by-fold version and says paste is applied along the bottom quarter to half inch of the hinge. Cooked wheat or rice starch pastes are the preferred adhesives, are reversible, must be prepared fresh every few days, and should not have anti-fungal or buffering additives, which the wiki says may discolor objects as they age. Methyl cellulose stays on the paper surface rather than soaking in, which allows cleaner removal, though the wiki notes its strength of adhesion over time is not proven and is particularly questionable on acidic paper. Commercial heat-set and acrylic-dispersion hinge preparations are generally not recommended for long-term hinging, because formulations can change without notice and acrylic dispersions are not completely or easily reversible.

A conservation institute adds two cautions worth carrying into a shop: not all Japanese papers are conservation quality, since some contain a large proportion of wood pulp, so check the fiber content with the supplier; and commercially available gummed and pressure-sensitive tapes are often made of inappropriate materials with poor aging properties, will cause staining and damage, and may be difficult to remove.

3. Corners and strips

If you are going to do one of these methods at home, do this one. A federal leaflet names the advantage: mounting corners are simple to make and use and require no application of adhesive to the paper object.

The corners are folded from strips of unbuffered alpha-cellulose paper, and the leaflet explains why unbuffered: although buffered paper is often used with museum objects, certain photographic materials, especially certain color dyes, may be chemically unstable in contact with highly alkaline paper. Three adhesives are acceptable for fixing the corner to the mount, and the leaflet puts the condition in italics of its own: a specified double-sided tape, cooked wheat starch paste, or a white glue emulsion, with the adhesive only ever contacting the mounting corner and never the object.

Corners should be large enough to support the object but not so large as to be visually intrusive, and the leaflet says not to use them if the object is not strong enough or if its corners might be bent or damaged by them. A professional wiki adds that corners developed by the national archives are an improvement over the simpler construction, which has been observed to slip, and that unmounted albumen photographs cannot be safely photocornered because they simply sag.

Other non-adhesive systems in current use, from the same wiki: Callahan strips, Gillaland strips, radiant slings, support corners, Stieglitz corners, tabs, visible edge strips and Z-fold strips. A federal leaflet describes two more in detail: paper channel supports, folded strips of archival paper cut three to four inches longer than the object's horizontal dimension and taped to the board with about a sixteenth of an inch of space between the tape and the object; and polyester strip supports, laced through slits in the back mat and taped behind, snug but not taut.

The same leaflet is honest about where strips fail. Polyester strips are not suitable for friable media, polyethylene is better than polyester for very brittle objects because polyester can have sharp edges, and where strips cross the image, conservators have found the technique unsatisfactory for exhibition because differential fading can occur over extended display, from the plastic blocking light and reflecting light onto the adjacent surface. If a bowed object is mounted with polyester strips, do not attempt to flatten it by tightening them.

4. Dry mounting, and the materials to refuse

Dry mounting bonds a print to a board with heat and adhesive across its whole area. It produces a perfectly flat print and it is, in practice, permanent. A conservation institute states the position carefully: there is no evidence that dry mounting photographic prints causes the silver image to degrade, but dry mounting has the disadvantage of being, practically speaking, irreversible, and although manufacturers claim dry-mounted prints can be dismounted by reheating them in a press, that procedure is not safe for prints. A preservation center's household guide says dry mounting and spray mounting are often irreversible processes.

So dry mounting is a choice, made on purpose, for a piece you could replace. For anything else it is off the table. A federal leaflet puts it in its own list: do not laminate or dry or wet mount original photographs.

The materials every publisher refuses. Four of them appear on every list in this research.

Foam board is the live disagreement, and this manual gives a default. Two conservation-institute notes list paper-faced polystyrene foam board among the backing boards to use. A preservation center says flatly not to use any type of foam board, naming the paper-faced kind, boards sold as archival, a rigid faced board and expanded PVC, and adding that these are used in the majority of frame shops. The professional wiki supplies the mechanism that reconciles them: paper-faced versions have been observed to yellow over a few months from degradation of the polystyrene core, and the same off-gassing presumably occurs in the plastic-faced version where the facing does not show it, so these boards are not recommended for permanent contact with valuable objects but may be used as an additional backing for framed objects in travel.

Our default: no foam board in contact with an object; acceptable as an outer backing. That is the wiki's position, and it explains the other two rather than simply contradicting them.

