The Spool

How Much Does It Cost to Make Spider Silk Without Spiders?

If you’re a regular reader of The Spool you already know that we’re not the first group to harness the power of spider silk, either from spiders themselves or by developing technology.

The many approaches used over time have various advantages and disadvantages, including cost of manufacture. In fact, one of the questions we get asked most often is: How much will your silk sell for?

To get a sense of what previous textiles based on spider silk cost, consider the tapestry commissioned by Nicholas Godley and Simon Peers, which was made from silk reeled from golden orb spiders.

The 11×4 foot tapestry required 80 people, more than one million golden orb spiders, and $500,000. That’s just under $20,000 per square foot!

However, we’re using a much more scalable technology: large scale yeast fermentation, which is a well-known process with established costs. In this model, some costs are given:  the price of nutrients for the yeast, capital equipment, and operating expenses to run facilities and employ our talented staff. Other costs are determined by our scientific process, including the amount of silk protein the yeast can make, how much time they ferment, and the cost of purifying the silk protein to be spun into fibers.

Another company working on producing spider-silk polymers attempted an estimate of our costs that demonstrated a considerable lack of understanding of our process, leading to a cost estimate for Bolt Threads that is orders of magnitude higher than reality.

Aside from the fact that one should take an estimate by a direct competitor with a grain of salt, their calculations contained a significant error, which stems from their lack of understanding of the scale at which we operate. Operating at industrial scale, we significantly lower the cost per unit of yeast we ferment.

Process optimization is also on our side. As we repeatedly run our process and optimize the productivity and robustness of each step, we are able to produce increasing levels of silk protein. Over time efficiency of the process goes up and costs continue to come down.

By using large scale industrial yeast fermentation, we can produce fibers at a cost on par with other sources of fine fiber like silkworm silk and fine wools – a far lower price than some previous estimates.




Bolt Threads
5858 Horton St, Suite 400
Emeryville, CA 94608

(415) 325-5912
For press inquiries:
For career inquiries: