Glossary of Terms Used in Picture Framing

Please find below a selection of definitions which are often used in conjunction with picture framing.

Acid-free: Most newer mats in picture framing are, in fact, acid-free. This term usually refers to materials such as boards and papers with a pH reading of 7, or extremely close. These materials are certainly more permanent and unlikely to discolour over time.

Acid migration: In picture framing this can occur when acidic papers or boards come into contact with acid-free artwork, thus staining it and causing a degree of damage. This contamination happens due to the transfer of acid from one material to another.

Acrylic: Sheets of this form of plastic are used extensively for glazing in picture frames. Acrylic sheets are clear and durable in nature, with a strong resistance to sunlight and exposure to other elements. Popular makes of acrylic sheeting used in picture framing include Plexiglas and Perspex.

Adhesive: Adhesive strips and boards are widely used in picture framing. This substance can bond or glue different types of materials together through either chemical or mechanical action, or a combination of the two. Some adhesives require activation by water, heat or various other means.

ATG Tapes: These tapes are double-sided and predominantly used to bond mat boards and other materials together. ATG tapes are often used with an adhesive applicator or transfer gun.

Auxiliary support: When it is discussed in relation to picture framing, this refers to the structure to which the support is attached, e.g. a wooden stretcher for oil paintings.

Backboard: This part is made from a solid piece of mat board and provides support to protect artwork on paper.

Backing Board: Not to be confused with a backboard, this protective sheet of cardboard, MDF or plywood is usually attached to the back of a picture frame. However, it can also be applied direct to the stretcher, to isolate the back of the support. Many other types of materials are used, such as foamboards with an acid-free rating to ensure the artwork is not damaged, or becomes more acidic over time. A customer can discuss the quality of backing used when deciding on the picture framing work to be done, and the value of the artwork to be framed.

Bevelled edge: This refers to the rectangular openings cut for picture frame mounts from matboard, at a 45-degree oblique angle, allowing for about 3mm of the core to be seen. You can also get a reverse bevel where the core will not be seen from the front.

Chemical deterioration: This happens due to chemical changes within a substance, or through the transfer of chemicals from a different source affecting the substance.

Conservation mounting: This form of conservation-approved mounting can help to prolong the life of artwork and photographic prints in picture framing. Acid-free materials are used in this process.

Conservation picture framing: This form of picture framing covers all the numerous methods that can be employed to protect and preserve artwork using conservation materials. In picture framing, these practices and techniques are commonly used by professional picture framers on the items being framed. These framing methods can ensure that the artwork is protected and preserved with as little deterioration to the piece as possible. The process is also applied to enable any changes to be made safely to the frame in the future. This is similar to museum framing in that as well as ensuring the artwork is beautifully framed, it is also protected against the effects of external factors such as acids or sunlight that can fade and damage the piece. The conservation materials used by picture framers are specially selected to ensure that all items to be framed are stable and will last a long time. This is the case during every stage of the framing process including the matting, hinging, sealing and glazing of the picture frame. These techniques are especially crucial when dealing with articles that require extra care due to the personal or financial value placed on them. Therefore, the conservation and preservation of these pictures is even more important in order to stand the test of time.

Corner rounder: This device can be used to round the corners of paper mountboard and sheets made of polyester.

Corflute: This is a brand name for a synthetic, corrugated plastic material which can be used as a backing board for picture frames.

D-rings: This is a very secure hanging device to keep a picture frame in place. The D-ring comprises of metal straps secured as a D-shaped ring using screws.

Deacidification: This refers to the chemical treatment of counteracting acid with an alkaline buffer in picture framing. The deacidification of a material such as paper may not be able to restore the piece, but can be used to prevent any further erosion.

Encapsulation: This is a form of protective enclosure for flat objects such as paper. It can be achieved by placing an item in between sheets of transparent polyester film, with the edges sealed. This serves to physically support and protect the item from the atmosphere, although it will not fully prevent it from deterioration within the capsule.

Enclosures: An enclosure is a general term used to describe a number of different protective container types used to wrap and mount items such as pictures.

