How to Make Milk Soap from Scratch

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Drowning in milk? Have enough cheese and yogurt to last for more than a decade? It’s time to learn how to make milk soap from scratch!

After gardening, soap making was the first homesteading skill I learned. At the time, I was living in a Sacramento suburb, still dreaming of a place in the country. But I decided that learning how to make milk soap was a homesteading skill I could pursue even in the middle of the city.

My very first batch of DIY milk soap was, objectively, ugly. I semi-burnt the milk, blended until the mixture was too thick, and had to glop the soap batter into the mold, leaving the finished bars lumpy and uneven.

Even with these shortcomings, I was proud of that soap and became enamored with milk soap making.

If you have a dairy animal on your homestead, DIY milk soap is a good way to use up extra milk, and the resulting soap is wonderful for your skin.

But you don’t need to have your own dairy animal. You can make milk soap from scratch with simple ingredients from the grocery store. Soap making is a wonderful self-sufficiency skill that anyone can learn to do, even if your homestead is a small lot in town.

Over the years, my soap making vastly improved, leading to a small business selling goat milk soap and teaching soap making workshops.

Today I’m sharing with you my tried-and-true tips for making milk soap so that you can avoid all my newbie mistakes and make milk soap from scratch successfully from your first batch on.

Let’s get soaping!

Benefits of Milk Soap

So, what makes milk soap so special? Three words: fats, sugars, and acids.

It’s the milk fats that give milk soap its extra moisturizing oomph. These fats are left as “free oil” in the finished soap bar, making milk soap supremely gentle and nourishing to the skin.

The characteristic rich, creamy lather of milk soap can be attributed, mainly, to the sugars found in milk. Lactose, the chief sugar in milk, increases soap lather because it reduces the surface tension of water allowing bigger and longer-lasting bubbles to form.

Remember being a kid and blowing bubbles with a straw into a glass of milk versus a glass of water? Milk produced big bubbles that overflowed the glass and lasted a long time; water bubbles burst quickly. The same effect happens with milk soap versus non-milk soap—bigger bubbles that last longer.

Milk also contains naturally occurring hydroxy acids, specifically lactic acid. Lactic acid is a gentle exfoliant, and leaves the skin feeling softer and looking brighter. Milk soap isn’t at the same level as an exfoliation treatment like a scrub or peel, but it does give a little extra benefit for your skin.

What Kind of Milk Can I Use for DIY Milk Soap?

While goat milk makes the quintessential milk soap, any type of milk can be used including cow, donkey, coconut, and more. The soap making instructions below can be used with any type of milk you desire.

Fresh Milk

If you have a dairy cow or dairy goat, obviously you have plenty of fresh milk to create soap. Either pasteurized or raw milk can be used for soap making.

Store-bought fresh milk can be used if you don’t have a dairy animal. The milk you have in your fridge right now will do, although whole milk will give a creamier soap lather compared to low-fat varieties. Larger grocery stores will also have fresh goat milk in the refrigerated section.

If there is a local creamery or dairy nearby, consider purchasing your milk from them. Your support of small farmstead businesses is vital and incredibly appreciated.

Canned Milk

You can also use canned milk to make soap. If you use this option, dilute the milk first with equal parts water since canned milk is concentrated.

Vegan Milks

Are you vegan? There are milk soap options for you too!

You can use the instructions below to make soap with coconut milk, almond milk, or soy milk. The steps are the same. The finished soap bars will have a slightly different color and consistency than soap made from cow or goat milk but will be a lovely soap, nonetheless.

The Key to Beautiful Milk Soap Making

Here’s the secret to making lovely milk soap: freeze your milk prior to soap making.

This is the step I skipped in my first few batches, and why my milk soaps turned a funky shade of brown and had an off smell (old tires came to mind).

It doesn’t matter if you’re using farm-fresh, store-bought, or canned. Or cow milk, goat milk, or plant-based. Use only frozen milk when making soap.

Soap is made using a blend of oils, liquid (milk, in this instance), and lye.

Yes, my friend, lye is needed to make milk soap from scratch. Nothing can be substituted for lye in handmade milk soap recipes. We’ll talk more about lye and its use in just a bit.

When oil, liquid, and lye are blended together it triggers a chemical reaction called saponification. When saponification is finished, you no longer have oils, milk, and lye; you have soap.

First, the lye is dissolved in the liquid. As lye dissolves it generates heat, and fast. It can heat a liquid to above 200 degrees Fahrenheit in just a few seconds.

In water, that isn’t a problem (except, of course, you must be careful to not burn yourself). Bringing milk up to a high temperature so quickly will scorch and curdle, making it smelly, off-colored, and unusable.

Freezing the milk counteracts this, preventing it from becoming too hot too fast.

The most convenient way to freeze (and use) milk for soap making is to freeze it in ice cube trays. When you’re ready to make soap, simply pop the cubes out and place them into your container.

Don’t freeze the milk in its entirety as one solid mass. It’s nearly impossible to properly dissolve your lye granules in a big block of frozen milk.

Soap Making Safety Rules

If you’ve never made soap before, there are some lye handling safety rules you must know before you whip up your first batch.

But truly, there is no need to fear lye. If you have ever used a drain opener in your home, you’ve already used a form of lye.

Following these simple tips will help you craft your milk soap safely.

