Hot Process Soap Making Part 1



I’ve been making soap for about 6 years and I still find the process absolutely fascinating.  I can’t explain all the science behind it, but it’s just amazing that water, having dripped through wood ash, becomes so volatile that when combined with oil it becomes a completely different product.  Is that amazing to you too?

Hot process soap making is a simple, but exact, science.  While there is room for creativity here and there, it IS a chemical reaction we’re creating and the percentages of lye, water and oils necessary to make that happen are EXACT.  To have a successful experience every time, you have to create those same exacting conditions every time or you’ll find soap making to be a frustrating, expensive waste of money and time.   Now there are 2 methods for soap-making; cold process and hot process, and they’re nearly identical except for the manner in which the soap is “cured” to neutralize the lye.  I’m going to show you the hot process as it’s much quicker and will be ready in time for gift giving if you choose to do so.  I’m also going to break this post into 2-3 parts so you can absorb the information without feeling overwhelmed and giving up.

There are essentially 4 steps to soapmaking.

  1. Carefully mixing distilled water and lye, in which the chemical reaction results in a steaming hot solution, and then allowing the solution to cool to 100 degrees F.
  2. Heating/melting of a combination of oils and solid fats, typically grapeseed, olive, almond and coconut oils.
  3. Combining the lye solution and warm oils and mixing to the point of ‘trace’, where the solution becomes pudding-like and thick enough that strings of soap form on top of the solution.
  4. Curing, either by heating the soapy mixture (hot process) or allowing the mixture to sit in a warm spot for 6 weeks for the lye to neutralize (cold process).

No matter how elaborate the recipe may seem, soap making always comes down to those 4 steps.  Always.  So if you’re anxious to try your hand at making soap, kinda wrap your mind around that.  Set the rest of the information aside and familiarize yourself with those 4 steps.

Okay, now there is some equipment that you’ll need that has to be set aside exclusively for soap making.  You absolutely do not want to serve popcorn in your big soap making bowl or use the same utensils for cooking.  Hit up the dollar store, my friends.  You can find most of what you need there for a few bucks.

Necessary equipment for soap making:

  • An assortment of plastic bowls for measuring ingredients.
  • Plastic spoons and spatulas for mixing.
  • An immersion blender, optional, but SOOOOOO highly recommended!  Trust me on this one.
  • A scale that can be zeroed for weighing oils, lye and water.  The vast majority of recipes are based on weight, not volume, so a scale is an absolute necessity.
  • A candy-making thermometer.
  • Non-reactive molds.  These can be anything from a shoe box lined with parchment paper to silicone bread pans.  Personally, I like the silicone molds and pans.  They’re easy to clean and easier to remove the soap from than other molds.
  • Old towels.  Everyone should have these laying around!
  • Safety gear.  Dishwashing gloves, safety goggles, a face mask and an apron/smock.
  • Something to dry the soap on/in.  A plastic storage container lined with plastic canvas works great.
  • A plastic tablecloth.  You’ll want something to cover your workspace, preferably waterproof.
  • A gallon of white vinegar.  In an accident, vinegar will neutralize the lye immediately preventing burns.
  • An old crockpot.  For hot-process soap, you need something to heat the soap for 1 hour.  This speeds up the saponification process (conversion of oil+lye into soap).  You won’t want to use it for cooking afterwards, so check into a thrift shop for an inexpensive model that you’ll use solely for soap-making.

I know that looks like a lot of stuff but much of it is laying around your kitchen right now and it can be used indefinitely.  And as I stated, much of it can be found in bargain bins, so the initial investment should be fairly minimal!

Here’s how you do it!!

Gear up.  You’re going to feel a little silly walking around your house in a haz-mat suit, but it’s totally necessary to cover your face and exposed skin.  Lye can cause burns very easily and it stinks when combined with water, so the full suit is a must!

Step 1. Preparing the oils.

With very few exceptions, the recipe you choose will include a combination of solid and liquid oils.  Typical solids are lard, coconut oil, cocoa butter and even vegetable shortening.  Typical liquid oils include anything from olive oil, grapeseed oil, almond oil, avocado oil to plain old run-of-the-mill vegetable oil.  Don’t go renegade here!!  Be sure you choose the exact oils your recipe calls for, as the lye requirement to convert oils to soap vary.  Most recipes will give you an option of oils to choose from that fit within that required range.  Stick with those so you don’t end up with a soap-making fail!!   Using your zeroed scale, carefully weigh the precise amount of solid and liquid oils and put them in your crockpot on low heat to melt the solids and heat the liquid.  (Be sure to scrape every last bit of weighed fat out of your bowls…precise measurements, my friends!)

Step 2. Preparing your lye mixture.

After the solid oil has begun to melt, zero your scale and using a small plastic container, weigh the prescribed amount of lye.  Set aside.  Again, using a plastic container, zero out the scale and carefully weigh the distilled* water.  Precise measurements are necessary, so pour slowly and watch the scale carefully.  Very, very carefully add the lye to the distilled water.  (Never add the water to the lye as the solution can splash and cause a bad burn.)  Within a second or two of adding the lye to the water, you’ll notice a chemical reaction with extremely hot, steaming water and a foul odor.  That’s totally normal.   Immediately begin stirring the lye-water mixture with a plastic spoon until you no longer see lye crystals in the water.  That shouldn’t take terribly long, a minute or less.  Now you need only to set the solution aside and allow it to cool to 100 degrees.  Personally, I do this step outdoors so my house don’t stink, but no matter where you do it, place the cooling solution in a spot where children and animals can’t access it.  This is serious, y’all.

*Distilled water is a necessity as tap water frequently contains heavy metals, minerals and chlorine which can effect the chemical reaction and result in a “meh” colored, odiferous soap.  You should be able to buy a gallon of distilled water for under a dollar.


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Okay friends, I’m going to stop here for today.  To this point, we’ve collected the necessary equipment and created the 2 solutions that we’re going to mix together to create lye soap.  The hard part is finished, if you want to call that the hard part!   Reread the information carefully and please feel free to ask me any questions you may have thus far.  In Hot Process Soap Making Part 2, we’ll combine the mixtures, add some pretty additives, finish the soap hot process-style and mold.  So far, so good, my sweet friends!  Til next time!


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