Repairing comic books has been around in our hobby since the first comics were sold to the public. It is natural for people to want their books to look as new as possible or to remain intact so that they can continue to be read. Early in fandom history, simple and crude repairs were performed by the owner of the comic for these reasons. For example, a couple of pieces of tape were used to hold on the cover, a dab of Dad's wood glue was used to close a tear, some crayon made the cover look better, etc. As the hobby grew and comics became more expensive, the need to define and describe various repairs became apparent. Some repairs remained acceptable to collectors and were "grandfathered," such as tape. Most repairs, however, were defined as restoration.
Restoration can be broken down into two main types: treatments intended to prolong the existence of the comic book and treatments done for aesthetics. Both types of restoration involve the introduction of non-original material to create or facilitate a desired effect.
CGC defines restoration as treatments intended to return the comic book to a known or assumed state through the addition of non-original material. Examples of restoration include:
Color touch. Using pigment to hide color flecks, color flakes, and larger areas of missing color. Examples of pigments may include paint (acrylic, oil, watercolor, etc.), pencil crayon, pastel, pen, marker, white-out, etc. Color touch is sometimes called inpainting.
Pieces added (piece replacement). Added pieces to replace areas of missing paper. Piece replacement material can be non-original paper such as wood or cotton fiber papers, married from a donor comic book, or color-copied pieces. This process is sometimes called infilling.
Tear seals. Sealing a tear using an adhesive. An adhesive may be cellulose, chemical, or protein-based glues as well as anything that acts as an adhesive, such as saliva.
Spine split seals. Sealing a spine split using adhesive (adhesives are described above under "tear seals").
Reinforcement. A process by which a weak or split page or cover is reinforced with adhesive and reinforcement paper. Reinforcement papers are commonly wood or cotton fiber papers.
Cleaned (lightened). An aqueous process to lighten the paper color or remove soluble acids, often using chemical oxidation, solvents, or water. This process is sometimes called cleaned and pressed or C&P. Common chemicals used to lighten paper include benzene, acetone, xylene, sodium hypochlorite, hydrogen peroxide, chloramine-T, chlorine dioxide, sodium borohydrate, etc.
Re-glossed. Enhancing the cover gloss, typically through the application of canned re-glossing/art fixodent spray.
Non-additive processes such as dry cleaning (non-aqueous removal of dirt, soot, or other non-original surface material), pressing (removal or reduction of bends and creases), and tape removal, are not considered restoration by CGC. In accordance with hobby standards, the addition of tape is not considered restoration but will always be noted on the CGC label.
While we believe that tape should never be used on a comic book for any reason, our hobby has accepted that people used tape to keep comic books from falling apart. This measure was taken even before comics became collectibles. In the early days of fandom, some sellers stated that tape was not a defect and some collectors even accepted tape on mid grades. CGC will downgrade for tape, as we consider it a defect no matter why or when it was added.
Restoration has become a controversial issue in the comic book hobby because it is not always disclosed by sellers, but can dramatically affect the value of a comic book. CGC protects against this by ALWAYS disclosing detected restoration. In some cases, restoration is not readily detectible to novices or individuals lacking expertise in restoration detection. Even experienced hobbyists miss restoration when grading comic books. For this reason, CGC has made the restoration check a mandatory component of the CGC certification process..