The solder works nicely, I searched to find the maker on the web,
and I ended up on one Chinese factory, that haves a major European presentation.
MBO (Métaux Blancs Ouvrés) has been a reputable French supplier of solder since my younger ages..
How did you discover that the factory is in China?
I'm using since many years Dave's recommended solder (60-40 Ersin Multicore) but in larger diameters (0.7 mm for standard PCB and 1.0 mm for larger wire to connector soldering).
After seeing the Solder Tutorial Video I searched for a 0.5 mm roll that was sitting in a closet and tried it.
After about 1000 joints I returned to the larger diameter, because I discovered that it allowed for a faster work: shorter time for a good joint.
When I hand solder IDC connectors to a PCB, I use a very large, very hot tip and 1.0 mm solder: I move quickly the tip and the solder wire in the middle of the two rows of pins and I'm done, in 10 seconds for a 26 pin connector.
Soldering wire is really a personal taste....
Regarding shelf life, time ago I tested some very old solder (more than 30 years old) that I bough for practically nothing, and discovered that some rolls were still very good (the flux had a "smell" different from the new ones, but they gave good, clean joints) but others were practically unusable : the flux had hardened to the point of not liquefying, and the smell was terrible.
I think that shelf life has to do with flux life, and maybe it can be increased by keeping the solder in an air-tight container.
Regards