If you use a gas stove, you may notice that the flame from the burner sometimes leaves unsightly black marks on your pots. There are a number of possible reasons for this; some are easily correctable, while others might be indicative of a greater problem.
Scorching on pots may simply indicate that the burner's flame is too hot. If the flame can be seen licking up the sides of the pot, it should be turned down. This may also indicate that the burner is too large for the pot. An uneven grate may also put one side of the pot closer to the flame than the other. This problem can be quickly solved by controlling the flame or repositioning the grate.
Blackening on pots may also indicate that one of the stove's hobs is depositing soot. This is more than merely annoying; soot deposition means that the stove is not burning properly, possibly generating an unsafe level of carbon monoxide. Carbon monoxide poisoning can act quickly in an unventilated area, with possible risks ranging from headaches and dizziness to vomiting and even death.
Recognising incomplete combustion
The colour of a gas stove's flame is a good indicator of whether or not incomplete combustion is occurring. A healthy flame will be blue. If the tip or body of the flame is yellow, the stove needs to be serviced; it may not be getting enough air to burn properly. Using the stove while it is still burning with a yellow flame could be highly dangerous.
Cleaning blackened pots
Black marks on the outside of pots can be difficult to clean, but a little persistence will soon remove the worst of the damage. Scrubbing the exterior of the pot with a scouring pad while running warm water over it will remove much of the soot. For tougher areas, apply a mixture of water and vinegar or a commercially-available cleaning compound.