Nineteen eighty six was the explosion. Nineteen eighty eight is the year the genre worked out what it wanted to be when it grew up, and the answer turned out to be longer, more elaborate, more expensive and considerably less fast.
It produced some of the best records in this history and it also contains, visible in retrospect, every reason the whole thing would come apart three years later.
What came out

Metallica's ...And Justice for All, nine minutes a song, in multiple movements, with almost no audible bass, reaching number six on the American chart. Slayer's South of Heaven, on which the band deliberately slowed down after deciding they could not go faster.

Testament's The New Order, Death Angel's Frolic Through the Park, Vio-lence's Eternal Nightmare, Forbidden's Forbidden Evil, Sepultura's Beneath the Remains sessions, Voivod's Dimension Hatross, Sabbat's History of a Time to Come, Deathrow's Deception Ignored, Watchtower's material and Coroner's Punishment for Decadence.
What changed since 1986
Three things, all of them consequences of the earlier peak.
Speed stopped being the question. Reign in Blood had settled it, so bands went looking for other problems: length, structure, harmonic interest, production. Slayer's response is the clearest of all, which was to slow down deliberately rather than attempt to outrun themselves.
Budgets rose. The majors had arrived, the records cost more, and the bands had time to think. That produced ambition and it also produced the first records in this genre that sound constructed rather than documented.
And the second wave arrived at full strength. Testament, Death Angel, Vio-lence, Forbidden and Heathen were all releasing serious records, which meant the founders were no longer competing only with each other.
The technical turn
Nineteen eighty eight is where thrash starts taking itself seriously as composition, and the results are magnificent and slightly worrying at the same time.
Watchtower were writing in time signatures that require concentration to count. Voivod were using chord shapes rock guitarists did not use. Coroner were treating a thrash album as a compositional problem. Deathrow had gone from crude to progressive in three years.
The worry is what technicality does to a music whose founding virtue was urgency. Once the question becomes how well can we play this rather than how hard can we hit it, some of what made the genre dangerous does not survive the change, and it also raises the barrier to entry. A teenager in 1984 could form a thrash band after six months of practice; a teenager in 1989 was looking at Watchtower.
| Album | Band | What it represents |
|---|---|---|
| ...And Justice for All | Metallica | Maximum ambition, minimum bass |
| South of Heaven | Slayer | Refusing to repeat themselves |
| The New Order | Testament | The second wave at full strength |
| Eternal Nightmare | Vio-lence | The Bay Area still angry |
| Forbidden Evil | Forbidden | Technique in the second rank |
| Dimension Hatross | Voivod | A private universe, fully built |
| History of a Time to Come | Sabbat | Literacy |
| Deception Ignored | Deathrow | Germany goes progressive |
The video that changed everything
Metallica had refused to make videos for six years on the grounds that the format belonged to bands who needed help. In 1988 they made one, for a nine minute song about a soldier who has lost his limbs and his senses, using footage from a 1971 film.
It went into heavy rotation and put thrash metal in front of an audience that had never gone looking for it. Within two years the genre was playing arenas, and within three the same mechanism that had delivered that audience was delivering it to somebody else.
What was already wrong
Three things are visible in 1988 with hindsight and were invisible at the time.
The records had started to sound constructed. Compare the flat wallop of 1983 with the vast, brittle, bass free architecture of ...And Justice for All: each step is a technical improvement and the cumulative effect is a band moving away from what it was.
Death metal existed and was taking the extreme audience. Everything thrash had promised was being delivered harder by people the same age as the listeners.
And the founding bands were now on major labels with expectations attached, which is a debt that comes due in the year the fashion changes.
The wing that took the technical turn furthest has a piece of its own in Technical Thrash Metal, and the full account of the run is in The Golden Years.
The production argument
Nineteen eighty eight is the year the genre's production philosophy split, and the two poles are on the two biggest records of the year.
Metallica went for scale: a vast, dry, brittle architecture with quadrupled guitars and, famously, almost no audible bass. It is technically ambitious and it is exhausting to listen to, and the argument about why the bass is missing has now run for thirty seven years.
Slayer went the other way. South of Heaven is slower, heavier and considerably warmer than Reign in Blood, with reverb allowed back in and the songs given room. It was received badly at the time by an audience who wanted the previous record again, and it is now widely regarded as one of their best.
Both decisions came from the same place, which is that a band with a budget and time will use them, and the interesting question is what each one bought.
The second wave takes over
The other thing 1988 settles is generational. By the end of the year the most exciting records in the Bay Area were being made by bands who had been in the audience in 1984.
Testament, Vio-lence, Forbidden, Death Angel and Heathen were all releasing serious albums, all had members in their early twenties, and all were playing to the crowds their predecessors had built. The founders had moved to major labels and to arenas, and the clubs had a new set of bands in them.
That is what a healthy scene looks like, and it is worth noting because it happened exactly once. By 1991 there was no third wave, because the young musicians who would have formed it were forming death metal bands instead.
Sources and notes
Release dates refer to original pressings. The American chart position for ...And Justice for All is its Billboard 200 peak.