Plant oils and butters in vegan bar soap: what each one contributes (and how to pick the right blend)

The secret behind every great bar is the oil blend

When someone says, “I love this bar,” they’re usually reacting to a few specific things:

• how quickly it lathers

• whether the bubbles feel creamy or airy

• how the rinse feels (clean, comfortable, tight, silky)

• whether the bar lasts or melts away

• whether skin feels calm afterward

All of that comes back to one core design choice: the blend of plant oils and butters.

In vegan bar soap, oils and butters are doing double duty. They create the soap itself (through saponification), and they determine the sensory experience of cleansing. That’s why two vegan bars can both be “natural,” both be “handcrafted,” and still feel completely different.

This post breaks down what common plant oils and butters contribute, why fatty acids matter, and how to choose a blend that matches your skin and lifestyle.

A quick primer: fatty acids are the “building blocks” of soap

Plant oils are made of different fatty acids in different ratios. In soapmaking, those fatty acids are associated with different performance traits. You don’t need to memorize them, but a basic understanding helps.

Common fatty acids you’ll hear about:

• Lauric and myristic acids: strong cleansing and big bubbles

• Palmitic and stearic acids: hardness, longevity, creamy lather

• Oleic acid: conditioning feel, gentleness, softer lather

• Linoleic and linolenic acids: lightweight feel, can support a softer conditioning profile

• Ricinoleic acid (from castor oil): lather stability and creaminess

A good bar balances these traits. Too much cleansing can feel drying; too much conditioning can feel soft, slimy, or low-lather in certain water.

Coconut oil: bubbles and cleansing power (when balanced)

Coconut oil is famous in soapmaking because it produces abundant lather and a very “clean” rinse. That’s why it’s common in bars designed for:

• sweaty days

• post-workout showers

• body cleansing that feels crisp and fresh

But coconut oil can be too cleansing at high percentages for some skin types—especially in winter, for people who run dry, or for those with a sensitive barrier. The best formulas treat coconut oil as a tool, not the whole plan: it’s paired with more conditioning oils and butters so the bar stays effective without feeling harsh.

If you love big bubbles and a clean rinse, coconut oil is often part of the reason.

Olive oil: gentle conditioning and a comfortable rinse

Olive oil is associated with a milder, more conditioning feel. Bars with a higher olive oil presence often feel:

• less stripping

• more comfortable for frequent cleansing

• creamier and calmer on the skin

Some people describe olive-forward bars as “silky” or “lotion-like” in lather. In hard water, though, olive-heavy bars can sometimes feel lower-lather compared with more bubbly blends. If you live in hard water and love olive oil bars, pairing them with a cloth lather routine can make the experience more consistent.

Olive oil is a great example of how a bar can feel gentle without needing a ton of extras.

Castor oil: the lather stabilizer that improves texture

Castor oil is often used in smaller percentages because it’s powerful in a specific way: it helps stabilize bubbles and improve the density of lather. It can make foam feel:

• thicker

• creamier

• more “cushioned”

If you’ve ever used a bar that lathers quickly but the bubbles disappear fast, castor oil is one ingredient that can help prevent that “flash foam” effect.

Castor oil is rarely the star, but it often makes the bar feel more polished.

Sunflower, safflower, and other lightweight oils: softness and skin feel

Oils like sunflower and safflower are often included for a lighter conditioning profile. They can contribute to a bar that feels:

• smoother

• less heavy

• comfortable for people who dislike a waxy rinse

These oils tend to be higher in linoleic acid, which is why they’re often associated with a lighter feel. In soap, they’re usually balanced with harder oils and butters to ensure the bar still feels solid and long lasting after curing.

Shea butter: creaminess, structure, and a luxurious feel

Shea butter is a favorite in vegan skincare for a reason: it brings richness. In bar soap, shea butter is often used to add:

• creamier lather

• more structure and hardness

• a more “comforting” rinse feel

If you prefer bars that feel nourishing rather than crisp, shea butter is often a key part of that sensation.

For dry or winter-prone skin types, bars with butters can feel more comfortable as part of a barrier-friendly routine.

Cocoa butter: firmness and longevity (with a smooth finish)

Cocoa butter helps create a firmer, longer-lasting bar with a refined feel. In soap, it can contribute to:

• hardness and durability

• a smoother finish

• a stable lather profile

Cocoa butter is also one of the reasons some bars feel like they “hold up” better in the shower and don’t go mushy as quickly (especially when paired with good storage habits).

