Adding Food to Soap -a Guide for Soapmakers

Modified from Kandra’s original post on Soapmaking Natural Ingredients Forum

Soap makers seems to always think “hrmmm I wonder if I can soap that”, especially when it comes to “food-stuff”. Maybe it’s because soaping and cooking are so similar? 🤔 hmmmmm… Can we (and should we) add things like fruits, veggies, teas, juices, herbs, etc. to our soaps? The TLDR is, heck yes! We’re soapers, let’s soap it! But really, let’s see what happens if we do, and talk about what it brings to the soap (including coloring soap naturally!)

Let’s start with the “why” when it comes to adding Food to Soap

Let’s start with the soapy elephant in the room. No one really knows whether beneficial properties of anything you add to soap survive saponification.  Most of what I’ve been able to find is based on anecdotal evidence.  Without some scientific testing I don’t really know if the skin-soothing property of aloe vera will  survive the lye monster but I can tell you from personal experience that it appears to (along with the astringent properties of cucumber.)

We do have one study that we should mention. It shows that the natural antioxidants from wild berries improve the shelf life of natural soaps!

Anecdotal properties aside, adding these ingredients to soap can have some real benefits:

• Bubbles
• Creamy lather
• Amazing natural colors
• and even exfoliation.

And now for the “when” and “how” (aka how much to use, and when to add it) when putting food in soap

Typically, I add everything to my oils. This prevents the “grrrr I forgot” moment after you’ve already added the lye solution. It also eliminates the issues of scorching if using the additives to dilute the lye. Not to mention that you never have to guess if all of your lye was dissolved in your milk (or juice, or beer, etc.)

Here’s a quick run down on how I make soap:

1. Measure oils and butters into the pot. Give it a blitz with the blended to make sure there are no giant clumps of butters or solid fats. I typically don’t warm my oils (but there’s always the exception).
2. Mix my lye solution or measure out from my master batch if I’m in a big production swing.
3. Add any extras to my oils – be it milks, purees, essential oils and clays, or even extra water.
4. Double check everything.
5. Add lye solution and make soap!

I’m just imaging goat milk soapers cringing at this. Wondering why on earth I would use water when I could be using goat milk! Well, I never said my way is the only way, did I? Nope! We’ll chat more about milk in a moment, but first, let’s chat about my lye solution:

The minimum amount of water needed to make soap is 1-part water to 1-part lye (1:1).  This is necessary to dissolve all the sodium hydroxide prior to safely adding it to your base oils.  Aside from that, any additional water (or juice, tea, etc.) is up to the soap maker.  Just keep this in mind when formulating the “water” for your recipes:

• Adding too much water (in my experience anything over 1.75:1) to cold process soap will generate more heat that you need. You’ll end up with volcanos, heat tunnels, alien brains, and soft soap.
• In hot process this extra water can be a great tool to speed up the saponification process, help with fluid batter, etc. But you can also add extra fluids after the cook (like juices and milks).
• When working with liquid food-stuffs, like milk, keep in mind that the amount of “water” in your liquid is less than the amount of liquid you measure out.  Meaning: 100g goat milk does not have 100g of water which is needed to dissolve 100g lye. This means you might need 2:1 milk/lye to safely dissolve all the sodium hydroxide. (or you can do it like I do, and just add the milk to the oils 😉).

Ok, with that said, here’s the “how” and “when” for various food-stuff that you can add to your soap… along with some additional “whys” for each type:

One more note though: These are guidelines and as such, you can break them.  Some ingredients will allow you to use more, while some would require much less.

Making Soap with Vegetable or Fruit Purees

Why?  If you’re like may soapers, “because you can,” might be your honest answer.  Then you realize that these can have wonderful effects such as boosting bubbles, color and design, silky lather, astringent effects, silky glide, and more.

When?  Add these to the oils before you add the lye water.  This helps ensure that the organic material is evenly dispersed throughout the batch and helps avoid scorching the material with the lye water.

How much to add:  I’ve had great luck with 100g puree to 1000g of my base oils.  Looking back on my notes from previous batches, I have had success with this general ratio with bananas, carrots, and cucumber. Here’s exactly what I do:

• Measure oils.
• Mix lye solution.
• Pour off a few ounces of your oils and blend in with your puree to make a puree slurry
• Add the slurry to your oils before adding your lye solution.

