The 500 Dalton Rule: Why Effective Skincare Should Protect and Nourish Your Skin

If you’ve spent any time researching skincare, you’ve probably come across something called the 500 Dalton Rule. It’s often mentioned as a way to explain why some ingredients can penetrate the skin while others primarily remain on the surface.

At Naturally Lathered Tallow Co., we don’t see skincare as an either-or proposition.

We believe healthy skin is best supported by products that both help protect the skin’s natural barrier and provide ingredients that help keep it moisturized and conditioned. That’s the philosophy behind every formula we create.

What Is the 500 Dalton Rule?

Your skin’s outermost layer, known as the stratum corneum, serves as an incredibly effective protective barrier. One widely accepted concept in dermatology suggests that molecules larger than approximately 500 daltons generally have difficulty passing through this outer layer, while many smaller molecules are more likely to penetrate it.

It’s important to understand that this is a guideline—not an absolute law.

Whether an ingredient penetrates the skin depends on several factors, including its molecular size, chemical structure, solubility, concentration, the formulation it’s part of, the condition of the skin, and how the product is applied.

Rather than viewing skincare through a simple “penetrates or doesn’t” lens, modern formulation recognizes that different ingredients perform different jobs—and many of those jobs happen right where they’re needed.

Why This Matters

Many skincare products focus primarily on one objective.

Some are designed to create a protective barrier that helps reduce moisture loss from the skin’s surface.

Others are formulated to deliver ingredients that help moisturize and condition the upper layers of the skin.

At Naturally Lathered Tallow Co., we believe the best skincare combines both approaches.

Our Philosophy

Every product we formulate is carefully designed with two purposes in mind.

First, to Protect

Our locally sourced, grass-fed, grain-finished beef tallow helps form a breathable protective layer that reduces transepidermal water loss (TEWL)—the natural process through which water evaporates from the skin.

Rather than creating a heavy synthetic coating, tallow helps lock in your skin’s own moisture while allowing the skin’s natural barrier to function as intended.

This protective layer helps skin stay soft, comfortable, and better able to retain hydration throughout the day.

Second, to Nourish

Protection alone isn’t enough.

Tallow contains a unique profile of fatty acids—including oleic, palmitic, stearic, and palmitoleic acids—that are also naturally present in human skin. Along with naturally occurring fat-soluble vitamins, these lipids help condition the skin and support a healthy moisture barrier.

Many of our formulations also include thoughtfully selected botanical oils, plant extracts, and other skin-compatible ingredients chosen for their moisturizing and conditioning properties.

Rather than relying on a single ingredient to do everything, we formulate products that work together to support healthy, hydrated skin.

Why Tallow Makes Sense

Long before modern skincare existed, people relied on tallow as a trusted moisturizer.

Today, modern skin science helps explain why it has remained a valued skincare ingredient for generations.

Because its lipid profile shares similarities with the skin’s own protective barrier, many people find that tallow spreads easily, absorbs comfortably, and leaves skin feeling soft and conditioned without relying solely on synthetic ingredients.

Our goal isn’t simply to coat the skin.

Our goal is to help support the skin’s natural barrier while providing lasting hydration and everyday comfort.

Why Formulation Matters

No single ingredient determines how a skincare product performs.

The balance of oils, butters, waxes, botanical extracts, emulsifiers, and other supporting ingredients all influence how a product feels, spreads, absorbs, and helps maintain skin hydration.

That’s why we spend so much time refining every formula.

Thoughtful formulation matters just as much as choosing high-quality ingredients.

Every ingredient has a purpose, and every product is carefully balanced to work as a complete system rather than relying on a single “hero ingredient.”

More Than Just Moisture

Healthy skin depends on a strong, well-functioning skin barrier.

When that barrier becomes compromised, moisture escapes more quickly, leaving skin feeling dry, rough, or uncomfortable.

That’s why our products are designed with two primary objectives:

• Help reduce moisture loss by forming a breathable protective layer.
• Help moisturize and support the skin’s natural barrier with skin-compatible ingredients.

We believe healthy skin doesn’t come from driving ingredients unnecessarily deep into the skin.

It comes from respecting your skin’s natural biology and giving it the support it needs to function at its best.

Our Commitment

At Naturally Lathered Tallow Co., every formula is created with intention.

We don’t chase trends.

We don’t overload our products with unnecessary ingredients.

Instead, we focus on carefully crafted formulations that combine time-honored ingredients with today’s understanding of skin science.

The result is skincare designed to help protect the skin’s natural barrier, maintain healthy moisture levels, and leave skin feeling soft, comfortable, and well cared for.

We believe nature and science don’t have to compete—they work best together.

By respecting both traditional ingredients and modern research, we’re proud to create products designed to help your skin look and feel its very best.

References

Bos JD, Meinardi MMHM. The 500 Dalton Rule for the Skin Penetration of Chemical Compounds and Drugs. Experimental Dermatology. 2000.

Elias PM. Skin Barrier Function. Journal of Investigative Dermatology.

Proksch E, Brandner JM, Jensen JM. The Skin: An Indispensable Barrier. Experimental Dermatology.

Lodén M. Role of Topical Emollients and Moisturizers in the Treatment of Dry Skin Barrier Disorders. American Journal of Clinical Dermatology.