Ten thousand logos, drawn by one hand since 1988, and a large proportion of them cannot be read by anybody who does not already know the name. That is one designer's own estimate of his output, and it is the single most useful number in this argument, because it proves the illegibility is not an accident of one band's taste. It is an industry, with a supply chain, a price list and a waiting time.
The usual explanation is that the bands cannot draw and do not care. The usual explanation is wrong in both halves. The lettering is drawn with more deliberation than almost anything else in the genre, and the man who has drawn the most of it says openly that his own preference runs the other way.
Metal spent twenty years being legible
Nothing about metal lettering was hostile at the start. Keith MacMillan, signing himself Marcus Keef, put Black Sabbath on their 1970 debut and on Paranoid in white on black with a gothic weight to it, and the association between blackletter and heavy music dates from Sabbath Bloody Sabbath in 1973. Ray Hollingsworth cut the Iron Maiden wordmark at a London art studio in September 1977, geometric capitals with the tails sliced off on the diagonal. Joe Petagno drew Snaggletooth for Motörhead the same year in India ink and gouache, over a wordmark in the manner of Fette Fraktur, to which Lemmy Kilmister added an umlaut for the stated reason that it looked mean. James Hetfield drew the Metallica logo himself while still at school. Blake Edwards laid down the base of the Slayer logo in 1981 and Steven Craig Larned finished the version that went on Show No Mercy in 1983.
Every one of those is aggressive and every one of those can be read at four metres in a record shop, which is what they were for. The commercial logic is not subtle. A logo is a shop sign, the shop sign has to work at distance, and the whole apparatus of corpse paint, sleeves and lettering that black metal later assembled was built by people who had grown up looking at exactly these signs and had decided to do the opposite.
The break happened in about four years

Between roughly 1990 and 1994 the Norwegian bands and the people drawing for them replaced the shop sign with something closer to a seal. Darkthrone, Mayhem and Burzum all carried hand drawn forms that abandon the horizontal reading order, and the Emperor logo Christophe Szpajdel produced in 1992 is the textbook case: the first and last letters enlarged and fanned outward like wings, the serifs extended into branches, the branches ending in barbs that interlock across the centre line until the whole word balances as a single symmetrical object.
Symmetry is the mechanism, and it is worth stating precisely because it explains why these things resist reading rather than merely looking difficult. Latin script is read left to right, one letter at a time, and legibility depends on each letter being distinguishable from its neighbours. A bilaterally symmetrical device asks the eye to take the whole shape at once, as a coat of arms or a rune is taken. The letters stop being letters and become strokes inside an emblem. Nothing is obscured by dirt or by clumsiness. The reading order itself has been removed, and once it is gone no amount of squinting brings it back.
The ornament comes from a specific place too. Szpajdel names art nouveau and art deco, Victor Horta and Hector Guimard and Klimt, and once that is pointed out the resemblance is hard to unsee: the same vegetal line, the same insistence on filling the frame, the same refusal to leave a straight edge alone. Norwegian black metal in 1993 was working with the ironwork vocabulary of a Belgian metro entrance from 1900, which is a stranger inheritance than the forests and the frost ever were. The same thing happened to the painted face a few years earlier, and the argument over who did that first is set out in corpse Paint vs KISS.
The photocopier had a vote
The material conditions rewarded exactly this. Nothing in the underground of 1991 reached anybody through a printed sleeve first. It reached them as a demo cover run off on a photocopier, as a fanzine page, as an advertisement two centimetres square in the back of somebody else's zine, and every one of those channels destroys fine detail and keeps heavy black shapes. High contrast survives the machine. Grey does not. A logo built out of thick interlocking strokes still reads as itself after four generations of copying, and it reads as itself at the size of a postage stamp, which is where most people first saw it.
That is a design constraint doing exactly what design constraints do, and it does not contradict the ideological account. A form can be chosen because it excludes outsiders and kept because it photocopies well. Both were true at once, and the second is the reason the style spread through the tape trading network faster than any record could have carried it.
The man who draws them wants them readable
A logo everyone can read is a shop sign. A logo only the initiated can read is a door, and the point of a door is that it is shut.
Eirik Solvang, KaosMetal
Here the argument turns, and it turns against the romantic version. Speaking to the type foundry Blaze in March 2023, Szpajdel said plainly that he likes simplicity in a logo and likes them to be immediately legible, and that symmetry is something he was drawn to long before any of the commissions and simply lets happen. He has also described taking briefs from bands who ask, in as many words, for something black metal as fuck, and delivering designs at the far end of unreadable because that is what was ordered.
So the illegibility is demand side. It is not the aesthetic of the person holding the pen; it is the specification handed to him by hundreds of bands who understand precisely what the shape is for. A band commissioning a logo nobody can read is buying a filter, and it is paying a deposit for it. The person who ends up with the reputation for unreadable lettering is the one who has spent thirty years telling clients they could have something clearer, and the wider account of that career is in christophe Szpajdel, the Lord of the Logos.
What happens when somebody makes a readable one
The strongest evidence that the convention is a live rule is what occurs when a band breaks it. Deafheaven released Sunbather through Deathwish on 11 June 2013 with a cover of pink and orange and a plain block wordmark, the lettering borrowed from a Pulp sleeve of 2001, designed by Nick Steinhardt. The record went to number one hundred and thirty on the Billboard 200, took a Metacritic average of 92 from eighteen reviews and finished the year as the best reviewed album in any genre on that site.
A band commissioning a logo nobody can read is buying a filter, and it is paying a deposit for it.
The arguments that followed were not really about the music. A readable wordmark on a pink sleeve is a claim about who the record is addressed to, and the claim was understood correctly by everybody who objected to it. That is the proof the convention works. You cannot break a rule that nobody is enforcing, and thirty years after the first barbed capitals went onto a photocopied demo cover the enforcement is still in place. For the records and the scene the lettering was built to guard, start at the introduction.