How long will the briquets stay hot?

If you’ll be cooking for more than 40 minutes, additional briquets must be added to the fire. However, never add Kingsford┬« Match Light┬« briquets to an existing fire; add regular Kingsford┬« briquets in the following manner: Add 10 or 12 briquets to the outer edge of the fire immediately after it has been spread. Once these coals become 70% ashed over, add to the center of the fire as needed to maintain constant cooking temperature.