Is the material left in my 400 ml cartridge still 'good' after I have opened and used the cartridge?
The unmixed components (Parts A & B) remaining in the cartridges is still good, usable material. If the static mixer was left on the cartridge and the material in the mixer was allowed to cure, then that will act as a seal to extend the life of the unmixed material.
To use you must remove the 'used' static mixer, clean off the manifold on the cartridge where the material comes out with a clean paper towel. Screw on a new, unused static mixer. You can now dispense the remaining material in the cartridge.
NOTE: Approximately 26 grams of material will remain in the static mixer.