Sol Steinmetz, in "Yiddish and English: The Story of Yiddish in America", suggests that this figurative derivation of "schmaltz" does not exist in Yiddish. http://www.randomhouse.com/wotd/index.pperl?date=20010910
Schmaltz or schmalz is rendered pig, chicken, or goose fat used for frying or as a spread on bread, especially in German and Polish cuisine. The brown fatty residue left in the pan after frying bacon is schmalz (although the melted fat that is usually referred to as schmalz has a whitish color).
Schmaltz rendered from a chicken or goose is popular in Jewish cuisine; it was used by Northwestern and Eastern European Jews who were forbidden by kashrut (Jewish dietary laws) to fry their meats in butter or lard, the common forms of cooking fat in Europe, and who could not obtain the kinds of cooking oils, such as olive oil and sesame oil, that they had used in the Middle East and around the Mediterranean (as in Spain and Italy); the overfeeding of geese that Jews used to produce more fat per bird produced postclassical Europe's first foie gras as a side effect.
Besides Schweineschmalz (pig-schmalz, i.e. lard) the manufacture of schmalz can involve cutting the fatty tissues of a bird (chicken or goose) into small pieces, melting the fat, and collecting the drippings. Schmaltz may be prepared by a dry process where the pieces are cooked under low heat and stirred, gradually yielding their fat. A wet process also exists whereby the fat is melted by direct steam injection. The rendered schmaltz is then filtered and clarified.
Homemade Jewish-style schmaltz is made by cutting unsmoked chicken or goose fat into small pieces and melting in a pan over low-to-moderate heat, generally with onions. After the majority of the fat has been extracted, the melted fat is strained through a cheesecloth into a storage container. The remaining dark brown, crispy bits of skin and onion are known in Yiddish as gribenes.
Since the rendering process removes water and proteins from the fat, schmaltz does not spoil easily. It can even be used to preserve cooked meats if stored in an airtight container in a cool, dry location. This is similar to the French confit.
Schmaltz often has a strong aroma, and therefore is often used for hearty recipes such as stews or roasts. It is also used as a bread spread, where it is sometimes also salted, and generally this is done on whole-grain breads which have a strong flavor of their own.
A vegetarian (and consequently pareve) version of schmaltz was first marketed commercially in South Africa by Debra's under the slogan "Even the chicken can't tell the difference". http://www.astray.com/recipes/?show=Parve%20schmaltz. Other vegetarian brands include Nyafat. The taste and texture is similar to real chicken schmaltz but the saturated fat content is much lower - Debra's Schmaltz, for example, bears the South African Heart Foundation's http://www.heartfoundation.co.za/ sign of endorsement.
Etymology and other meanings of the wordshmalts is the Yiddish word for chicken fat, closely related to Modern German schmalz 'cooking fat', both from Middle High German smalz. It was brought to American English by Yiddish-speaking Jews who used this word mostly to refer to kosher poultry fat.
The expression "falling into the schmaltz pot" refers to the concept of having something good happen to you, often by sheer luck (e.g., being born into a good family).
In American English, schmaltz (adj. schmaltzy) has also an informal meaning of excessively sentimental or florid music or art or maudlin sentimentality. Its earliest usage in this sense dates to about 1950,; by 1935, it already meant 'straight' jazz. In the Montreal Jewish community, it is a slang term for money.
In the United States, schmaltz was also a technical term among sign-makers for roadside signs in which the design was made of large (1", 2" or larger) sequins that trembled and caught the light. Such signage was more common before lighted, neon, and retroreflective signs became common. Schmaltz signage almost completely dropped out of use by the late 1970s, but is still occasionally seen, especially to create a nostalgic feel.
schmaltz in German: Schmalz
schmaltz in Hebrew: שמאלץ
schmaltz in Japanese: シュマルツ
schmaltz in Polish: Smalec
schmaltz in Yiddish: שמאלץ