Glycerine tinctures
Glycerine has anti-fermentative properties that are efficient for preservation.A glycerite has a shelf life of 14-24 months,versus an alcohol extract with a shelf life of 4-6 years.
When making a glycerite with dried herbs,it is common to use water to rehydrate the herbs and loosen up the botanical matter.Generally a mixture with 60% or more glycerin to 40% or less water is a safe ratio.To err on the side of safety I go with a 75% glycerine to 25% water ratio.If you are working with fresh moist herb,you can go with 100% glycerine for your extract just be sure to muddle well.