You should also check out this article by Kevin Dunn on Using Food in Cold Process Soap.

Adding Teas (or brewed coffee) to Handmade Soap

Why?  Color (mostly brown, but some others,) label appeal, possibly other benefits (based on anecdotal data.)

When?  Typically added to the lye water as a full or partial water replacement.

How much to add:  Typically, a full water replacement, meaning, you dissolve your lye directly into the tea.

A note on coffee grounds and tea herbs: using these can make the soaps scratchy, but some people are going for that. (see adding non powdered food-stuffs below). Coffee grounds should be wet when added (i.e. make some coffee first) to avoid glycerin rivers or coffee stains around the grounds. I typically strain out herbs as they can have the unfortunate appearance of “junk in my soap”. Now, I say typically, but here’s a soap with the herbs only mostly strained out, and the little specks are beautiful (and not scratchy).

Adding Beer and Wine to Handmade Soap

Why?  Bubbles (lots of bubbles from all that lovely sugar), color (mostly tans), label appeal (what beer lover wouldn’t want to take a beer into the shower?), and aroma (more info on that here).

When?  Can be added to the lye water as a full or partial water replacement or added to the batter at emulsion.

How much to add: You can use beer or wine as your full water replacement but be warned that it will trace FAST. I recommend that you use a 1:1 water:lye solution, and then add 25-50% of the water weight in wine or beer to the batter.

Here are a few other tips, and my process for adding beer or wine to soap:

• First: Boil down the beer/wine to remove any carbonation and evaporate the alcohol.
• If using for the liquid to dissolve your lye, freeze your beer/wine first.
  • Slowly add the lye to the frozen beer/wine. You might also consider using an ice bath for your lye pitcher to help keep things cool and avoid scorching.
  • Have your oils ready and mold, this will go fast.
  • Add lye to oils, make soap, and be ready to mold asap.
• If adding to the soap batter (my preferred method) cool to below room temperature. I usually just pop it in the refrigerator after boiling and make soap the next day.
  • Make your 1:1 lye:water solution. And add to oils. Bring to emulsion.
  • Add your chilled beer/wine and blend well. I usually do one or two pulses with the stick blender, hand mix for 30 seconds, and then mold. Results will vary based on your beer/wine and oil mix.

Using Non-Powdered Food-Stuffs in Natural Soaps: Coffee Beans, Oats, Flower Petals, Grains, Dried Citrus Fruit, Seaweed etc.

Why?  Color, exfoliation, decoration, aroma, label appeal, and more

When?  You can add herbs to either the lye water, or the oils, or as toppings to decorate your finished soap loaf.

• When adding to the oils, you will end up with particles of herbs dispersed throughout your batter.  This could be for exfoliation or just design.  Consider grinding them up a bit first to avoid large chunks of “stuff” in your soap.
• You can also infuse the oils with the herbs and then strain the spent organic materials to avoid plant particles in your soap.
• When adding to lye water, you are basically making a strong tea as the lye heats up the water and “brews” a tea for you.  Strain your lye water before adding to your base oils to avoid chunks of “stuff” in your soap.

How much to add:  There is a HUGE range of answers for this.  I have specific notes in my formulary book for various items, and it’s all based on experience.  I started with eyeballing it, then started weighing and taking notes.  The main things you need to consider:

• When topping as a decoration, consider how it will fall off (or scratch) when the soap is used.  Some items (like lavender or whole oats) may look off-putting after the soap is cut. Things will turn brown and some might mold so use your discretion when dressing your soap.
• Exfoliation is good, scratchy and “micro tears in the skin” are not.  Be light-handed on the coffee grounds.

Powdered Food-Stuffs in Natural Soap: Cocoa powder, turmeric, paprika, etc.

Why?  Color, exfoliation, decoration

When?  Typically added to the base oils.  You can simply sprinkle into your oil container and blend away, but I prefer to add a bit of oil or water to the powder, blend to a slurry and then add that back into the base oils.  This helps prevent clumps in my full batch of oils.

• If using as a colorant, you can add a bit of your oils or some extra water, to make the slurry.  Set this aside.  
• Add your lye solution to your base oils and emulsify (not quite to trace.) 
• Divide your batter and add your color slurries.  Your divided batters will come to trace as you are mixing the colors in.

