Infusion is a very simple chemical process used with botanicals that are volatile and dissolve readily, or release their active ingredients easily in water, oil, or alcohol. The botanicals are typically dried herbs, flowers or berries. The liquid is typically boiled (or brought to another appropriate temperature) and then poured over the herb, which is then allowed to steep in the liquid for a period of time. The liquid may then be strained or the herbs otherwise removed from the liquid, creating an infusion. Unless the infusion is to be consumed immediately, it may then be bottled and refrigerated for future use.
The amount of time the herbs are left in the liquid depends on the purpose for which the infusion is being prepared. Infusion times can range anywhere from seconds (some kinds of Chinese tea) to hours, days, or months (liqueurs like Sloe Gin).
There have been several accessories and techniques for removing the steeped or left over products that were used to infuse liquids such as water, oil, or alcohol. The use of a metal steeper, which looks like a metal clamp. Tea infusers work as strainers and assist in removal of used herbs, leaves, etc., from over steeping or leaving residues. French presses are commonly used to infuse water with various teas and coffee. Lastly, and most commonly used, the tea bag. Tea bags today are made with filter paper and filled with various tea flavors.