Spider's silk misconceptions

[TithonusSyndrome]

There's something that dosen't feel right about the persistent factoid about how "spider's silk is five times stronger than steel", and I suspect that it has a lot to do with the way it's worded. Perhaps the tensile strength is greater, but is it fair to say that a skyscraper built out of (non-adhesive, for simplicity's sake) spider's silk will collapse onto itself?

[drachefly]

Tensile strength per area density would be the measure they're using, I'd guess. Spider silk is awfully light.

[Darth Yoshi]

IIRC, a strand of spider silk can hold more weight than a strand of steel wool of the same thickness.

[aerius]

It's actually quite simple, they compare it to mild steel which is pitifully weak as far as steels go. On this page the tensile strength of spider silk is listed as around 1150MPa to 1350MPa. For reference, a high strength steel such as Aermet 100 will have a tensile strength of 2000-2100MPa, piano wire is about 3000MPa, and the best small diameter cold-drawn steel wire tops out at 5000MPa or so.

And yes, it's only tensile strength for spider silk, as long as you're only pulling on it it's fine, but you can't push on it any more than you can push on a rope. Meaning you can't build a building with it unless it's woven and bonded with epoxy the way carbon fibre is.

[Winston Blake]

There's something that dosen't feel right about the persistent factoid about how "spider's silk is five times stronger than steel", and I suspect that it has a lot to do with the way it's worded. Perhaps the tensile strength is greater, but is it fair to say that a skyscraper built out of (non-adhesive, for simplicity's sake) spider's silk will collapse onto itself?

IIRC it's not tensile strength, but the tensile strength to weight ratio that is 'five time that of steel'. But that's not really that impressive, since artificial nylon is slightly better. Still, if we could get GM organisms to produce spider's silk, it'd be easy to produce, renewable and environmentally friendly.