This is something that has been trial and error over the last 10 years. I discovered accidentally that colloidal silver provided broad spectrum anti- bacterial and anti-fungal protection. Colloidal silver is a wonderful skin healer - which is why I had used it and continue to use it. However, I also believe that if a product is going to be a natural emulsion (containing water and oils) it shouldn’t be able to be stored for long periods of time - I wanted the products to retain the integrity of the bio-activity of each ingredient. Any of my products that have waters in it - have a short shelf life; to be used within 6 months of opening. I am also a strong advocate and user of beauty balms. They don’t need a preservative as they are anhydrous (without water).