How to make Hot Press Soap

 Hot Press Soap

I’ve been using melt and pour soap for awhile now and enjoyed adding my own essential oils and add in’s to make great smelling good for your skin soap. It was fun for awhile…but the crafting junkie in me wanted more… I knew their was something more out there, more crafty, and yes…more dangerous. Making soap…real soap with Lye, I would make it from scratch and know exactly what was in it, and it would be satisfying and glorious!

I took the advice of bloggers before me and did my homework. Google it….Pinterest the heck out of it! Read about working with Lye and decide if you are comfortable with that. I did all of the above and still wanted to do it even more so…well, because it mixes two of my favorite things, crafting and science.

Working with Lye:

  • Use a Lye calculator, this is a must! no matter how trusted the recipe, even ones I post, mistakes can happen when writing a recipe so just be safe and run it through the calculator.  It will tell you just how much Lye and water to use for the oil mix you are using. it will also allow you to make your own recipe based on what oils you have on hand or would like to use.


  • Respect The Lye. When handling lye, Protective gear is a must, gloves, long sleeves, Eye wear or goggles, in a well ventilated area or outside. No kids or animals around. Have a spray bottle of Vinegar near by, it neutralizes the lye if any should spill. When I’m done working with the Lye I spray down my whole work area with vinegar just to be sure. I also keep a sink full of soapy vinegar water to toss utensils into as I finish with them, even disposable ones to make sure they are safe to throw out.

So now that’s out of the way, let’s have some fun making soap!


Fat Amount
% in
Castor Oil 2 2.56
Coconut Oil 16 20.51
Olive Oil 30 38.46
Sunflower Oil 30 38.46
Total Weight 78

Lye                       10.68 oz

Water                   27 oz

Essential oil          1 oz  (for blending in just before it goes in mold.)


The thrift store is a great place to find supply’s for cheep if you don’t have some of these things, I just happen to have an extra ceramic insert to my Crockpot so its dedicated to soap and candle making.


Stick blender

Food Scale



Old long sleeve shirt

Bowls or containers (for measuring out oils, water & lye)

Soap mold (you can buy fancy, or line a box with parchment paper and cut into bars, I use a silicone loaf pan)

Spray bottle filled with vinegar

Step 1

  • Gather all your supply’s, and run your recipe through the lye calculator.
  • Using your scale weigh out all your oils first. (I have a digital that I can weigh my bowl first and reset my scale to 0, if you don’t have this feature you will need to weigh your bowl first and subtract that weight from your total number. The weight of each oil needs to be exact.
  • After you weigh your oils you can go ahead pour them in your Crockpot and place on low.

Step 2

  • Weigh out your water, and place in a heat safe container (you will be adding your lye to this, ALWAYS add the lye to the water, NEVER the other way around a very dangerous reaction will occur.) I use a half gallon mason jar.
  • If doing this inside, place container with measured water in the sink and open window and or turn on fan.
  • Put on all your protective gear and have your spray bottle of vinegar near by(just in case of spill, vinegar neutralizes Lye. lay out newspaper under the scale just in case and carefully measure out your lye. I have a double sink so my Lye water jar is on one side and I have soapy vinegar water on the other side so I just toss my dirty items into it as a go.
  • Slowly pour your lye into the measured water, and give a careful stir just to mix, then walk away, you don’t want to breath the fumes, give it 10-15 minutes, it will heat up and start to cool down in that time frame.
  • With your protective gear on, carefully pour your lye water into the oils in your crockpot, put anything that touched the lye into your soapy vinegar water. Then use your stick blender (not turned on) to give a good stir first, then turn on stick blender for a minuet or so, then turn it off and use it to hand stir, go back and forth like this with using the blender and hand stirring (you could just use the stick blender the whole time but it will burn up the motor on your blender) until you have reached trace. Trace is when it looks like thick pudding and if you drizzle some of the mixture on top of it’s self it stays on top without melting back in right away. This could take less then 5 min or 15 + depending on the oils you use.

Step 3

  •       Now that you have achieved trace, put the lid on the Crockpot and set the timer for one hour.
  •       Package up and safely store any remaining lye. Spray down your work area with vinegar (just to be safe)
  •       Remove your safety gear, and you can use this time to clean up, ready your Essential oil and or add ins.
  •        Prep your molds, if not silicone, line with parchment paper.
  •       Your soap will cook and bubble up around the sides at first then claps in on its self, I don’t stir it while going through this process unless it looks like it will bubble out of the Crockpot, then a small stir is just fine to keep it in. never leave it unattended, or you could have a mess.
Look! I'm making soap!

Look! I’m making soap!

Step 4

  • After an hour, it should all look cooked (see pic) if not you can go a bit longer just watch carefully.
  •  Give it all a good stir.
  • The timing of your add in’s is a little tricky, you want your soap to cool a bit so it does not burn off the scent, but hot enough to get in the mold.
  • When the timing is right stir in your Essential oil, stir it good, and spoon into mold.
  • Let set in mold 24 hours before removing, or I put mine in the fridge for 2-3 hours if i’m impatient.
  • Take out of mold and, If using a loaf mold, cut your bars in desired size, and stand on end to finish curing.
  • You can use a bar right away it’s fine to use but you want them to get nice and hard.
  • If I wrap them at all, I use paper so they can continue to cure and harden.
Hopeshomemade Soap

Hopeshomemade Soap

TIPS: When you are taking the soap out of the Crockpot, I like to divide it into smaller bowls so I can experiment with scents and add in’s.

Look for more recipes to come with fun add in’s, scents, and color…and how to get fancy with it!

Love Hope

If you enjoyed the science of making soap, check out my reasons for making wine! Hope’s top 5 reasons for making wine