Water is a great solvent. It’s neutral and doesn’t provide any strong positive or negative effects. It just helps components to mix better and to transport active components.
Dimethicone is the most popular silicone. It makes the skin softer and forms a film adding smooth and silky feeling. This film not only improves how the skin feels but also works as a protective barrier. It also improves the visual appearance of your skin by filling small wrinkles. What you should really know is that this component is difficult to wash off! So make sure you did proper cleansing after using it.
Butylene Glycol is a very popular synthetic alcohol. It helps the product to absorb deeper and faster. It is also a solvent for other ingredients. As for the skin benefits, it helps to attract water and helps to make the skin softer.
Unlike many other “Glycols”, it is not harmful and that's why it is used in many products. It was approved by US FDA and US EPA for usage.
Betaine is used a lot in “organic” skincare products. It is a good moisturizer that not only hydrates the skin but also strengthens the cell membrane. This helps to lower the water loss over time. It also softens the skin and reduces irritation and redness. It’s often used at a 3-5% concentration depending on the product.