| MadSci Network: Chemistry |
Dear Caitlin, Nail polish in the bottle has three main ingredients: pigment [the colored stuff], binder [the glue that holds it onto your nail] and the vehicle [the solvent that makes it all a liquid]. The "sink or float" property is determined by density, how much a given volume weighs. Most pigments are denser than water and sink. Most binders have about the same density as water and will be suspended, most solvents [at least those used in nail polish] are less dense and will float on water. The density of the liquid polish is simply the fraction-weighted average of all three major ingredients. Since liquid polish floats on water, the density must be less than that of water. Once the polish is floating, it is easy for the solvent to evaporate to the air [this is the odor you smell when doing your nails]. The colored glob left behind is really no different that the color on your nail. If it doesn't sink either, then it's density is also lower than water [only now the density is computed from only the pigment and the binder.] What lead you to think that nail polish was denser than water in the first place? When an experiment disagrees with a supposition, it is very often because the supposition was false. This is the very essence of the scientific method. Thank you for your question to MadSci Network! If I can help any more, please send me an e-mail. Regards Ken
Try the links in the MadSci Library for more information on Chemistry.