1. Castile Soap

my first batch: pure castile with lemon balm herb

© 2010 by KV5R — Rev. Nov. 24, 2010.

Shop for soap making supplies here.


  • Acquire soap-making skills.
  • Make a small batch of unscented pure castile (olive oil) soap.


  • I hate commercial detergent. It gets through my skin and I can taste it for hours. Yuk.
  • Allergic to lauryl/laureth sulphates used in most “skin care” products. Itchy.
  • Hypersensitive to most fragrances used in commercial products. Can’t breathe in the soap aisle, much less the shower.

Tools and Supplies Used

No endorsements here—this is just what I got and where I got it.

  • Digital kitchen/postal scale, Walmart, ~$20.
  • Stick blender, Oster 250-watt variable-speed, Walmart, ~$25.
  • Small dial thermometer, Walmart, ~$8.
  • Walmart GV Pure Olive Oil, 25.5 fl.oz, ~$4 (not Extra Virgin).
  • Roebic Crystal Drain Opener (100% Lye), 2 lb., local hardware store, ~$16. (See essentialdepot.com for lye and potash.)

Totals: Tools: $53; supplies: $20; supples used: ~$6 for ~32 oz. (907g) of soap (8 bars ~4 oz. (113g) each).

Already had:

  • 3 qt. SS pitcher (like restaurants use for serving ice water).
  • 2 cup Pyrex measuring cup (for mixing lye).
  • 4x12 rectangular Tupperware with lid (#892-4) — my on-hand loaf mold.


Don’t use it—keep reading!

  • 25.5 oz. bottle of olive oil (see “Oops!” below)
  • 8 oz. lemon balm herb tea, strained and cooled (waste of time: didn’t add any lemony smell to soap, but did make interesting marble pattern. Next time I’ll just use distilled water).
  • 3.30 3.02 oz. NaOH crystals, per MMS calc, 5% superfatting.


  • Made the lemon balm herb tea, about 12 oz. (boiled in microwave then whizzed with stick blender).
  • Strained and measured 8 oz. of the tea (on the scale) into Pyrex measure; set in freezer to chill.
  • Run sink 1/3rd-full of cold water.
  • Measure 3.3 oz of lye powder into very dry bowl on scale. Used too much lye.
  • Set Pyrex of cold tea in sink water (making sure it was not about to float or tip over).
  • Added lye to tea and mixed. Fumed for just a few seconds; not a problem. Temperature rose to 170°F (77°C). Should have started with colder water.
  • Put opened bottle of OO in the microwave for 1 minute. Rose to 120°F (49°C), no fire needed.
  • Poured warm OO into a 3-quart SS pitcher. Forgot to weigh it.
  • Let both caustic solution and OO cool to 115°F (46°C).
  • Poured caustic into oil and stirred a few seconds with SS spoon.
  • Inserted the stick blender, at a slight angle, and fired it up on lowest speed. Nice rolling churn; no air whip.
  • Light trace in about 1 minute. WOW! 30 seconds later it was thick pudding!
  • Poured, scraped and patted into 4x12-inch Tupperware.
  • Popped on the lid and wrapped it in a towel.
  • Clean-up: hot water and dish detergent in the SS pitcher. Whiz it with the stick blender. Finish up with soapy sponge and then rinse well.

Total time: about 30 minutes, including clean-up. Conclusion: It was a whole lot easier and faster than expected. This would have taken several hours without the stick blender (olive oil is notoriously slow to trace by hand).

About 5 hours later, I unwrapped it for a peek. White at the corners, and a white film on top. Most of it is gel. Looks like I made a fine batch of axle grease! Oh well, we’ll see tomorrow.

Tomorrow: Solid but not crumbly; soap brick popped right out of the polyethylene Tupper. Cut easily with a cleaver, like a medium-firm cheese.

So how does it work? Washed hands with shavings. Mild, very little lather, rinses easily. But nowhere near as nice as Dr. Bronner’s liquid castile. I guess I’ll make a new and better batch!

What Went Wrong

  • Oops! I forgot to weigh my oil! I just used 25.5 on the bottle, but that’s fluid ounces. Looking up the specific gravity of olive oil, .92, that means my oil weighed 23.46 oz. Plugging that weight into the MMS calc, I should have used 3.0 oz. of lye, not 3.3. No wonder it full-traced in 1½ minutes! Oh well, I have some slightly caustic soap.
  • Next day I decided to rebatch it and add 2-oz. more oil, but didn’t know what I was doing, and messed it up. Now it’s a spongy goop.
  • Using herb tea for the caustic mix was a bad idea. Should have used distilled water and added powdered herb during trace.
  • Should have used colder water. Took too long for the caustic to cool down from 170 to 115. Had to reheat the oil twice.
  • Didn’t know that 100% olive oil makes lousy soap. Too soft, and almost no lather. That’s what coconut and palm are for!


Sorry I didn’t get any during the process, but who wants to handle a camera and lye at the same time? These pictures were later staged.

lye and oil containers

water in cup in water in sink
Water in Pyrex in Water in Sink (saucer keeps cup stable)

bowl on scale
Tare the bowl…

weighing the lye
Weigh the lye… Now cap it!
Collect any stray crystals with a damp sponge, then sink it.

pouring lye into water
Dump the lye in the water…

mixing the lye
Stir… This is when it will heat up and fume for a few seconds.
Notice the bowl, with a few clinging crystals, went straight into the sink water.

checking the lye temperature
Watch the temp. This didn’t heat up because I used just a little lye for the picture.

I’ll get pictures of the oil/caustic mixing on the next batch. Stay tuned!

Soap and tools
There’s everything all cleaned up.

Soap bars with marble pattern
It marbleized itself! Something about the herb tea…

Shaved soap
Later, after rebatching with a little more oil, I shaved it (with a Salad Shooter) so I can use it for laundry.

So there you have it, my first botch—er, batch. If this inspires you to jump into the soap hobby, please see the other pages in this article, and the more detailed sites that are dedicated to soaping. There’s a whole lot more to learn than I have presented here—things like properties of various fats and oils, fragrances, rebatching, swirling colors, fancy molds, and most of all, what to do if a batch goes wrong.

I’ve ordered some coconut and palm oil, and a silicone mold (Crafters Choice 6x 6.5-oz squares). When that comes in, I’ll make a proper batch of classic 3-oil, and get more pictures and post the results here. Stay tuned!

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