Soldering is a low-temperature process by which two or more items (typically metal) are joined together by melting a filler metal (solder) into the joint. An electrically powered soldering iron or soldering gun is used to melt the solder which is an alloy of lead and tin that has a melting point below the melting point of the items being joined. A chemical cleaning agent called flux is also used to clean the surfaces before soldering.
A chemical cleaning agent called __________ is used to clean surfaces before soldering.