  • Use only 100% lye. Although you can find 100% lye at the local hardware store, it’s often safest for beginning soap makers to buy lye online from soap making suppliers. This way you’ll be certain to get the right lye for soap making.
  • Wear rubber or exam-type gloves and eye protection goggles. Lye granules, lye/milk solution, and soap batter are all caustic. To protect yourself, put gloves and safety glasses on at the beginning of your soap making and don’t remove them until after clean-up.
  • Weigh out all ingredients. Soap ingredients must be measured by weight, not by volume. Weighing ingredients gives a more precise measurement to ensure your finished soap is not lye heavy.
  • Clean up lye spills with copious amounts of water and mild soap. If you get lye granules, lye/milk solution, or soap batter on your skin, immediately rinse with cold water, wash with a mild soap, and rinse some more. For spills on countertops and floors, wipe up as much as possible with paper towels and discard (or sweep up lye granules with a broom). Wash the entire spill area with a damp rag and mild soap, such as dish soap.
  • Do not substitute oils in any soap recipe. Soap recipes are formulated with very specific lye-to-oil ratios. There needs to be just enough lye in the recipe to turn oil into soap, but not so much to leave lye in the finished batch. If you swap out one oil for another, you run the risk of creating a lye-heavy soap. Only experienced soap makers who know how to recalculate lye amounts should substitute oils.

Soap Making Supplies

You will need to gather a few supplies to get started making homemade milk soap.

Important note: Due to the caustic nature of lye, all the supplies must be used exclusively for soap making (so don’t use them again for food). You can, however, use these tools for creating other types of DIY bath and body products.

Easy Milk Soap Recipe

This recipe makes approximately 2 pounds of finished soap at a 7% superfat.

  • 14 oz. frozen milk of your choice (goat milk, cow milk, etc.)
  • 13 oz. olive oil
  • 9.5 oz. coconut oil
  • 9.5 oz. palm oil
  • 4.5 oz. 100% lye

Prep step: Gather all supplies and ingredients needed and have them easily accessible. Put on your gloves and goggles (remember, keep these on the entire time you’re soaping until after you’ve finished cleaning up.)

Step 1: In a measuring cup, weigh out each oil individually and add to the stainless steel pot. Place the pot on the stovetop and warm oils over low heat until melted. Remove from heat.

Step 2: Weigh out frozen milk cubes into the plastic pitcher. No need to cut or sh­­ave cubes to get a precise measurement for the milk. If adding an extra cube brings the measurement slightly over 14 oz., that’s okay.

Step 3: In the second measuring cup, weigh out lye granules. Do be precise with this measurement.

Step 4: Slowly pour the lye into the frozen milk cubes, stopping frequently to stir. The milk will immediately begin to melt. It will also change in color.

After you’ve added about half the lye granules, check the temperature of the lye/milk mixture. You want the lye/milk mixture to come up to above 85 degrees Fahrenheit but stay below 100 degrees. Higher than 100 degrees and your milk will scald and curdle; lower than 85 degrees and the lye granules may not dissolve fully.

Continue to slowly add lye to the milk, testing the temperature periodically. If the mixture is nearing 100 degrees, let it cool for several minutes before adding more lye.

Step 5: Once you have added all the lye to the milk, let the mixture sit for 20 minutes. This step is important as it gives the lye granules ample time to fully dissolve.

Step 6: Carefully pour the lye/milk mixture into the pot of oils. The lye/milk will have thickened considerably, so don’t fret if you come back to a pudding-like mixture. Use a silicone spatula to scrape as much of the lye/milk mixture from the pitcher as possible.

Step 7: Place the stick blender into the pot, making sure the bell is fully submerged. Blend in 30-second spurts until the mixture is fully incorporated and has thickened to a cake batter-like consistency (what soap makers call trace).

Step 8: Ladle or pour the soap batter into your prepared mold. The batter will continue to thicken, so be prepared. No need to rush, but don’t let it set in the pot any longer than needed. Use your silicone spatula to spread the soap batter evenly throughout, making sure it reaches the corners of the mold.

As a finishing touch, use your spatula or wooden dowel to make a pretty decorative texture on the surface of your soap.

Step 9: Set the soap mold in an out-of-the-way spot for 72 hours. This allows the soap to finish saponifying and firm up. I prefer to cover my mold, to prevent pets or accidental fingers from getting into the soap batter. If your soap mold doesn’t have a lid, you can improvise with a piece of cardboard. Don’t allow the lid to touch the surface of the soap. If your soap mold is so full that a lid will contact the soap’s surface, just leave the lid off.

Step 10: Clean up! Keep those gloves and goggles on, the soap batter on your tools is still caustic. Wipe any excess soap batter off your tools with paper towels or crumpled newspaper and discard. Wash everything well with dish soap and rinse. Wipe down your work area with a damp cloth. Once everything is completely cleaned up, it’s safe to remove your gloves and goggles.

Step 11: After 72 hours, your homemade milk soap is ready to unmold. Turn the soap out onto freezer paper or brown paper and cut it into bars. The soap will be soft and sticky, like soft cheese. It will harden during cure. Cut the soap into bars using a soap cutter or large non-serrated knife.

Step 12: Cure your soap for 30 days. Simply set your soap bars out on brown paper or freezer paper in a dry, out-of-the-way spot like a cabinet or closet. Make sure the bars are not touching each other to allow air to circulate around all sides. Turn soap bars once every week or so to expose all sides to air.

Curing is important, so don’t skip this step. During curing, any excess liquid evaporates out, creating a hard, long-lasting bar of soap.

After 30 days of patiently waiting, your soap is ready to use.

To store your milk soap: Wrap bars in paper or keep them in a paper bag or small box. Air circulation is important for long-term storage. When properly stored, your milk soap has a shelf life of 5 years.

Enjoy your homemade milk soap!

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