3. The non-ionic detergents. These do not have a specific charge, but the hydrophilic (water-soluble) portion of the molecule is usually achieved by incorporating a polyethylene oxide group into the molecule that polarises this section of the molecule to be slightly negative. However, because each oxygen has less charge than an ion, the hydrophilic portion of these molecules is bigger than in the case of the ionic surfactants. They are low foaming and so are useful in front loading washing machines and dishwashing machines.4. Finally, there are some specialised products that carry both a positive and a negative charge in the same molecule. These are called amphoteric surfactants.