Homemade Castille Soap (Laundry Bar)

This recipe is used for making laundry detergent and for a laundry stain bar. The directions are for cold process soap in general. This is the process and safety tips I use and they work well for me. You may find more understandable instructions elsewhere on the web.

Clause: I am not responsible for any accidents or injuries resulting from the use of these soap making instructions. Make soap at your own risk. Please be careful and responsible.


olive oil 14.4 oz

palm oil 1.6 oz

water 6.08 oz

lye 2.07 oz

SOAP MAKING DIRECTIONS (these instructions can be used for any cold processed soap making recipe);

Measure out all ingredients prior to making soap. You will need a small digital or manual postal type scale.

Heat oils in pan on stove to reach 110°.

Mix water and lye:

  • NEVER use aluminum or metal container or utensils to mix lye. Use plastic or glass container and wooden or plastic utensil.
  • NEVER add lye to hot water. Always use COLD water, the colder the better.
  • NEVER ad water to lye, this can have “volcano-explosive” effects. Always add lye slowly to water while stirring gently (and ALWAYS mix in a well ventilated area or outdoors).
  • ALWAYS keep a spray bottle of vinegar on hand. This can be used as a neutralizer for the lye in the event of burns.

Let lye mixture cool to 85°-95° (You may immerse the container 1/2 way into a cool ice water bath in the sink. Make sure you don’t get any of that water in the container and make sure the container is stable and will not tip or spill.)

Place pan of oils on a sturdy surface. Once lye has cooled to temperature, slowly pour lye/water mixture into soap mixture, while blending with an electric stick blender. (You can also stir by hand but it will take much, much longer. I have not personally done this so I can not tell you the time frame.)

Watch for “trace”. Trace is when the soap mixture thickens to a thin to medium pudding consistency and when you lift the blender and drizzle soap it will leave a “trace” of drizzle in the mixture. You will also notice the top getting shiny.

At this time you will add your pre-measured additives such as fragrance (or ground oatmeal etc. when making bath soap. NOTE: The above recipe is not for bath soap although it could be used as such but produces very little suds.)

When it reaches regular pudding consistency, it is done.

Pour into prepared, lined molds. I prefer large cigar boxes, or you can use any stiff cardboard box. I line them with freezer paper as if wrapping the inside of a present. It takes some practice but works quite well.

Place soap away from drafts and cold. Some prefer to wrap with a towel or small blanket. I just put mine in the oven with the light on. (no heat.)

Let ‘cure’ for 24-48 hours. Most soaps take only 24 but this soap may take longer. You want to make sure it is still soft enough to cut into bars but not so soft that it will be runny in the middle. If you can very easily put a finger indent in it, I would leave it sit a while longer.

Once set, remove from mold, and cut with large knife into equal size bars. (A good size for bath soap is 3 1/2″ x 2 1/4″ x 1″ or you can make round ones by pouring your mix into a cleaned out Pringles potato chip can, no lining necessary, when ready just peel off can and cut soap. For laundry soap I like to make them about 3″ x 1 1/2″ x 1 1/2″ which can be grated for laundry soap and also used as a stain stick (just spray water – or TKO cleaner- then rub on soap bar.)

Stand your cut bars on end on cardboard box or flat surface with space in between the bars. Keep in well ventilated area. This allows air to circulate and finish drying the soap. If necessary, label box with date and soap type. Turn soap over after a week or so. Let soap cure for about 2-4 weeks before using.


  • make sure there are no lumps in your soap and that it is not grainy. if so, you may need to heat up the soap some to remedy this.
  • Lye is a dangerous chemical and can burn your skin and eyes. Always wear rubber kitchen type gloves and goggles.
  • When mixing lye, keep the room well ventilated or mix outside if possible. Fumes can be harmful.
  • Do not make soap while toddlers and small children are close by. It is best to make soap during their nap times or when they are not at home.
  • Again: Keep vinegar handy. Vinegar neutralizes lye.
  • Again: Add lye to (cold- never hot) water, Never add water to lye.

Enjoy your soap! Your laundry! and the clean!