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What is b-silkTM protein?

One of Bolt’s subsidiary brands, Eighteen B, recently added a new product, the Defend and Nourish Eye Cream, to the roster of its moisture-delivering, barrier-protecting products. All of Eighteen B’s products use Bolt’s proprietary ingredient, b-silk™ protein. But what exactly is b-silk™, and where does it come from? 

B-silk™ protein was initially developed to be used in one of Bolt’s core innovations, Microsilk™. Microsilk™ is a protein-based fiber inspired by the amazing properties of spider silk. As we studied Microsilk™, we began thinking about the variety of applications for this amazing material.

Knowing the rich history of silk in biomedical engineering and tissue regeneration, we naturally wanted to explore whether our silk proteins might be beneficial in skincare. So, a small group of scientists within Bolt set out to make and test some exploratory formulations. We were happily encouraged by the positive feedback we received from preliminary studies and trials. We knew that we discovered something special and couldn’t wait to share it with the world. We named the pure protein powder b-silk™ protein, and started a skin care company that uses b-silk™ protein as its star ingredient. Inspired by b-silk™ protein’s repeating molecular structure of 18 amino acid segments (or blocks), we named the company Eighteen B.

All of Eighteen B’s products, like the Hydrate + Restore Rich Cream, Revitalizing Hydrogel Moisturizer, Firm + Replenish Serum, and now, the Defend + Nourish Eye Cream, use b-silk™ protein as its core ingredient. 

Just like Microsilk™, b-silk™ protein was inspired by the properties of spider silk. Spider silk has a unique molecular makeup that makes it stronger and stretchier than the commonly used silkworm silk. Like natural silk proteins, b-silk™ protein is a high molecular weight structural protein that complements the vital functions of your skin and reinforces its extracellular matrix (a.k.a. collagen and elastin, the proteins that begin to break down as we age).

Silk proteins are strong, soft, and biocompatible, making them perfectly suited for use in skincare products. When silk proteins are used in other skincare products, they are usually fragmented into smaller pieces using a process called molecular hydrolysis. This process breaks down a bigger molecule (polymer) into many smaller molecules (monomers) by severing the bonds that hold monomers together. Hydrolyzed silk proteins are highly processed and degraded, which can compromise their valuable properties and effects.

B-silk™ protein, on the other hand, is not hydrolyzed. Through rigorous testing, we came up with a formula that keeps the molecular structure intact. B-silk™ protein is engineered in our labs using a simple fermentation process in which the inputs are yeast, water, sugar, and salt. The proteins are left intact – never hydrolyzed. The intact molecular structure delivers more benefits, for better results.

Why? The size of a protein is often measured in Daltons. B-silk™ protein is ~80,000 Daltons, while hydrolyzed silk can be less than 500 Daltons. That is two orders of magnitude (or 100 times) smaller.

The results speak for themselves. Eighteen B’s customers love b-silk™ protein’s lifting, firming, and smoothing properties. In a clinical trial measuring the impact of b-silk™ protein on skin, 71% of women saw an improvement in skin lifting, 91% experienced improved skin texture, and 94% saw firmer skin.

To learn more about Eighteen B and all the ways b-silk™ protein can beneficial in a skincare regimen, visit and Eighteen B’s blog, The Lab.


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Disclaimer: We know learning about the potential of biomaterials can inspire a wealth of ideas and we love your creativity. Before you send us your awesome ideas, please know that we don't want to accidentally come up with an idea similar to yours, so any concept you email us will become the property of Bolt Threads Inc.