Beginner's Guide to Soap & Bath Product Additives: What They Do & How to Use Them
When you're first learning how to make handmade soap and bath products, the ingredient list can seem overwhelming. Oils, butters, lye, fragrance, colorants—and then you start seeing ingredients like sodium lactate, Polysorbate 80, Tussah silk, sodium citrate, and colloidal oatmeal.
What do all of these ingredients actually do?
The good news is that you don't need to use dozens of additives to make beautiful handmade soap. Additives are simply ingredients added to a basic soap or bath formulation to give the finished product a particular texture, appearance, performance, hardness, lather, skin feel, or other characteristic.
Some are incredibly useful for beginners, while others are more specialized.
In this guide, we'll look at some of the most popular additives used in handmade soap and bath products, including what they do, when to use them, and beginner-friendly tips for working with them.
This page contains Amazon affiliate links. I may earn a small commission if you purchase through these links, at no extra cost to you. I only recommend products I personally use or trust.
Related Posts:
Cold Process Soap for Beginners: Everything You Need to Start
Top 6 Highest Rated Books to Learn Soapmaking
Top 6 Most Affordable Oils for Soap Making & Skincare (Beginner-Friendly)
Melt and Pour Soap vs Cold Process: The Easiest Way to Start Soap Making
My Favorite Soap & Bath Making Supplies – Blue Dragonfly Handmade
1. Sodium Lactate
If you're making cold process soap, sodium lactate is one additive I would recommend beginners learn about early.
Sodium lactate is the sodium salt of lactic acid and is commonly used in soapmaking as a hardening and processing aid. It can help freshly unmolded cold process soap feel firmer and can make the finished bar easier to remove from the mold.
One of its most useful properties is that it can also make soap batter feel smoother and easier to work with. This can be particularly helpful when you're using molds where unmolding can otherwise be difficult.
Sodium lactate is especially popular in recipes containing softer oils or when you're using silicone molds.
Benefits
- Helps harden freshly made soap
- Makes bars easier to unmold
- Can improve the feel of finished soap
- Helps make soap batter easier to handle
- Useful with silicone molds
Perfect For
- Cold process soap
- Melt-and-pour formulations
- Recipes with softer oils
- Detailed silicone molds
- Beginner soapmaking
Beginner tip: Sodium lactate is usually added to the cooled lye water rather than directly to the oils. Follow your supplier's recommended usage rate—commonly around 1 teaspoon per pound of oils.
Recommended: Sodium Lactate
2. Polysorbate 80
Polysorbate 80 is a solubilizer and emulsifying surfactant that is especially useful in bath products. It helps water and oil-based ingredients disperse more evenly instead of separating or leaving a large layer of oil floating on the bath water.
This makes it particularly useful in bath bombs, bath salts, bath oils, and other products containing fragrance or essential oils.
For example, when you add fragrance oil or colorant to a bath bomb without a suitable dispersing ingredient, that oil and color can remain concentrated on the surface of the bath water as well as the tub after draining. Polysorbate 80 helps disperse the oil more evenly throughout the water.
It can also help reduce the amount of oily residue left behind on your bathtub.
Polysorbate 80 is not used in soap.
Benefits
- Helps disperse oils in water
- Reduces floating oil
- Helps minimize bathtub residue
- Improves bath bomb performance
- Helps fragrance oils disperse more evenly
Perfect For
- Bath bombs
- Bath salts
- Bath oils
- Bubble baths
- Shower steamers
Beginner tip: Polysorbate 80 is not an essential ingredient for cold process soap. It's much more useful when you're making products where oil and water need help dispersing.
Recommended: Polysorbate 80
3. Tussah Silk
Tussah silk is a favorite among soapmakers who want to give their cold process soap a luxurious, silky skin feel. Tussah silk comes from the fibers produced by wild or semi-domesticated silkworms, rather than the cultivated silkworms traditionally associated with conventional silk production.
In soapmaking, very small amounts of silk fiber are added to the lye solution, where the strong alkaline solution breaks down the fibers and allows the silk proteins to become incorporated into the soap.
