In this catalogue paintings are classified as follows:

Painting is a work with acrylic and/or oil on canvas or on another two-dimensional support (canvas board, wood panel, etc.)

Painting (mural) is a large-scale painting, historically called "mural"

Painting on paper describes a work in acrylic, oil or watercolor on paper or board

Dates

Lichtenstein usually signed and dated a painting on the verso around the time it was finished, inventoried or shipped to a gallery or storage. Some pre-Pop paintings were dated in code (e.g., RLCR 502). 

See also: 8. DATES

Media Lines

Described are all media visible on a painting's recto. Paint is listed first, followed by graphite pencil where present, followed by the support. An inscription's medium is given beneath the media line if different from the painting media.

Acrylic and Oil Paints

The painting media lines in this catalogue are rarely based on technical analysis by a museum or a conservator. They are mostly informed by conversations with the artist's studio assistants, by examination of paint jars and tubes that were kept after the artist's death and by RLF records or Leo Castelli Gallery files. 

In this catalogue, all types of acrylic paint are listed as "acrylic" and all types of oil paint as "oil."

Historically, the brand name "Magna" (acrylic dispersion paint by Bocour Artist Colors, Inc.) has been used to describe all of Lichtenstein's acrylic. RLF records and technical analysis by art museums confirm that the artist did not only use Magna, but at times Liquitex acrylic emulsion paint and, later, Golden Artist Colors acrylic dispersion paint. When Magna production stopped in c. 1990, Lichtenstein bought up large amounts of Magna. He also reached out to Golden who worked with him to devise custom MSA colors in Lichtenstein's hallmark hues.      

Pop paintings and later works were usually painted with both acrylic and oil. It is assumed that around 1962, Lichtenstein experimented with Liquitex and Magna before adopting Magna as the main medium. For paintings of 1962–63, media lines are informed by notes on RL Studio Cards and/or in the Leo Castelli Gallery inventory. In rare instances, media lines were written by the artist on the verso of a work (e.g., RLCR 691). For paintings of 1964 and beyond, solid colors are assumed to be acrylic and dots and diagonals oil. However, it is possible that Lichtenstein continued his experimentation with paints through and after 1964.

Graphite Pencil Underdrawing

A closer look at Lichtenstein's paintings reveals that graphite pencil underdrawing and palimpsest is visible in most of them, starting in the 1960s. Nevertheless, pencil has not historically been mentioned in the related media lines. Due to the artist's well-known intention that his work not appear "too finished," this catalogue includes pencil in media lines. If in question from examination report results or other documentation, the presence of graphite pencil is assumed. When a researcher's examination report confirms that pencil is not visible, it is not included. 

Painting: Other Mediums and Techniques

Canvas
Different types of canvas are not described. A regular type used was #10 cotton duck from New York Central Art Supply. Circular canvases were at least partially ordered there as well. Earlier paintings' canvases are typically finer and sometimes described as "linen" in studio records. 

Sand
In the Imperfect/Perfect and Entablature paintings, grainy areas are visible. Lichtenstein created this texture by adding beach sand, usually to a thick white underlayer over which he applied the final color. 

Sgraffito
This reductive technique of line-making is found in about 25 pre-Pop paintings. 

Stretchers
Stretchers are not included in media lines. Lebron stretchers were standard orders from c. 1972 on, and were typically delivered assembled. A different stretcher brand was introduced once and quickly abandoned.  

Strip frames
Strip frames are not included in media lines. Slightly raised above the edges, strip frames served as a practical protection during shipment and storage movements and were routinely added to paintings at least from the time James dePasquale became Lichtenstein's assistant.   

Painting on Paper: Other Mediums and Techniques

Masking out
Masking techniques are indicated, but the material used (e.g., frisket, small objects) is not identified (e.g., RLCR 219).

Watercolor application
When it is applied in multiple ways, watercolor application method is described, otherwise brush is implied. For example, see RLCR 365, “Watercolor, brushed, smudged by hand and sprayed, with masking out, graphite pencil on paper." 

Dimensions

Painting dimensions are given from canvas edge to canvas edge, excluding original wood strip frames nailed to the edges. 

For multi-panel paintings, if panels are joined, overall dimensions and dimensions of each canvas are given. If panels are separate, only panel dimensions are provided since overall dimensions vary by installation. Lichtenstein usually suggested a distance of approximately 7 inches between canvases for installation. This fact informed spacing of related images in the catalogue entries (e.g., RLCR 1635). 

See also: 10. DIMENSIONS

Signature, Inscriptions, Marks

The artist usually signed and dated his paintings on the canvas verso in charcoal and applied a spray fixative before sending it to a gallery or storage.  

Pre-Pop paintings are often signed or initialed on the recto in oil, or inscribed with the artist's name and other tombstone information on the stretcher or tacking margin. 

See also: 11. INSCRIPTIONS