Lead free solder paste
MG Chemicals has developed a unique flux system designed specifically for high temperature lead free alloys. It provides the fluxing activity levels that promote thermal stability and prevents thermal degradation when reflowing under air atmosphere (normal). Since use of nitrogen is not required, MG 4900P Lead Free Solder paste will provide excellent cost savings.

In addition, MG 4900P Lead Free solder paste exhibits superior joint strength, excellent wettability, and extraordinary print definition and tack life. The post soldering residues of MG 4900P are non-conductive, non-corrosive and highly insulated.

Shelf Life (see technical tab for more information) :
Unopened container (30-50°F/2-10°C) – 6 Months
Unopened container (68-77°F/20-25°C) – 1 Months
Opened container (68-77°F/20-25°C) – 24 Hours

Features:
Low residues
Easily dispensed
Long tack-time
Excellent wettability
Hard non-conductive residues

Manufacturer datasheet - 4900P-25G (Adobe Reader required to read datasheet)

Reusing Solder Paste (as per manufacturer):
This is not normally recommended, because it typically generates more problems than it is worth. If you do decide to reuse solder paste, these pointers may be helpful. This paste should be tightly sealed and refrigerated. Then, the paste may be reused at a later date, provided that the paste has not separated or thickened significantly compared to its original properties. Storage of syringes is preferred in an upright position with tip down to prevent flux separation and air entrapment.