Fading: Most forms of light will fade a picture, especially daylight and UV rays. The regular, clear float glass used for picture framing can normally block about 60% of the UV light, yet this can still lead to the fast fading of colours. To protect your artwork further from UV light, you can discuss the use of UV filtering glass when getting it framed as it can block over 97% of the rays but does cost more.

Friable media: This refers to the powdery materials used in creating artwork where the binding agent may not be strong enough to hold it to the supports, and being prone to crumble, for example, pastels and charcoal.

Glazing: Sometimes clients may wish to have their pictures glazed directly onto the artwork without the need for any mats, mounts or spacers. This may save on costs but is not advisable as it may impact on the artwork negatively, with discolouration, the forming of condensation or the item sticking to the glass becoming more likely. Therefore, to avoid this happening, it is always suggested you frame the artwork with a mat or mount. If the piece is especially large, you can also place plastic strips known as spacers in between the glazing and the artwork, under the lip of the frame.

Hinge: This flexible paper strip can be used to attach a piece of artwork to a mat along one edge. Generally produced from Japanese paper, the hinge allows the artwork to be lifted for inspection of its verso.
Japanese paper: As explained in the “Hinge” description, this form of strong paper, usually made from long-fibred stock such as Mulberry, is well-known for its flexibility and strength. This is why this material made in Japan is widely used as a long-lasting solution for lining and reinforcing paper, making for an excellent hinge.

Keys: When related to picture framing, these small, wedge-shaped sections of wood can be inserted into the corner of the stretcher enabling its dimensions to be increased.

Matboard: The American term for mountboard, it refers to the coloured cardboard used right under the glass of a picture that has been framed and surrounding the image. There are generally three main categories of matboard: regular, museum and conservation. These are named according to their quality and can vary according to the picture framing job in hand. A fine art or watercolour piece may require the conservation or museum quality board, which are both acid-free, with fade-resistant colours and therefore will not damage the artwork.

Mildew: This is caused by fungi species which thrive on dark, damp and humid areas, and can leave brown spots on any paper-based artwork. When watercolours are used, it can leave dark spots on the painting. The activities of fungi can seriously damage the fibres on paper and canvas, while can also leave matboards with a degree of discolouration and other related problems. It is extremely hard to reverse any effects of mildew on a piece of artwork, so it is important to store it in a place with 50% relative humidity and ideally at 70 degrees Fahrenheit.

Mounting: This is the process of attaching the work to a supportive surface known as a mount or mat. This can be done either before framing or as a standalone protective enclosure.

Mounts / Mats: This is made from two pieces of mat board, taped together along the edge to allow it to hinge open. The item to be mounted, be it a paper or photographic print, is hinged on to the backboard of the supporting mount. The top board, or window mount, has an opening cut which frames the artwork. The mount or mat will protect the artwork from physical damage, while acid-free mounts will also protect the item from chemical damage. This is why it is important to select a mount that is right for the artwork being framed.

Non-buffered: This term is used to describe materials which do not contain alkaline buffers which are frequently added to neutralise acids. Non-buffered materials are recommended for items such as colour photographs where alkaline buffering may adversely affect the piece. In other instances, buffering is necessary in order to neutralise the acids in papers and boards and protect the artwork.

Paper: This hand or machine-made material is produced using predominantly cellulose fibres formed into matted or felted sheets. Most modern paper made today is produced from wood pulp, with the type of paper varying according to the treatment used, which affects its properties. Paper that is made using an alkaline process is generally more stable than paper produced from an acidic method. Acidic paper can contain a high concentration of groundwood and the high lignin content means it is therefore much more unstable. Most traditionally-made Japanese papers utilise plant fibres as they can offer flexibility, strength and longevity.

Perspex: This is a well-known brand name for an optically clear, thermoplastic resin - polymethyl methacrylate. This material can be used as a substitute for glass in a number of applications, including picture framing. This product is widely used and similar to Plexiglas, another popular brand.

