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Matting and Hinging Works of Art on Paper

The following instructions primarily apply to the mats created at the Library of Congress for long-term storage as opposed to those created for temporary gallery display.


These instructions primarily apply to mats created at the Library of Congress for long-term storage as opposed to those created for temporary gallery display.

Most people are familiar with standard matting and framing concepts from exhibitions or having art framed for personal use. The instructions outlined in this guide cover matting and hinging techniques that are more complex than those used to create standard picture mats. These designs may be used in combination with wrappers or boxes or additional outer protection. It is important to remember that the quality of materials used in creating storage mats is of equal importance to the construction techniques.

A storage mat is used to house an object that requires protection beyond a paper folder or polyester sleeve due to the condition or fragility of its support material (i.e., paper) or media. Mats are often used to protect objects of higher value which are frequently handled for research or display. Mats can be useful for protecting items that have friable media on the surface or that are slightly curved or warped. Ideally, a mat should provide support and protection from damage during handling, while enhancing the aesthetic appeal of the item. Any relatively flat item can be matted artworks, manuscripts, printed materials, etc.

The preservation procedures described in this guide have been used by the Library of Congress in the care of its collections and are considered suitable by the Library as described; however, the Library will not be responsible for damage to your collection should damage result from the use of these procedures.

Some of the artwork shown in the examples are practice samples, not collection items. Citations are given when possible.

Standard Sizing

For Library staff: Unless otherwise requested by a division, LC mats are usually made to standardized sizes that match our boxes and folders: 

AA   11 x 14"
A    14 x 18"
B   20 x 24"
C   22 x 28"
D   28 x 40"
E   34.5 x 48" (or custom size by consultation)


The type of mat used will be based on the support needs of the item, the use expected, the storage environment (i.e. drawer, folder or box), and the wishes of the curator or collection manager.

  •  A standard window mat consists of two pieces of matboard cut to the same size, hinged together along the long edge, with a window cut out of the front piece. Usually, we will add a front sheet hinged on, called a wrapper in these instructions. This will protect the surface of the matted item from dust and light and provides a nice surface for labels.
  • A sink mat is essentially the same as the standard mat but adds a high, protective border around thick, friable, or warped art to protect it from having the window mat sit directly on the surface of the object.
  • A double-sided mat allows both sides of an object to be viewed by turning the mat over. Occasionally two related pieces will be mounted together in a mat back-to-back in this manner.
  • There are many variations for each of these general mat types. Examples can be found at the end of these instructions.


There are a great variety of ways to attach an object into a window mat. Our current practice favors non-adhesive means of attachment for many items. Edge strips or channels, corners, polyester half-moons, or polyester sheeting with ultrasonic dot or line welds offer a means of securing art without introducing adhesives directly onto the object and readily allow the object to be removed from the mat. Please see the Mounting & Hinging and Other Resources sections for more information about methods of attachment, including more traditional hinging.