The specific gravity of a product can be found on the material safety data sheet. how do you know if a product will sink in water?

Specific gravity is the ratio between the substance's density and the density of water. Being a ratio of dimensions with same units of measure, this value is unitless. 

The substance or objects sinks in water if its density is greater than that of water. On the other hand, it floats if its density is lesser compared to that of water. 

Having said so, the substance or object sinks in water if the specific gravity is greater than 1 and floats if the specific gravity is lesser than 1. 

              sinks:     SG > 1
              floats:     SG < 1