Gel fuel is a mixture of denatured alcohol, water and gel. Several commercial products are available, and they are relatively inexpensive. The cans are easy to open and light quickly, emitting a low-heat flame that generally lasts about two hours. Caterers like them because they keep food hot even during a lengthy dinner service, and they don't require a lot of fuss. The canisters are available in food warehouse and hardware stores or can be special-ordered from your local supermarket.
Fill the bottom pan of the chafing dish with very hot water. Chafing pans are designed to act almost like double boilers. A bottom pan is filled with two or three inches of water, which conducts heat to your food. The food pan fits inside the water pan and is covered until it is time to serve. Gel fuel will keep the water heated so your food stays hot.
Remove the cap to the gel fuel can with a small knife or the edge of a spoon. Put the cap aside in case you want to reuse the fuel at a later date.
Place the gel fuel into the cavity of the chafing pan. Most chafing pans are designed with a space into which these cans fit.
Light the fuel carefully by touching a match or lighter near the exposed gel. Although gel fuel emits a relatively low heat, be cautious of the open flame. Never allow children to light the gel fuel containers.
Keep an eye on the fuel to make sure it stays lit and maintains an even heat. If the chafing pan is set up outdoors, wind can occasionally extinguish the flame. If the service lasts a long time, you may need to replace the fuel canister.
Pop the lid back on or blow out the flame when the service is over. Discard empty fuel cans in the garbage.