Photographic-quality mountboard: This mountboard does not contain any additives or elements which could be damaging to photographs. You can choose this type of mount or mat board when you need a mount that is both acid and sulphur-free.

Picture Framing: When you are choosing your picture frame, a professional framer will always give you the option as to the quality and type of materials to be used in the framing process. In the majority of cases, most artwork will not require the more expensive framing options, such as stable, non-harmful and acid-free materials of a conservation framing standard. If you have a commercial reproduction, print or poster printed on standard acidic paper, then you may wish to choose the cheaper framing options. The final decision is, of course, up to you.

Plexiglas: See Perspex above.

Preservation: This broad term involves any action taken to delay the deterioration of, or prevent damage to, cultural material. In order to preserve your artwork, the environment will need to be controlled, as much as possible. The preservation of artwork may include treatments to maintain the item in an unchanging state, or repairs to damaged materials. See also Restoration.

Pressure sensitive tape: This adhesive tape is often referred to as 'sticky tape'. The tape will adhere to a surface when sufficient pressure is applied. This tape is not usually recommended for use on original materials as the adhesive is prone to degradation, with a brown residue left which can stain and make the paper more brittle.

Reconstruction: This refers to any actions that are taken to recreate, either in whole or in part, a form of cultural material.

Restoration: The actions taken to modify the existing structure of an object and its materials to bring it back towards a representation of an earlier state. See also Preservation.

Ribloc: A brand name for a ribbed, lightweight material used for making rollers where un-stretched paintings can be stored.

Rollover edge: When framing a picture it refers to the canvas edge which is rolled over the auxiliary support. See also Tacking edge below.

Screw eye: A metal ring used as a hanging device on a picture frame with a screw fixed at one end of the frame.

Sealant: A paste or liquid coating that once hardens is used to form a seal against gas or liquid entry. A sealant can be used to reduce the porosity of an object, acting as form of barrier to outside influences.

Strainer: When used as a term in picture framing, a strainer is a wooden auxiliary support composed of at least four members on which a canvas is stretched. The corners of a strainer are not adjustable, as with a stretcher. See also Stretcher below.

Stretcher: In picture framing, this term describes a wooden auxiliary support constituting of at least four members on which a canvas is stretched. Unlike with a strainer, this has expandable corners allowing for its dimensions to be increased slightly when necessary. See also Strainer above.

Support: This can be any material acting as a base for, and supporting the image layer of, a piece of artwork. The type of support used can depend on the artwork; paper, glass and metals are often used for photography, with canvas and wood panels used to support paintings. See also Auxiliary support above.

Tacking edge: When framing a picture, the tacking edge is the edge of a canvas secured (or tacked on) to the auxiliary support. This is often achieved using staples nowadays.

UV radiation, ultraviolet radiation: A destructive range of radiation within the electromagnetic spectrum. Ultraviolet radiation is very close to the visible light spectrum, although its wavelength is shorter and it has a higher energy.

Varnish: This removable, outer layer of a painting is used to enhance its appearance and give it an added layer of protection. The varnish is often removed and replaced at various stages in the life of a painting.

Window mount: This refers to the upper board of a mount where a window is cut into it in order to provide a frame for the artwork. This form of mount allows you to handle the work without having to directly touch it. As well as keeping the glass or Perspex from direct contact with the work, a window mount can also enhance the visual presentation of the artwork. See also Mounts / Mats above.

Wet mounting: The process in ensuring a piece of artwork is kept permanently flat. Wet mounting involves gluing the artwork, such as a large poster or photo to a backing board sheet of cardboard, plywood or similar material. This is necessary as if the material is not kept flat, the appearance of the paper can tend to be affected. The unsightly waviness that can occur happens because the fibres of the paper expand and contract according to changes in temperature and humidity. The backing board is usually coated in PVA glue and with the poster or photo then pressed onto it. This method of mounting is relatively quick and easy to perform. However, wet mounting is only really suitable for inexpensive artwork as the process is permanent and non-reversible. If you have any valuable, rare or historical artwork to be mounted, then you should consider getting it conservation-framed.