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.
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.
Pentylene Glycol is a great replacement for Propylene Glycol. It has very similar characteristics but it’s derived from plants (usually from corn). Natural cosmetics lovers will find this component very useful. It enhances the moisturizing effect of cosmetic products, improves the efficiency of preservatives and it’s an effective emulsifier. It’s approved by ECOCERT and COSMOS so it’s considered to be 100% safe and can be used in vegan products.