Makeup is subject to the same liquid and gel laws as all other substances, so if you're taking liquid mascara, lip gels (such as Blistex ointment), or other liquid-or gel-like things, they must be packed in 3.4-ounce or smaller containers in your quart-size plastic bag. Anything larger than that requires special packaging. Mascara is made from natural or synthetic fibers which are mixed with a thin layer of glue called titanium dioxide. This forms tiny particles that stick to the lashes giving them length and volume. While most people think of mascara as a liquid, it actually dries into a powdery substance that is easy to wash off skin. However, since it remains on the surface of the lash it can be felt through clothing. The type of fiber used in mascara affects how it feels when you apply it and how long it lasts. Natural fibers such as silk produce a more flexible product that doesn't crack or split while synthetic fibers such as polyamide provide more durability. Also, some types of mascara dry down to a powdery residue that's visible on skin if you breathe deeply. These types of products can cause asthma attacks in people who are already vulnerable due to their condition. Mascara that contains zinc oxide or waxes that melt at body temperature are not likely to cause problems since they don't dry down.