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Name: Kendra H.
Status: educator
Age: 30s
Location: N/A
Country: N/A
Date: 5/19/2004


Question:
How is it that nail polish can literally melt the bottom of a plastic Dixie-style cup but not damage the nail surface in similar ways?


Replies:
Kendra,

It is because the nail and cup are made of very different materials. For dissolving to occur, there must be some sort of "compatibility" between the solute (that dissolved) and the solvent (that which does the dissolving). Nails are made of a protein (keratin) that is very different from the Polystyrene foam or other plastic in the cup. That is why the nail polish remover can remove (plastic) nail polish and not dissolve the nail. Water will not dissolve the cup, but it will soften the nail. Again, it is a matter of compatibility.

Regards,
ProfHoff 851


Polystyrene foam cups and nails are not the same material. Polystyrene foam is "foamed" styrene -- which is soluble in the solvents used in nail polish remover. Your fingernails are made of a protein-like material -- more similar to Nylon.

Your nail-material is insoluble in nail polish remover. Different substances are more or less soluble in different solvents. For example, salt dissolves in water but not in alcohol. Like substances tend to dissolve in similar substances. Un-like substances tend not to dissolve in un-like solvents.

Vince Calder


Dried nail polish is made of simple plastics similar to the disposable plastic drinking cups. So the liquids used to dissolve the nail-polish plastic (so they can put it in a bottle for you to paint onto fingernails) are the same liquids that can dissolve disposable cups , or glue them together if you're careful to use just a little and dry it soon.

Fingernails, on the other hand, are made of protein, like wool, not of plastics, like polyester. Because they are built of molecule fragments from a different family, proteins do not dissolve in the same liquids, and some cannot truly dissolve in any liquid. For dissolving proteins, very strong alkalinity, some water, very heavy solvents, and boiling temperatures help. Alkalinity and water are irrelevant to most plastics. I think there are a few "heavy solvents", perhaps n-methyl-pyrolidone or DMSO, which more or less dissolve both fingernails and plastics.

Jim Swenson



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