The result isn't a bar of soap containing visible pieces of silk. Instead, the silk is used to give the finished soap a smooth, silky feel and potentially improve the perceived creaminess of the lather.
Benefits
- Creates a silky skin feel
- Can give lather a luxurious quality
- Adds a premium touch to soap
- Works particularly well in creamy soap recipes
- Requires only a very small amount
Perfect For
- Cold process soap
- Luxury soap
- Facial soap
- Creamy soap recipes
- High-end gift soaps
Important: Tussah silk is an animal-derived ingredient, so it isn't appropriate for vegan soap. If you're marketing your soap as vegan, choose a plant-based alternative.
Beginner tip: Use only a very small amount. Cut or pull the silk into tiny pieces and add it to your lye water according to your supplier's instructions. Add while solution is hot to allow ample time for the silk to be broken down and disolved.
Recommended: Tussah silk
4. Sugar
Sugar is one of the simplest and most affordable soap additives, and it's especially useful when your goal is more bubbles.
Sugar is added to the soapmaking process because dissolved sugar can help encourage a more abundant, bubbly lather. This can be particularly helpful in recipes that contain less coconut oil or other naturally bubbly oils.
You don't need much sugar to see an effect, and too much can create problems such as overheating. A 900 gram total oil batch would need just 1 tsp of sugar, max.
Benefits
- Boosts bubbly lather
- Can make bubbles feel more abundant
- Inexpensive
- Easy to find
- Useful for low-coconut recipes
Perfect For
- Cold process soap
- Bubble bars
- Bath products
- High-lather recipes
- Beginner soapmaking
Beginner tip: Dissolve your sugar completely in your water before adding the lye, or use another method recommended for your particular recipe. Too much sugar can cause soap to heat up considerably.
5. Sodium Citrate
Sodium citrate is a useful but sometimes overlooked soapmaking additive. It is the sodium salt of citric acid and acts as a chelating agent.
Why does that matter?
Hard water contains minerals such as calcium and magnesium. These minerals can react with soap and contribute to soap scum. A chelating agent can bind some of these metal ions and help reduce their interaction with the soap.
Sodium citrate can therefore be especially useful for soapmakers dealing with hard water.
Benefits
- Helps bind hard-water minerals
- Can reduce soap scum
- May improve soap performance in hard water
- Helps support a cleaner-feeling rinse
- Useful alternative to some commercial chelators
Perfect For
- Cold process soap
- Hard-water areas
- Shampoo bars
- High-quality cleansing bars
- Soap designed for frequent use
Beginner tip: Sodium citrate can be made from citric acid and sodium hydroxide, but for beginners, purchasing ready-made sodium citrate can simplify formulation.
Recommended: Sodium citrate
6. Kaolin Clay
Kaolin clay is technically a natural mineral ingredient rather than a traditional "additive," but it's such a useful soapmaking ingredient that it deserves a place on this list.
This fine white clay is especially popular because it can provide slip, a silky skin feel, gentle oil absorption, and natural color. It's one of the easiest clays for beginners to experiment with.
Kaolin is particularly popular in shaving soap because of the slip it can provide, but it also works beautifully in facial soaps and everyday body bars.
Benefits
- Adds slip
- Creates a silky skin feel
- Provides gentle oil absorption
- Adds natural color
- Can improve the feel of lather
Perfect For
- Shaving soap
- Facial soap
- Cold process soap
- Clay masks
- Gentle cleansing bars
Beginner tip: Disperse kaolin in a small amount of the recipes oil before adding it to the rest of your soap batter to help prevent clumps.
Recommended: Kaolin clay
7. Colloidal Oatmeal
Colloidal oatmeal is finely milled whole oat material designed to disperse evenly in water. Unlike coarse oatmeal, which can feel scratchy, colloidal oatmeal creates a smooth addition to skincare products.
It contains naturally occurring starches, beta-glucans, proteins, lipids, and other oat compounds that can help give products a soothing, conditioning skin feel.
It's especially popular in products intended for dry or easily irritated-feeling skin.
