Our filler metals have to be stored at temperatures well above the dew point any time. This can be maintained safely in a heated room at a temperature above 15° Celsius and a relative humidity below 50%.
Storage at very high temperature (> 25° Celsius) shall be avoided as well, due to the fact that the lubricant on the wire may volatilize too early.
When material is taken from the storage always choose the product with the oldest manufacturing date (FIFO)!
Filler metals that are not fully consumed have to be packed prior to storage.
Obviously damaged or wet packages of filler metals can be used only after approval from a qualified person (manufacturer, welding supervisor). Drying of wet welding wires or rods is not possible.
A maximum duration of storage cannot be specified in general. In doubt a qualification by welding tests must be performed.