LIQUID GRAVITY Deluxe Materials Liquid Gravity is an ingenious product for adding ballast to models. Liquid Gravity can be used for adding nose-weight to a model aircraft very accurately, as it is made up of tiny, non-toxic, easy-flowing dry beads that can be pored into a cavity and then "fixed" with a cyano glue. Each pack weighs 240g so there is more than enough for the heftiest free-flight glider or rubber-powered model.