5. Spacers, backing and the sealed package

Spacers hold the glazing off the art where there is no mat, or add to what a mat gives. A conservation institute describes strips of acid-free matboard attached to the rabbet with double-sided tape, or proprietary polyester and acrylic strips. A preservation center asks for them to be arranged post-and-lintel, the top piece resting above the sides and the bottom piece below, so that no piece can fall onto the object if its attachment fails; a professional wiki says ragboard is preferred as a stable material. The same institute is honest about the limits: a spacer may not be deep enough for an unstable artifact, friable images, cracked or flaking gouache, or cockled supports, and risks pigment transfer or partial adhesion, so spacers are only recommended for flat, stable works of art.

Backing boards, what to use. A conservation institute lists acid-free 100 percent rag matboard in four-ply, extruded twinwall polypropylene, and paper-faced polystyrene foam board. A preservation center lists Coroplast, archival corrugated board, 100 percent cotton honeycomb board and an aluminum-and-polyethylene laminate, and rules the foam boards out. A professional wiki adds candid notes on each: acid-free corrugated board has been observed in uncontrolled environments to expand more than non-acid-free cardboard, in one case pushing a 30 by 40 inch framed piece away from the wall as the backing swelled; honeycomb panels give dimensional stability for large or heavy objects; the aluminum laminate is very dimensionally stable and good for artwork that must not bend or flex.

Sealing: the one real disagreement, and this manual's default. Two conservation-institute notes tell you to seal the frame by taping across the join where the backing board meets the frame, preferring gummed linen tape over brown kraft because it is more stable, specifically to keep out dust and airborne pollutants. The professional wiki says the opposite about the frame: sealing the back and edges with a foil or heavy polyester vapor barrier is not recommended, because it can backfire, trapping humidity inside or slowing its release outward if moisture has entered from the front, and the safer solution is a sealed package inserted into the frame.

Our default: seal the package, not the frame. The publishers do not actually disagree about dust; they disagree about whether a frame should be made into a vapor barrier, and the answer that survives is to build the sealed unit separately and drop it into the frame. The wiki describes the construction: glazing at the front, the matted work, acid-free backing materials, polyester film at the reverse, edges sealed with polyester film tape, with acid-free paper placed around the edges before taping so the adhesive sticks only to the glazing and the film and never to the mat. A preservation center and a conservation center both describe the same unit.

What a sealed package is for, in their words: it buffers the work from drastic fluctuations in temperature and humidity and from airborne pollutants and dust, and a conservation center adds protection against improper handling. What nobody publishes is how long it holds relative humidity in an ordinary house. One note offers many weeks to years for a glazed and sealed painting, depending on the glazing, the backing board, the sealing materials and whether there are cracks or leaks; nothing equivalent exists for paper, and three publishers describe the benefit only qualitatively. Ask the authority

The dust cover and the label. A paper or spunbonded cover across the back keeps dust out of the frame's own cavity. The trade specification asks for a label with the date and the framer's name, and for existing labels to be preserved, since they can provide provenance. Write your own date on the back of anything you assemble. In twenty years it will be the most useful thing in the frame.

6. Textiles and objects

A textile is not hinged. It is stitched, by hand, to a rigid support covered with washed fabric, and the stitching is what holds it.

A conservation institute's note says its materials and methods apply to flat textiles in museum collections as well as to contemporary needlework intended for home display, which makes it the rare conservation document written partly for a household. The method: a thin layer of needlefelted polyester batting attached around the perimeter of a rigid support, prewashed fabric over it, and the textile stitched to the fabric with a fine needle and colorfast thread. Stitch choice follows the edge: herringbone for frayed edges, blind stitch for hemmed edges, running or whipstitches for plain edges, with weak areas secured by a self-couching stitch. Pins used to position the textile go between the threads, not through them. The test for whether the stitching is adequate is simple: held vertically, the textile should stay in position and not form puckers.

Its "never" list for things in direct contact with a textile is the bluntest in the research: acidic papers, cards and matboards; unsealed wood and wood products; colored materials that are not waterfast; glues, adhesive tapes and adhesive-coated boards; sprays of any kind, including relaxant and protective sprays and insecticides; and staples, tacks and nails. The same note explains why the traditional method failed: samplers tacked to a wood board got holes and uneven tension, staining as the tacks corroded, acid and resin exposure from the wood, and, mounted on stretchers, acted as an air filter trapping airborne dirt.

Spacers matter more here than anywhere: the institute says they stop the glazing crushing the three-dimensional quality of embroidery and reduce the risk of moisture condensing on the glazing, which could cause tidelines or mold. And it gives the referral line plainly: a textile showing fugitive dyes, mold, insect attack, powdering threads, stains, adhesive residues, splits, tears or losses, or one glued to acidic card, goes to a professional conservator before framing.

