The typical average specific gravity for the resin is 1.10 g/cc and for the hardener is 1.00 g/cc. When the products are originally formulated it is by weight and not volume. Therefore 2 cc of resin has a weight of 2.2 grams and the 1 cc of hardener is 1 gram. As you can see by weight that leaves a shortage of 0.1 grams of hardener when done by volume.