The shelf life of any ingredient is always counted from the date the ingredient is produced by the manufacturer. At the time a customer receives the product it may already have lost some of its shelf life. However, the shelf life provided by the manufacturer is always only an estimate and often intentionally kept short. Once the expiration date is reached, the manufacturer re-tests the particular batch upon request and issues a new shelf life which is usually as long as the first one. For that reason, the cosmetic industry uses the term re-test date rather than expiration date.