How much to add:  As with non-powdered materials, this answer varies based on what you are adding.  A good starting point is 1 tsp PPO (per pound of oil) up to 1 tbsp PPO.  Just keep in mind that the more you add, the higher the chance of colored suds (chocolate brown soap lather isn’t the most appealing way to shower).

Making Milk Soap: Cow milk, Goat milk, Coconut milk, Oat milk etc.

Why?  Amazing lather (bubbly and creamy), and great skin feel.

When?  As a water replacement for your lye solution or as an additive to your oils.

• When using as a water replacement, freeze your milk first.  This prevents scorching the fats in the milk.
• If you do not want to freeze your milks, use a 1:1 water/lye solution and then add your milk to either the lye solution or to your base oils.

How much to add:  This is another “it’s up to you!” answer.  Here is some guidance for your journey:

• You can do a full water replacement with milk, just keep your milk/lye ratio to at least 1.5:1 (see note above about water content in your formulations.)
• If you’re using water to dissolve your lye, use 1-part water to 1-part lye and then add no more than 1 additional part (by weight) of the milk.  Anymore and you may run into volcano issues (see note above about water content in your formulations.)
• If your milk is in powder form, see above about powdered food-stuffs.
• Milks (due to their sugar content) tend to heat up the saponification process.  Freezing your milks first helps, as does soaping at room temperature.  Some also put their soap in the refrigerator to slow things down and prevent a partial gel.  This is all to prevent overheating that can result in darker soap, volcanoes, and alien brains.

Adding Yogurt to Cold and Hot Process Soap

Why?  Just like milks, yogurt adds an amazing lather (bubbly and creamy), and great skin feel. In Hot Process soap, it also helps create a fluid batter!

When? 
For cold process, use as a water replacement for your lye solution or as an additive to your oils. Just like with milk, you can use yougurt as a water replacement for your lye solution. Remember to freeze is first to prevent scorching. I don’t like this method and just use a 1:1 water:lye solution then add yogurt to the oils.

For hot process soap fluidity, add the yogurt after the cook (along with your superfat and fragrances).

How much to add:  1tbsp per pound of oil.

Honey and Sugar in Handmade Soap

Why?  These will really boost your bubbles!

When?  

• For honey: Make a slurry with some of your base oils, then blend the slurry into your base oils. This helps ensure that the honey is fully dispersed.
• For sugar: make a simply syrup and add that to your oils or lye solution (a simple syrup is just dissolved sugar in water)

How much to add:  Typically 1 tsp PPO.  Anymore and the sugars will heat up your soap which could result in a volcano.

Salt Soaps

To do salt justice, I will eventually write a full post on it but here is a super quick run-down:

Why?  It adds hardness to bars and boosts bubbles in hard water.

When?

• If you are looking to make a full salt bar, add the salt to the batter after emulsion.
• If you are making a brine bar, dissolve the salt in the lye water.

How much to add:

• For a full salt bar, add up to 100% weight of your base oils.  You will want to pour your soap into cavity molds as you will not be able to cut a full salt bar.
• For brine bars, I add about ½ tsp of salt per PPO. You can use anywhere from 1 tsp ppo up to 20-25% (of water weight) of salt. 

Egg Soaps

Why? First note that you can add either the whole egg, just the yolks, or just the whites when making egg soap.

• The yolks contain about 5 gr of fat and help make a rich and creamy lather. Here’s the fatty acid profile for egg yolks.
• The whites do not have any fat, but they do have protein that has an astringent effect on the skin. I made a cucumber, charcoal, and egg white soap years ago. It was way over the top and felt like I had a face lift for the day, yikes!

When? To avoid scrambled egg soap, you are going to want to temper your eggs into your oils. This applies for the full egg, just the yolks, or the whites.

• To temper your egg, simply blend in a portion of your oils into the egg. Then, add that back into your base oils before adding the lye solution.
• You’ll also want to soap cooler (around room temperature, up to about 110 degrees).

How much? Add 1 egg (or yolk, or white) PPO for your formula. Note that the egg yolk adds about 5gr of fat, and the white adds about 30gr of water. You should adjust accordingly by either reducing your calculated supper fat (for the yolk) or reducing the water used in your lye solution (for the white). I typically soap at a low water:lye ratio, so the extra water from an egg white doesn’t throw off my formulas in a negative way. I do tend to soap at a higher supper fat, so when adding egg yolk I calculate for about a 4% supper fat and then let the egg yolk account for more.