For anything to do with making natural cosmetics or homemade cleaning products, I recommend that you use dedicated equipment that will be disinfected with alcohol before each use (to ensure optimal conservation of your creations).
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You can add half a cup of white vinegar per machine for delicate laundry (e.g. wool).
Baking soda and its miracles
Baking soda is an anti-limescale, softening, fungicide and deodorizing agent. You can insert one or two tablespoons of baking soda directly into the washing machine drum. However, be careful: baking soda is biodegradable as long as it doesn't reach a temperature of 60°C, otherwise it turns into sodium carbonate (also known as soda crystals), which has the disadvantage of not being biodegradable.
Alternate detergents
Note: if savon de Marseille is ideal for your laundry, it has the disadvantage of clogging your pipes over time because of the glycerine. I therefore recommend alternating your washes with an Ash detergent to preserve the durability of your machine.