All of our products are packaged and sold by weight, not by volume. Since many products have a unique density, the volume of 1 pound of one material may not be the same as the volume of 1 pound of another.
Additionally, there are a limited number of standard size containers available, so we choose the standard container size that is closest to the volume we need for a given product.
And finally, the mix ratio of some products will determine how much A or B goes into the standard size container to complete a kit.
For example. Our Poly 15-3 Liquid Plastic has a volume of 18 cubic inches per pound. Our Poly 1512 Liquid Plastic has a volume of 25.1 cubic inches per pound. When we package this material in 5-gallon pails, we can fit 40 pounds of part A in one pail, and 40 pounds of part B in another, making it an 80-pound kit. However, the Poly 15-3 is denser. For this product we can fit 50 pounds of part A and 50 pounds of part B into each pail, making this a 100-pound kit. Even at 50 pounds, the pails are not quite full, but we didn’t want them to be too heavy to handle, so we stopped at 50.
For some silicones, the difference in density between A and B, combined with the mix ratio of 1A:10B, means we package A and B in different size containers. Each container may not be completely full since we need to balance the full kit ratio by weight, not volume.