Objects in a box. Nothing in this research covers a household shadow box of three-dimensional objects. One institute covers flat textiles stitched to a covered support and stops there; a trade qualification examines three-dimensional memorabilia framed with frame extensions, but publishes no method. The trade specification's own line for objects is that the support must be reversible, with no adhesive or silicone. Treat an object box as a framer's job, and ask one question: how is the object held, and could it be taken out again? Ask the authority

8. See it See it

• Making mounting corners for photographs and paper objects, a federal leaflet: the one mounting method a household can execute correctly, fold by fold, with the reason corners must be unbuffered.
• Matting and framing, the conservators' own professional wiki: hinge proportions and placement, the adhesives weighed one by one, the sealed package, sink mats and the historical techniques.
• Exhibit mounting variations for objects on paper, a federal leaflet: four non-adhesive methods with their suitability limits stated honestly.
• Conservation framing of embroideries and other flat textiles, a conservation institute: the stitched mount, the never-use list, and when a textile goes to a conservator.

9. Practice Practice

Minimum: one piece with an attachment chosen and written down, and the package checked for forbidden materials. Time: about 45 minutes, including practice folds. Materials: a few sheets of plain acid-free paper for practice corners, scissors, a bone folder or the back of a spoon, and a sheet of scrap paper the size of your piece.

1. Fold four practice corners. Use half-inch strips of plain paper and the federal leaflet's pattern, and mount your scrap sheet in them on a piece of board. Lift it out and put it back twice.
2. Decide the attachment per piece and write it in the framing plan. Corners, strips, hinges, stitched to a support, or dry mounted on purpose.
3. Audit the package. List everything that will be inside the frame and check each item against the refuse list. If anything is hardboard, kraft corrugated, raw wood or colored paper over groundwood, replace it.
4. Decide the sealing question and write the answer. Sealed package, or not sealed, and why. Both are defensible; a blank is not.
5. If you are hinging (Go deeper; optional). Practice water-tearing Japanese tissue on scrap, and practice the T-hinge on a piece of paper you do not care about, as every publisher that describes the method tells you to.

10. Your pictures Your pictures

11. Check your work Check your work

Criteria

• The attachment is named per piece, and it is one you could undo.
• The object is attached to the back mat, not to the window mat.
• No tape touches the object, including tape sold as archival.
• Nothing in the package is hardboard, kraft corrugated, raw wood or colored paper over groundwood, and no foam board touches the object.
• The sealing question has an answer, and the back has a date on it.

Worked example

Hal Brewer's watercolor (fictional) comes back from the conservator with the old cloth tape removed and a note. The framer proposes: cotton rag back mat, two T-hinges of long-fibered Japanese tissue with cooked wheat starch paste along the top edge, placed about half a hinge width in from each corner, with a loosely adhered bottom hinge to restrain the bottom edge from drifting toward the glazing. No side hinges, because the sheet is 11 by 14 and under the 16 by 20 threshold the wiki gives. Backing: four-ply rag plus an outer corrugated plastic board. Sealed package rather than a sealed frame. A label on the back with the date, the materials and the conservator's name. Hal writes all of it in the plan before signing, which is what makes it a specification rather than a conversation.

Common mistakes

• Hinging to the window mat. Common in old frames and the reason so many sheets tear at the top edge when unframed.
• Using tape because it is sold as archival. The professional wiki's rule is about the object, not about the tape's quality: no tape on the object, and that includes the good ones.
• Making the hinge strong. A hinge is meant to be the weak point, so that under duress it fails before the artwork does.
• Two wide hinges on a big sheet. A federal leaflet asks for three to five smaller ones instead, so the sheet can move between them.
• Sealing the frame. Seal the package and drop it in; the professional wiki explains what sealing the frame can trap.
• Putting foam board against the object because it was sold as archival. The yellowing is in the core.

What is still unresolved

• Which level of framing these choices add up to: The levels.
• Whether you or a shop should do the work: A framer or yourself.
• What the package depth becomes once the spacer and backing are in: the depth box.
• How to check the attachment is still sound in a few years: The yearly check.

12. Knowledge check and scenario

Checklist

• One reversible attachment named per piece in the framing plan.
• No tape of any kind touching the object.
• Package audited: no hardboard, kraft corrugated, raw wood or colored paper over groundwood, and no foam board against the object.
• The sealing question answered either way, and a dated label on the back.
• Practice corners folded and tested before touching the real piece. (Go deeper; optional)