Retarder in zinc oxide eugenol is

Setting Time and Factors Affecting ZOE: The normal reactivity between zinc oxide and eugenol is very limited and must be accelerated in order for the material to have a practical clinical application. Acceleration of the set may be achieved by: Incorporating chemical accelerators in the mix (the most efficient and predictable way of controlling the setting time). Reducing the powder particle size, providing for accelerated reactivity. Increasing the powder: Liquid ratio (of limited effect in reducing the setting time). Increasing the percentage of rosin and fillers. Increasing the temperature and/or humidity. Adding water to the original mix or after mixing is complete and seated into the preparation. Introducing greater energy in the mixing procedure (pressure-movement and time). A delay in setting is rarely needed. This is accomplished by adding vegetable oils or glycerin which keep the mass plasticized for a long period of time. Ref: Marzouk’s operative dentistry page no 263