Bring 4 cups of filtered or distilled water to a boil.
While the water is still boiling on the stove, add 1 cup salt to the boiling water. Mix well until the salt is completely dissolved.
Take the water and salt mixture off the heat and add 1.5 cups of super washing soda to boiling water
Mix the really hot water, super washing soda, and salt until it is dissolved. If you have one, it really helps to use an immersion blender for this. You want to be sure to break up any clumps. If not mixed thoroughly, you can have little hard "rocks" in your detergent.
Let the salt, washing soda, and water mixture cool a little bit, then add 100 drops of essential oil (this is 1 tsp of essential oil).I used 50 drops lavender essential oil and 50 drops lemon essential oil.But lots of other essential oils and EO combinations would also be great. Here are a few others to try:100 lemon70 lemon and 30 tea tree40 lemongrass, 30 lavender, and 30 eucalyptus40 lavender, 30 lime, and 30 spearmint40 grapefruit, 30 orange, and 30 lemon30 spruce, 30 tea tree, and 40 cypress
use 1/4 cup for HE (high efficiency) front-loading washing machines or 1/2 cup for traditional top-loading machines
yields: 64 loads in HE machines, 32 loads in top-loading machines
You may want to keep a long-handled wooden spoon by your detergent. Over time, the washing soda and salt may settle to the bottom of the container and you'll need to stir (or shake) the container to remix.