To remove makeup residues, even waterproof ones, we recommend soaking your reusable cotton pads in stain remover for about twenty minutes before putting them in the washing machine, on a hot cycle (temperature equal to or above 60°C).
If despite this they remain stained, you can try the following instructions:
Mix 2 tablespoons of baking soda, 1.5 liters of warm water, and one tablespoon of white vinegar;
Soak the makeup remover pads in this mixture overnight;
The next day, wash them in the machine at a temperature equal to or higher than 60°C.