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Our most potent formula yet, Serum is packed with a double dose b-silk™ protein, our proprietary key ingredient.
Firm + Replenish Serum is our third product made with b-silk™ protein, our proprietary ingredient. Designed to replenish your skin barrier before moisturizing, Serum is an essential step in your skincare regimen. Here’s why.
Our most concentrated formula yet, Firm + Replenish Serum is packed with a double dose of b-silk™ protein, our proprietary key ingredient.
Our multi-tasking Serum has two main functions. First, Serum works to replenish skin’s barrier after cleansing and exfoliating and prime skin for moisturizer (more on this below).
Then, b-silk™ protein forms a lightweight, breathable barrier that protects skin from environmental stressors. Over time, b-silk™ protein works to deliver long-term firming, visible lifting, and increased elasticity.
What is the skin barrier?
If you’ve read our Deep Dives on Hydrate + Restore Rich Cream and Revitalizing Hydrogel Moisturizer, you know that b-silk™ protein works to reinforce the skin barrier, leading to healthy, radiant skin. Here’s a refresher course on the skin barrier. But what exactly is the skin barrier?
Also known as the stratum corneum, the skin barrier is the skin’s outermost layer. Its structure is similar to a brick wall, with old skin cells (a.k.a. corneocytes) stacked and held together by lipids and fats.
A healthy skin barrier performs two functions. First, it helps your skin retain moisture by preventing water loss from deeper skin layers. Second, it helps protect your skin from harsh elements like UV rays, pollutants, microbes, and chemicals.
Your skin barrier’s function is a direct result of many factors, including nutrition, age, your daily skincare routine, and your surrounding environment. Over time, the barrier starts degrading and gets weaker and a little worse at performing its function. To further complicate matters, every time you cleanse, fats and lipids are stripped from the skin, weakening the skin’s barrier function. This brings on moisture loss, and lets in external aggravators, which further damage the deeper layers of skin by breaking down structural proteins like collagen and elastin.

Where does Serum come in?
The first job of Firm + Replenish Serum is to replenish the skin’s barrier after cleansing and exfoliating. Our Serum is packed with Natural Moisturizing Factor (NMF), a cocktail of Amino Acids, PCA, Hyaluronic Acid, and more that the skin naturally creates to keep the stratum corneum and epidermis hydrated. Our Serum delivers a potent dose of NMF so your skin doesn’t need to work so hard to replenish these ingredients on its own.
Next up: b-silk™ protein. Our innovative key ingredient mimics your natural barrier function and provides a breathable layer of reinforcement against the elements. B-silk™ protein works to lock in the NMF ingredients so they can do their work on the skin.
After applying Serum, you moisturize. Serum is packed with hydrating ingredients, but it feels clean and smooth rather than deeply hydrating. Once skin is primed, apply our lightweight Revitalizing Hydrogel Moisturizer or our decadent Hydrate + Restore Rich Cream to hydrate the skin. By day, top it off with an SPF. By night, you’re good to go.

What’s Inside?
B-silk™ protein
Our proprietary ingredient forms a lightweight, breathable barrier that locks moisture in and keeps environmental factors at bay. When b-silk™ protein is applied, tiny silk molecules lock together to form an invisible film on the surface of your skin. Unlike many other barrier-forming ingredients, the b-silk™ protein barrier is not greasy and allows your skin to perform its function while providing vital reinforcement. Read more about b-silk™ protein here.
Natural Moisturizing Factor (NMF)
The Natural Moisturizing Factor (NMF) is a cocktail of Amino Acids, PCA, Hyaluronic Acid, and more that the skin naturally creates to keep the stratum corneum and epidermis hydrated. Here’s what each of those ingredients does.
Amino Acids
There are two types of Amino Acids: non-essential and essential. Non-essential Amino Acids are produced by the body (such as in NMF). Essential Amino Acids not produced by the body and must be taken in by foods and supplements. Our Serum is made with both types of Amino Acids, including Alanine, Arginine, Aspartic Acid, Glycine, Histidine, Isoleucine, Phenylalanine, Proline, Serine, Threonine, and Valine. Amino Acids work to keep the skin hydrated, strengthen the immune system, and protect skin from free radicals.
Pyrrolidone Carboxylic Acid (PCA)
Pyrrolidone Carboxylic Acid (PCA) is a humectant (a substance used to reduce moisture loss) that is part of the skin’s NMF. When applied topically, PCA helps replenish the NMF for skin that appears hydrated, smooth, and firm.
Hyaluronic Acid (HA)
Hyaluronic Acid (HA) is another powerful humectant found in the skin’s Natural Moisturizing Factor. And we mean powerful – HA can hold approximately 1,000 times its weight in water. HA works like a magnet to hold moisture, helping your skin look hydrated and healthy. When our skin is more hydrated, it appears plumper and fine lines are less visible.
Ceramides
Ceramides are essential lipids that help restore skin integrity and elasticity, fortify the skin barrier, and make the skin look plump and firm. They are naturally produced by the skin, but can be depleted by cleansing, chemicals, and environmental factors. Firm + Replenish Serum contains three types of naturally-occurring ceramides: Ceramide AP, EOP, and NP. All of these have a slightly different molecular structure and work in concert to support barrier function.
Let’s See the Results.
In a consumer trial, users reported results in as little as seven days. With continued use, skin keeps getting better.
Want to see for yourself? Shop Firm + Replenish Serum today to get started.

Do you have questions? Comments? Topics you want us to cover? We’d love to hear from you. Email us at thelab@eighteenb.com.