Benefits
- Provides a soothing skin feel
- Helps condition the skin
- Adds softness
- Can improve the feel of soap
- Provides a gentle, creamy texture
Perfect For
- Cold process soap
- Bath soaks
- Oatmeal bath products
- Body washes
- Gentle facial products
Beginner tip: Use finely milled colloidal oatmeal, not large pieces of rolled oats, when you want a smooth skincare product. You can add the oats into the melted oils before adding your lye solution.
Recommended: Colloidal oats
8. Honey
Honey is a popular natural additive because it can contribute to the lather, color, and overall character of handmade soap.
It contains sugars, which can help encourage lather, but that same sugar content means honey can make soap heat up quickly. In cold process soap, too much honey—or adding it without taking precautions—can cause the batter to become excessively hot or even overheat.
Honey can also darken soap, producing beautiful cream, tan, golden, or brown shades depending on the amount used and the rest of the recipe.
Honey is not something I would recommend for a beginner. Honey soaps are typically more advanced.
Benefits
- Can boost lather
- Adds a luxurious ingredient
- Provides natural sugars
- Creates warm golden tones
- Gives soap a beautiful marketing story
Perfect For
- Honey soap
- Milk and honey soap
- Facial bars
- Luxury soap
- Gift soaps
Beginner tip: Start with a small amount and be prepared for extra heat. Honey soap may need to be refrigerated or otherwise managed carefully depending on the recipe.
Related Posts:
Cold Process Soap for Beginners: Everything You Need to Start
Top 6 Highest Rated Books to Learn Soapmaking
Top 6 Most Affordable Oils for Soap Making & Skincare (Beginner-Friendly)
Melt and Pour Soap vs Cold Process: The Easiest Way to Start Soap Making
9. Milk Powder
Milk powders such as goat milk powder, coconut milk powder, or buttermilk powder are popular soap additives because they can contribute to a creamy, luxurious lather and give soap a beautiful marketing appeal.
Milk contains proteins, sugars, fats, and minerals, although what remains functional in finished soap depends on the specific milk product and the soapmaking process.
Powdered milk can be particularly convenient for beginners because you don't have to deal with the challenges of using fresh liquid milk in a lye solution.
Benefits
- Creates a creamy-feeling bar
- Can contribute to rich lather
- Adds a luxurious ingredient
- Provides beautiful marketing appeal
- Convenient compared with fresh milk
Perfect For
- Goat milk soap
- Coconut milk soap
- Luxury bars
- Facial soap
- Creamy body soap
Beginner tip: Milk products contain sugars, so they can contribute to overheating. Keep temperatures under control and avoid excessive insulation.
Recommended:
Micro Ingredients coconut milk powder
Related Posts:
MY Coconut Milk Soap Recipe (Creamy, Moisturizing + Beginner-Friendly)
Bubble Boosters in Soap Making: What Actually Creates Lather?
10. Salt
Salt is another simple additive that can dramatically change the character of a soap.
In small amounts, salt can help make a bar feel harder and can contribute to a firmer finished product. However, too much salt can significantly reduce lather, which is why the amount you use matters.
Salt bars are a completely different style of soap, often formulated with very high amounts of salt and a high percentage of bubbly oils such as coconut oil.
Benefits
- Can increase bar hardness
- Creates a distinctive skin feel
- Useful in salt bars
- Adds an inexpensive natural ingredient
- Can produce a spa-like experience
Perfect For
- Salt bars
- Spa soaps
- Foot soaps
- Harder cleansing bars
- Specialty soap
Beginner tip: Don't simply add a large amount of salt to your normal soap recipe. Salt bars require a recipe designed specifically around the salt because excessive salt can drastically reduce lather.
Article Coming Soon: How to make salt soap and my sea salt soap recipe!
11. Ground Botanicals
Botanical ingredients are some of the most tempting additives for beginning soapmakers. Who doesn't love the idea of adding dried lavender, rose petals, calendula, coffee, or herbs to handmade soap?
But botanicals need a little caution.
Some dried plant materials can turn brown, bleed color, feel scratchy, or become visually unattractive over time. Others can be perfectly wonderful additions when used appropriately.
Honestly, I would not use flowery or herbal botanicals inside soap, I would use as a decorative topping.
