Most lighter fluids are one of three types: charcoal, butane and Naphtha.
Butane is a byproduct of distilled natural gas and is odorless and colorless. Although highly flammable, it is completely safe to use as a lighter fluid and has a high heating value. It also has the advantages of being relatively inexpensive and does not give off the often unpleasant odor that other lighter fluids have. It is also known as Liquified Petroleum Gas, or LPG.
Refilling a butane lighter does take some skill and to fill it you should turn the lighter upside down and have the flame setting turned down as low as possible. You should then attach the far end of the fuelling can to the lighter’s adapter. Once the lighter is full, stand it up for a while to allow the gas to settle; once this has been done, you can alter the strength of the flame and use it.
Naphtha lighters have the advantage over butane of being reusable and although refilling a naphtha lighter also takes some practice, once you have done it the first time, it becomes easier. These lighters use a soaked cloth wick which helps to stop any leaks. The closed top also allows the volatile liquid to safely and easily evaporate.
This is often used to light charcoal in an outdoor grill and can be used with both lumps and briquettes; the briquettes often being sold already soaked with charcoal lighter fluid.
Charcoal lighter fluid is extremely flammable, toxic and also gives off a rather strong odor which can affect any food being cooked. This has caused some controversy over exactly how healthy this method of cooking actually is. Charcoal also contributes to smog and is not particularly good for the environment. The trend today is towards cleaner and healthier alternatives such as charcoal chimneys and electric charcoal starters.