Mango butter: silky conditioning without feeling too heavy

Mango butter is often used for a silky, balanced feel—conditioning without being overly greasy. In a vegan bar, it can support:

• creamier lather

• a smooth glide

• a pleasant after-feel that many people like year-round

It’s especially popular for shoppers who want something moisturizing-feeling but still light enough for daily use.

Clays and botanicals: performance add-ons, not the foundation

While oils and butters build the core bar, add-ons can fine-tune the experience.

• Kaolin clay can add slip and a softer glide

• Bentonite clay is often chosen for a deep-clean vibe

• Botanical infusions can add character and story to the bar, and sometimes a subtle skin feel difference depending on the ingredient

The key is moderation. The bar should still feel good on day 30, not just on day 1.

How cure time interacts with oils and butters

People sometimes judge a bar too quickly. Cure time changes how the oil blend expresses itself in real use.

With proper curing:

• bars get harder

• lather becomes more stable

• rinse feel becomes more consistent

• the bar lasts longer

This matters especially for softer oils. A bar with more conditioning oils can still be long lasting when it’s formulated well and cured properly, but it benefits from that time.

How to choose a blend based on your skin and routine

Instead of choosing a bar by trend, choose it by goal.

If you want a crisp, fresh cleanse

Look for blends with:

• coconut oil for bubbles and cleansing

• supportive butters or olive oil for balance

Best for:

• post-workout showers

• humid summers

• people who love a very clean rinse feel

If you want an everyday comfortable bar

Look for blends with:

• olive oil and conditioning oils

• a butter (shea, mango, cocoa) for structure

• castor oil for lather stability

Best for:

• daily showers

• normal to slightly dry skin

• people who dislike the “tight” feeling after washing

If your skin runs dry or reactive

Consider:

• fragrance-free or lightly scented options

• butter-forward blends (shea/mango/cocoa)

• targeted cleansing (underarms, feet, etc.) instead of over-washing everything

Best for:

• winter routines

• sensitive skin patterns

• anyone trying to support their skin barrier

Face vs body: why one bar doesn’t always do both

Some people love using one bar for everything. Others find their face prefers a different approach.

Facial skin can be more reactive and often needs:

• gentler cleansing

• less fragrance

• less exfoliation

• consistent moisturizing afterward

If you try a bar on your face:

• start a few times a week

• avoid very hot water

• patch test if you’re sensitive

• pay attention to tightness or redness

There’s no shame in using one bar for body and a gentler routine for face if that’s what your skin wants.

Water hardness changes how oils and butters feel

Even the best oil blend can feel different depending on water.

• In hard water, bubbly/cleansing blends can feel more satisfying because they lather more easily under mineral interference.

• In soft water, butter-rich bars can feel extra creamy, and lather can build quickly.

If you want consistent results across water types, a washcloth lather routine helps almost every formula perform better.

A practical “ingredient label” example you can interpret

Let’s say a label starts with:

• olive oil

• coconut oil

• shea butter

• castor oil

• essential oils

That typically suggests:

• balanced cleansing (coconut oil)

• conditioning comfort (olive oil)

• creamy structure (shea butter)

• lather stability (castor oil)

• a naturally scented profile (essential oils)

You don’t need to obsess over every ingredient. Learn the roles, then choose the feel you want.

FAQs

Does more lather mean better cleansing?
Not always. Lather is partly performance and preference. A gentle bar can cleanse well with creamy lather rather than huge bubbles.

Why do some bars feel drying?
Often it’s a combination of strong cleansing oils, hot water, long showers, and skipping moisturizer afterward.

Do butters clog pores?
In rinse-off products like soap, the risk is usually lower than leave-on products, but skin is individual. If you’re acne-prone, patch test and adjust frequency.

What’s the best oil for sensitive skin?
There isn’t one universal best. Many people do well with conditioning blends and minimal fragrance, but you’ll get the best answer by testing gently and watching how your skin responds.

Closing thought

Plant oils and butters are the real “design language” of vegan bar soap. Once you understand their roles, you can stop guessing and start choosing bars that match your routine—whether you want a fresh post-gym cleanse, a calm winter bar, or an everyday option that feels comfortable and consistent. Waterfall Glen Soap Company builds its bars around that ingredient-first mindset, using plant oils, butters, and botanical infusions to create a cleansing experience that supports both skin comfort and planet-minded values.

NIH PubChem: lauric acid

NIH PubChem: oleic acid