Popular Options
- Calendula petals
- Lavender buds
- Ground coffee
- Finely ground herbs
- Oatmeal
- Rose petals
Benefits
- Adds visual interest
- Provides natural texture
- Creates unique soap designs
- Can reinforce a botanical theme
- Great for specialty and gift soaps
Perfect For
- Artisan soap
- Exfoliating bars
- Garden-inspired soaps
- Specialty gift soaps
- Botanical bath products
Beginner tip: Avoid adding large, sharp pieces of botanicals to soap intended for everyday use. Finely ground or very soft botanicals are generally more comfortable on the skin.
Recommended:
12. Activated Charcoal
Activated charcoal is a finely processed form of carbon with a highly porous structure. It's commonly used in soap because it produces a dramatic gray-to-black color and is associated with cleansing and oil-absorbing formulations.
One important distinction for beginners: charcoal is primarily a colorant and functional cosmetic ingredient, rather than something that makes soap inherently "detoxifying." Marketing claims about charcoal pulling toxins from the body are much stronger than the evidence supports.
Benefits
- Creates dramatic black color
- Can absorb oils
- Adds visual interest
- Useful in cleansing formulations
- Creates a sophisticated appearance
Perfect For
- Facial soap
- Cleansing bars
- Men's grooming products
- Specialty soap
- Dramatic soap designs
Beginner tip: Charcoal can be extremely messy. Start with a small amount and be careful when measuring and dispersing it.
Recommended: Activated Charcoal
Sodium Lactate vs. Polysorbate 80 vs. Tussah Silk
These three additives are sometimes mentioned together in soapmaking groups, but they perform completely different jobs.
| Additive | Main Purpose | Best Used In |
|---|---|---|
| Sodium Lactate | Hardness & easier unmolding | Cold process soap |
| Polysorbate 80 | Helps oils disperse in water | Bath bombs & bath products |
| Tussah Silk | Silky skin feel | Cold process soap |
| Sugar | More bubbly lather | Cold process soap |
| Sodium Citrate | Binds hard-water minerals | Cold process soap |
| Kaolin Clay | Slip & silky feel | Soap & masks |
| Colloidal Oatmeal | Conditioning & soothing feel | Soap & bath products |
| Honey | Lather & luxury ingredient | Cold process soap |
| Milk Powder | Creamy feel & lather | Soap |
| Salt | Hardness & specialty bars | Salt soap |
| Charcoal | Color & oil absorption | Soap & masks |
How Do You Know Which Additive to Use?
The easiest way to choose an additive is to ask yourself:
What do I want my finished product to do?
Want harder soap?
Try sodium lactate or salt.
Want more bubbles?
Try sugar or honey.
Want a silkier bar?
Try Tussah silk or kaolin clay.
Want more slip?
Try kaolin clay or bentonite clay.
Want to work with hard water?
Consider sodium citrate.
Want to make a bath bomb?
Polysorbate 80 is one of the most useful additives to learn.
Want a soothing-feeling bath product?
Try colloidal oatmeal.
Want a creamy-feeling bar?
Try milk powder or colloidal oatmeal.
Want natural color?
Try clays, charcoal, botanicals, or other appropriate cosmetic colorants.
Related: Clays for Soap & Skincare Making Part 1
Beginner Soapmaking Additive Tips
Before you start adding everything in your ingredient cabinet to one batch of soap, remember that more additives don't necessarily mean better soap.
In fact, one of the best things a beginner can do is start simple.
1. Change One Thing at a Time
If you add sodium lactate, honey, milk powder, sugar, clay, and silk to the same batch and something goes wrong, you'll have no idea which ingredient caused the problem.
Start with one additive at a time.
2. Follow Supplier Usage Rates
Additives vary dramatically in strength and concentration. The recommendation for one product may not apply to another.
3. Watch for Extra Heat
Sugar, honey, milk, and some other ingredients can increase the heat produced during saponification.
This is particularly important when making cold process soap.
4. Understand What Goes Into the Lye
Some additives, such as Tussah silk and certain sugars, are commonly incorporated into or dissolved in the lye solution.
Others are better added to the oils or soap batter.
