Sludge metal (also known as sludge doom or simply sludge
The key characteristics of sludge metal are a slow tempo combined with down-tuned, heavily distorted guitars. Many sludge bands also make use of elements of industrial music, southern rock Drug addiction is a common theme, while discussion of poverty and pollution are also prevalent.
Sludge bands who lean more towards hardcore are sometimes called sludgecore by music historians including Garry Sharpe-Young and David Pearson. New Orleans is the birthplace of the sludgecore movement, with Eyehategod being this style's frontrunner.
History
thumb|left|The B-side of [[Black Flag (band)|Black Flag's featured some of the earliest sludge metal tracks]]
Since its inception in the late 1970s, the sound of hardcore punk was primarily defined by its high tempos. However, by the early-to-mid-1980s, a crop of bands, particularly California groups Black Flag, Fang and Flipper, began to play slower tempos as a way of antagonizing many in the scene. As early as 1982, Flipper's Album – Generic Flipper made use of dirgey, low tempos and expansive song lengths in the case of "(I Saw You) Shine", to create what, in his book Monolithic Undertow In Search of Sonic Oblivion, writer Harry Sword credited as the "genesis of sludge metal". Furthermore, Los Angeles band Saint Vitus, one of the forefront groups in the still emerging doom metal genre, released their self-titled debut album through SST Records in 1984. However, it was the three track B-side of Black Flag's My War (1984) and its embrace of Black Sabbath influence, that is generally accredited as beginning the sludge metal genre.
Early on My Wars influence took a particular hold on Seattle, Washington's burgeoning grunge scene, inspiring some of the scene's earliest bands like 10 Minute Warning and the U-Men. The Melvins, formed in Montesano, Washington in 1983, were one of the most prominent bands in the scene to embrace the influence of both My War and Album – Generic Flipper, and would go on to be described by publications such as Revolver as the band that "invented sludge". Beginning their career by playing hardcore, the band began playing "slow and heavy riffs" after seeing Black Flag in Seattle in 1984, to form a dirge-like music that inspired much of the subsequent sludge and grunge bands.
thumb|right|[[Eyehategod are one of the defining bands in the New Orleans sludge metal scene]]
By the 1990s, Louisiana developed one of the largest and most influential sludge metal scenes, with bands like Acid Bath, Crowbar and Eyehategod. Eyehategod were one of the first sludge bands to form in the state at a time when the majority of local bands were fast. The band purposefully rebelled against this, embracing the influence of Black Sabbath and Black Flag, as a means to antagonize their peers. In the following years, Eyehategod became one of the defining and most influential bands in the genre: their second album Take as Needed for Pain (1993), inspired a multitude of bands to form or change sounds; and Eyehategod's members would go on to be a part of other defining New Orleans sludge bands including Soilent Green, Crowbar and Down. In a 2009 interview with Decibel magazine, Down vocalist Phil Anselmo stated "Back in those days, everything in the underground was fast, fast, fast. It was the rule of the day...But when the Melvins came out with their first record, Gluey Porch Treatments, it really broke the mold, especially in New Orleans. People began to appreciate playing slower."
The 924 Gilman Street punk scene in Berkeley, California produced a sizeable sludge metal scene in the late 1980s and into the 1990s, which included Neurosis and Noothgrush. Neurosis' transition from playing hardcore to a droning, ambient and progressive style of sludge metal helped pioneer the post-metal genre, then joined by Boston's Isis and Umeå's Cult of Luna in the following years. while Boston's Grief did the same with anarcho-punk. In the United Kingdom, both Fudge Tunnel and Iron Monkey were prominent bands in the 1990s who embraced the influence of the Melvins and nascent sound of sludge. Damad's influence led to Savannah developing a significant sludge metal scene in the 2000s which included Baroness, Black Tusk and Kylesa. Bands in the scenes' equal parts influence from punk, metal and rock led to writers like J.J. Anselmi referencing a "Savannah sound". Baroness' progressive take on the style, which also incorporated elements alternative rock gained significant commercial success in the 2010s.