Citric Acid is a natural perservative - dissolve in into your liquid Tea Tree EO is also a natural perservative and also a natural anti bacterial agent with healing properties. You may have to scent your lotion a little heavier to cover the smell of tea tree but it can be done. Vit E as mentioned is a natural antioxident grapefruit seed extract( a by product of the citrus industry, it is all vegetable antioxidant) is also another one - It also contains Vit c and has been known to be Antibacterial and antioxidant among other properties. As with any all natural product products - shelf life is limited - a proper bottle for dispensing is also very important as to not to introduce bacteria into lotion. HTH