I have used epoxy that was sitting on a shelf for several years and there have been no problems. (mas)

: 6 months is not that long. If the epoxy is somewhat cloudy, put the bottles
: in warm water for a while and then give them a good shake to mix up the
: chemicals. If the pumps are not working or are a little stiff, soak a rag
: in acetone and wrap the cloth around the tops of the pumps. Then cover the
: whole rag in a small zip lock bag or plastic and seal tightly with a twist
: tie or elastic band. Leave the rag on for a while and let the fumes do
: their work.