Solder includes silver solder consisting of solder core and coating. One of the functions of silver solder core is to conduct electricity as electrode, and it is also the main material to form weld metal. Therefore, the quality of solder core directly affects the performance of weld. The solder core of high quality steel fired carbon steel is usually 0.08% C low carbon steel. The most widely used are H08 and H08A, whose carbon content is 0.08% C. As well as the harmful impurities of sulfur and phosphorus, the diameter of common solder (i.e. the diameter of solder core) is 2.5-6 mm and the length is 350-450 mm. Although silver solder has the ability of resisting external damage in general, it can not be ignored that it is easy to be damaged because of poor storage. Solder is a ceramics product. It can't withstand impact as steel core, so it can't fall when loading and unloading. The solder packed in cartons cannot be carried by hooks. Some types of solders, such as alkaline solder coatings for special drying requirements, should be handled more carefully than normal solders. In general, the solder is packed in plastic bags and cartons. In order to prevent moisture absorption, the silver solder should not be disassembled at will before use. It should be disassembled as far as possible. If possible, the remaining solder should be sealed after welding. Acidic solders are not sensitive to water, while organic rutile solders allow higher water content. Therefore, according to the specific situation of damp, drying at 70-150 degrees for an hour, short storage time and good packaging, generally before use can not be dried. Alkaline low hydrogen solder must be dried before use in order to reduce the hydrogen content of solder and prevent defects such as pore and crack. Generally, the drying temperature is 350 C for one hour. The solder should not be put into the high temperature furnace or cooled abruptly in order to avoid skin cracking. If there is special requirement for hydrogen content, the drying temperature should be raised to 400-500 degrees C for one to one hour. The dried alkaline solder is best stored in another low temperature oven controlled at 50-100 C and is ready to use. When drying solder, each layer of solder should not be stacked too thick (generally 1-3 layers) to avoid uneven heating and moisture during drying. When operating in the open air, silver solder must be properly stored overnight. It is not allowed to be stored in the open air. It should be stored in a cryogenic box at constant temperature. Otherwise, it must be re-dried before use the next day.