Don't assume every additive can simply be dumped into your finished batter.
5. Keep Good Notes
Write down:
- Your recipe
- Additive
- Amount used
- When you added it
- Temperature
- Trace
- Unmolding time
- Final results
This makes it much easier to improve future batches.
Can You Use Multiple Additives in One Soap?
Absolutely—but beginners should resist the temptation to create a "kitchen sink" soap with every additive imaginable.
A simple combination might be:
Sodium lactate + kaolin clay + colloidal oatmeal
This gives you a harder, easier-to-unmold bar with a silky feel and gentle oat addition.
Another combination could be:
Sugar + Tussah silk + sodium citrate
This focuses on lather, luxurious skin feel, and performance in hard water.
The key is to understand why you're adding each ingredient.
If you can't explain what an additive is supposed to accomplish, you probably don't need it in that particular recipe.
Final Thoughts
Additives are one of the most fun parts of soapmaking because they allow you to take a basic recipe and customize it for a particular purpose.
But you don't need a huge collection to get started.
If you're a beginner, I'd recommend learning these first:
Sodium lactate for hardness and easier unmolding.
Sugar for bubbly lather.
Kaolin clay for slip and a silky feel.
Colloidal oatmeal for a conditioning, soothing-feeling bar.
Polysorbate 80 for bath bombs and products where you need oils to disperse in water.
And if you're ready to take your soapmaking into luxury territory, Tussah silk is a fun additive to experiment with.
Once you understand what each ingredient actually does, additives become much less intimidating—and a whole lot more fun to experiment with.
The goal isn't to use as many additives as possible.
The goal is to choose the right additive for the result you're trying to achieve.
Related Posts:
Cold Process Soap for Beginners: Everything You Need to Start
Top 6 Highest Rated Books to Learn Soapmaking
Top 6 Most Affordable Oils for Soap Making & Skincare (Beginner-Friendly)
Melt and Pour Soap vs Cold Process: The Easiest Way to Start Soap Making
My Favorite Soap & Bath Making Supplies – Blue Dragonfly Handmade
Frequently Asked Questions
What is the best additive for beginner soapmakers?
Sodium lactate, sugar, kaolin clay, and colloidal oatmeal are all relatively approachable additives for beginners. Start with one at a time so you can learn how each affects your recipe.
What does sodium lactate do in soap?
Sodium lactate can help make cold process soap firmer and easier to unmold. It can also improve the handling characteristics of some soap recipes.
What is Polysorbate 80 used for in bath bombs?
Polysorbate 80 helps oils and fragrance disperse more evenly through bath water. It can also help reduce the oily residue that may otherwise be left on the bathtub.
What does Tussah silk do in soap?
Tussah silk is used in small amounts to give cold process soap a silky, luxurious skin feel and can contribute to a creamy-feeling lather.
Does sugar make soap more bubbly?
Sugar can help increase the amount of bubbly lather produced by a soap. However, too much sugar can cause soap to heat up, so it should be used carefully.
Does honey make soap better?
Honey can contribute sugars that encourage lather and can give soap a beautiful warm color. However, honey also increases the risk of overheating, so it needs to be used carefully.
Can I add milk powder to cold process soap?
Yes. Milk powders such as goat milk powder and coconut milk powder are commonly used in handmade soap. Because milk contains sugars, however, milk soaps can become quite hot during saponification.
What additive makes soap harder?
Sodium lactate and salt can both contribute to harder bars, although they work differently and should be used at appropriate levels.
Do I need additives in handmade soap?
No. A well-formulated soap made with properly selected oils, lye, water, and fragrance or essential oil can make an excellent bar without any additional additives. Additives are optional tools for modifying particular characteristics of your soap.
Can I use Polysorbate 80 in cold process soap?
Polysorbate 80 isn't generally necessary in ordinary cold process soap because the soap itself is already a surfactant system. It's much more useful in products such as bath bombs and bath salts where you need oils to disperse into water.
What's the most important rule when using soap additives?
Know what the additive does before adding it. Use a cosmetic-grade ingredient, follow the supplier's recommended usage rate, and test new additives in small batches before incorporating them into a product you plan to sell.
