If I buy 5 gal of Liquid soft bait material, how long will it stay usuable? i would like to experiment now that I have fish to work on and wait until winter to go into production.

Indefinately, however the resin will settle to the bottom and you will need to stir it well before each use. The big 2 foot long paint drill stiring attachements work well. If your experimenting, you might want to start with gallons, easy to shake before using and you can order different hardness to play around. Once you buy 5 gallons, if you don't like the consistancy, you've got a lot of plastic on your hands.