Detective fiction knows no metaphoric bounds today, but texts of the classic period make use of common kinds of imagery. The images per se vary, but they cluster around the opposition of hard versus soft, and smooth versus rough. This might seem obvious, but it has some history.
The terms "hard-boiled" and "soft-boiled" derive from American commonplaces about eggs. Now that they come in boxes from the store, eggs are less metaphorically central than they once were. Fifty years ago most Americans knew to the minute how long they wanted their breakfast eggs immersed in boiling water. A "two-minute egg" had a runny, liquefied yolk, while a "ten-minute egg" was solid throughout. The distinction between hard throughout and soft inside but hard outside was widely known. The "hard-boiled" was in opposition to the "brittle," for under the shell might be softness.
This imagery complimented another about sap. A people closer to nature, whose syrup came from maples, knew that "sap" was sticky stuff leaking from trees, which also had hard exteriors. The noun "sap" grew up after the Civil War and appears in Mark Twain's work ( "saphead") to refer to someone who is foolish, whose mental processes are not structured and contained. The verb "to sap" meant to hit someone over the head with a blackjack, causing the victim to become "soft." By the time it appeared in hard-boiled narrative, "sap" meant "sucker" or weak -- the opposite of "hard-boiled." Sap and soft-boiled correspond to sentiment, gratitude, and romantic love, which would weaken the hard-boiled hero/ine.
The contrast between the smooth and the rough is an extension of the distinction between the hard and the soft, with the added meaning of "modern" vs. "old-fashioned." During the classic hard-boiled period, the smooth was urged upon consumers in clothing (ready-made clothes instead of home-spun) in home appliances (gas and electric ovens, instead of coal stoves) and transportation (the automobile, instead of the horse). Protagonists of hard-boiled fiction tend to be clean-shaven, dress in smooth fabrics, drive cars, live in apartments (often efficiencies), and to use modern products. As I argue in The American Roman Noir, hardness and refusal to "play the sap" are usually synecdochal representions of the modern economy. 1
Chandler stands out as the great creator of imagery in the genre and one of the greatest in American literature. Philip Marlowe's world abounds in comparisons, giving the detective the complexion of a polymath. Chandler's metaphors are mostly similes. They most often describe a character memorably on first appearance, saving the author effort when the character reappears. Thus Carmen Sternwood in the first four pages of The Big Sleep walks "as if she were floating," has teeth "as shiny as porcelain," lowers her eyelashes like "a theatre curtain," sucks her thumb "like a baby with a comforter," and "went up the stairs like a deer" (2-4). The reader understands that she is infantile, transparently cunning, and energetic. "Artificial" seems to be the concept Chandler had in mind; he returns to it later in the novel: Carmen acts "as if [she had] artificial lips and had to be manipulated by springs" (147). A description such as the later reminds us of Victorian machinery – exposed and clumsy. Even here the author indirectly values the modern: that which is seamless, functional, and rhythmic. Chandler often uses similes in early descriptions of characters and then invokes them again later.
Chandler mined a few subjects for his metaphors, all of which can be seen contributing to his description of General Sternwood in The Big Sleep. Chandler's primary referents were time, mass, motion and inertia. The General "nodded, as if his neck were afraid of the weight of his head" (7). But Chandler also used California life and the daily culture of Los Angeles: The General's "few locks of white hair clung to his scalp, like wild flowers fighting for life on a bare rock" (6). Chandler was intensely conscious of death and disease: The General's orchids are "plants with nasty meaty fingers and stalks like the newly washed fingers of dead men" (5). Chandler spent his days at home writing, in a domestic, even kitchen-bound, existence: The General's greenhouse is like a "slow oven," where Marlowe feels "trussed like a turkey."
1 William Marling, The American Roman Noir, 39-92. See also William Marling Raymond Chandler. Boston: Twayne, 1986.