In this timeline's equivalent of medieval level development, spider silk is dirt cheap, and cross-laminated sheets of spider silk are quite affordable.

Portia jumping spiders were domesticated hundreds of millennia ago, ballooning their number of neurons to several million. Consequently, they have many new cognitive abilities, such as transmitting and receiving instructions like a bee's waggle dance (but more efficiently using small rapid movements of their iridescent legs), recognizing faces (also like bees), and even limited self-awareness (though since some ants can pass the mirror test, it's clearly much less cognitively demanding than people usually think).

Spider silk has its disadvantages, like its elasticity and flammability in a setting where Greek fire and psychics able to shoot optical lasers are both decently common. But you could also use reflective materials and asbestos in addition.

Notably, many of spider silk's limitations seem like they can be ameliorated by binding cross-laminated layers of spider silk into sheets using resin.

The process of creating cross-laminated sheets of spider silk can be almost entirely done by the spiders, along with trained domesticated dwarf mammoths and crows. For instance, pre-stressing by having the dragline laid out between pegs so the ends can be pulled by birds to keep a layer taut until the resin has poured and dried.

I was imagining this cross-laminated material would likely replace metal and wood in a huge variety of contexts as armor and a structural material. However, I don't know enough about materials like this to predict where people would still want to use metal beyond obvious cases like weaponry (since I wouldn't expect this sort of resin composite to hold an edge) and cooking utensils. In much the same way, I don't know if there's any practical application where this wouldn't beat out wood.

So just how ubiquitous should this stuff be?
Would it be used for nearly everything like plastics are today?(or possibly even more so) Or would the ideal use cases be more limited than I initially thought?

This question considers medieval technology levels, but Earth in this the timeline is vastly more connected than our own. So you needn't be limited to the plants that medieval Europe had access to.

Part of series with:
How much would this alien parasite increase crop yields? What Bronze Age Jobs Couldn't be Replaced by Extremely Well Trained Animals?
How Big Can An Ancient Bird Powered Glider Get?

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    $\begingroup$ +1 nice one to think about.. btw I guess "ubiquitous" is the same as "common" or "omnipresent" ? $\endgroup$
    – Goodies
    Jan 17 at 22:26
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    $\begingroup$ @Goodies Yes, though I'm thinking it might be a good idea to change it it's not as commonly used as I thought. I thought it was around as well known as omnipresent. $\endgroup$ Jan 17 at 22:30
  • $\begingroup$ this timeline's equivalent of medieval level development & in a setting where Greek fire and psychics able to shoot optical lasers are both decently common ??? $\endgroup$
    – L.Dutch
    Jan 18 at 5:25
  • $\begingroup$ @L.Dutch I mean greek fire is bronze age not even medieval. Plus the psychics don't need an understanding of optics to shoot lasers, anymore than traditional fictional psychics need an understanding of Newtonian physics to use telekinesis. $\endgroup$ Jan 18 at 5:28

1 Answer 1


Probably Not as Much As You'd Think

First, I'm skeptical that the stuff could be made "cheap", particularly in the medieval period. Your spider farmer would need to farm millions of spiders, protect the spiders from predation and disease, and train all the associated animals, none of which is light-labour activity, particularly in the medieval period.

Silkworms were domesticated in China, and silk was still (and remains!) an immeasurably precious material. If you made spider silk as cheap as silkworm silk, it would still be more than anyone but royalty could afford.

But assuming that enormous swathes of land were given over to spider farming (shudder), and the feeding and caring of these spiders was inexplicably lower-labour than it should be (worrying), you've got something similar to carbon fibre. That stuff is less expensive these days, but still not used in a lot of applications because its properties don't suit them.

Metal can be readily shaped and reshaped, so armour can be repaired after battle. A resin-matrix spider silk panel would need full-replacement and couldn't be made to measure cheaply. It might be useful for royal armour, but your average soldier or knight would be unable to afford it.

No matter how cheaply it can be made, wood would still be preferable for structural material, because you don't need to spend months fabricating a forty-foot central beam with the aid of billions of spiders, you can just cut a tree down. Trees are available everywhere, not just where the spider farms are.

In a modern era, it would be far more ubiquitous. But in the medieval era, the necessary specialization would be far too much to expect. It would have niche applications, and not much more.

  • $\begingroup$ Made me think, there'd be "faux S-silk", i.e. beams with a thin layer of resin/silk made to look like the real thing, the same with leather armour, a bit like EPNS or gold-plating. $\endgroup$ Jan 17 at 22:40
  • $\begingroup$ The spiders are cheap in large part because of the massive role of domesticated crows: Their is already major infrastructure for farming insects as feed, and those birds can protect them and deliver them food regularly. People also typically have multiple of these spiders with them at any time, in analog spider based computers and on their shoulders with their iridescence serving a similar role to jewelry. $\endgroup$ Jan 17 at 23:06
  • $\begingroup$ @VakusDrake - "Multiple" is insufficient, unfortunately. A single outfit of spider silk would take the output of millions of spiders. Silkworms produce more than a thousand times the silk/day that spiders do, and the average silk shirt requires a thousand silkworms' output. And that the infrastructure exists doesn't make it any easier. Infrastructure existed for farming grain, and it was still back-breaking labour for hundreds of thousands of peasants. $\endgroup$
    – jdunlop
    Jan 18 at 3:20
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    $\begingroup$ @VakusDrake Mostly extrapolation. Silkworm silk strands are ten times thicker than spider silk strands. It takes about a thousand silkworm cocoons (created over about 4-6 days) to create a silk shirt; making a vest of spider silk took a million spiders and six months. Recent advances in spider silk body armour involved splicing spider silk proteins into silkworms for radically increased output or it would be untenable. $\endgroup$
    – jdunlop
    Jan 18 at 21:53
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    $\begingroup$ @VarkusDrake the Golden Silk Orb-Weaver, one of the most-silk-producing spiders, can produce about 1.2 mg of silk per day, and it needs to use some of that silk to wrap its prey for feeding. The average silkworm cocoon (again, spun over 4-6 days) weighs 1.4g. So in Fermi numbers, that's a thousand. In practical numbers, maybe just a few hundred times as many spiders as silkworms. $\endgroup$
    – jdunlop
    Jan 18 at 21:57

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