[dredmorbius]

Something had to bring the skin up to ignition point. That may very well have been hydrogen, either above or below explosive mixes.

Static electricity (from a potential difference with the ground, St. Elmo's fire, or other sources) likely also contributed. Forensic analysis strongly supports leaking hydrogen from the aft part of the airship, given the nose-high, tail-low attitude and handling difficulties.

[selimthegrim]

I believe a recent PBS documentary implicated static electricity.

[dredmorbius]

As an ingnition source for an extremely flammable substance (e.g., hydrogen), possibly. But for the airship skin itself? I ... have grave doubts.

[stan_rogers]

The aluminized dope was an extremely flammable substance.

[dredmorbius]

Sources say otherwise:

A myth has taken hold that the “paint” on the Hindenburg’s skin — rather than its flammable hydrogen lifting gas — was somehow responsible for the Hindenburg disaster at Lakehurst, and this myth somehow persists even though it has been debunked by photographic evidence, scientific analysis, historical research, and even the TV show MythBusters.

https://www.airships.net/hindenburg-paint/

The Mythbusters episode:

https://mythresults.com/episode70

[selimthegrim]

https://www.pbs.org/wgbh/nova/video/hindenburg-the-new-evide... is the one I was recalling