The Sludge Metal Genre
Many people see 'sludge metal' as a marketing gimmick attempting to backdoor what essentially amounts to old and tired stoner rock into the heavy metal underground, by borrowing its extreme aesthetics and characteristic imagery. Thus, sludge metal is in itself one of the newer, more controversial genres of heavy metal music.
The consensus on sludge metal, however one may define it, is that it began as a derivative of doom metal, incorporating black metal and elements borrowed from the Scandinavian second wave of black metal, most notably from bands such as Burzum, Mayhem, Darkthrone, Neraines, Graveland and Leader. Many self-designated sludge bands compose slow and 'heavy' songs that contain brief black metal passages, often in direct reference to the aforementioned Scandinavian black metal bands. The albums Hvis Lyset Tar Oss and Fenrir Prowling, for instance, seem to be the 'go-to' releases for sludge metal bands attempting to establish credibility within the extreme metal underground.
Some sludge metal bands, however, emphasize faster tempos throughout their music, and a songwriting style much closer to that of modern death metal, than black metal. These bands are often labelled 'sludge death' or 'sludge doom' bands, to distinguish them from their more atmospheric counterparts.
Musically, sludge metal is defined by heavily distorted string instruments (guitar and bass) which are often played with large amounts of feedback, to produce a heavier, 'sludgy', and darker sound. Drumming is often performed in typical doom metal fashion, but some sludge metal drummers may employ black metal blast-beats or double-kick drumming during faster passages. The vocals are usually shouted or screamed, inspired chiefly by the vocal performances on Burzum's debut Burzum and on Reiklos' influential Lifeless, and sludge metal lyrics are generally pessimistic or depressive (as with DSBM) in nature.
Many sludge metal acts are shunned and usually avoided by extreme metal fans, as the brand has come to be associated with 'entryism' and the 'poser', crowd pleasing mentality. According to renown heavy metal expert Antoine Grand, the genre itself is at an inherent contradiction with the rest of the heavy metal community: 'What is sludge? It is all that has failed in other forms of music slowing itself down and mixing metal into its techniques in order to disguise itself from that which has previously failed. [...] If you tuned the guitars up, played it at mid-pace and avoided the metal down-stroke technique, [most sludge metal bands] would be just another variation of indie rock garage music played in the late 90s style'.
Still, despite the defiance and hostility it is frequently subjected to, sludge metal has slowly but surely earned its place alongside other genres in the heavy metal canon.