Let’s say I buy an X amount of paint, which has a total mass of 5kg (or 5lb). I spread the whole content on my wall and 24hrs later the stuff has “dried” and my wall has taken on a new shade.
So chemically what has actually happened to that liquid that weighed 5kg/lb? Did it change phase to a solid, adhered to my wall, and then added 5kg/lb to the weight of the wall?
In: Chemistry
Paint typically has a level of solvent in it that evaporates away. So your wall doesn’t gain 5 kg of mass it gains 4 and the other kg goes out into the world as a vapor. The solvent dissolves the solid pigments so it’s liquid, but once the solvent is gone the solid pigments stay.
If you ever opened an old can of paint and see the top layer of the can is really watery and the bottom is thick and gooey. That’s why you have to shake and stir it.
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