On the topic of Solder. I have a question for all of the learned fraternity. About 20 years ago i bought a 500g reel of flux cored solder. Can anyone tell me the shelf life I should have expected please? When I went to use it on Thursday, when making a joint (silicon wire/solder tag on a motor) there was a black gungy residue left and no solder = no joint

Changed the solder for a 25g new packet

Result

The joint was sound. Unfortunately me being an Aberdonian I do not want to just throw out this old ree. So if anyone can give mae a little advice I would really appreciate it.
thanks
Jim
