the answer is mucus
The protective coating that forms on sheet lead is called lead oxide.
The metal that forms a self-protective coating when exposed to air and moisture is iron. This self-protective coating is known as iron oxide, or rust, which acts as a barrier to prevent further oxidation of the metal.
Cotton is the protective coating around cotton seeds. It forms as the cotton plant grows into a mature shrub.
a solid substance (s), a group 3 element, that forms a positive ion. it reacts with air, although this is not commonly known as it quickly forms a protective coating of aluminum oxide.
Nickel
The white matter in the brain is created by myelin, which is a fatty substance that forms a protective coating around nerve fibers. Myelin helps to insulate and speed up the transmission of electrical signals between neurons.
Before they moult it, the protective coating of arthropods is referred to as the exoskeleton. The pieces of moulted exoskeleton after removal are called exuviae.
Chrome
the protective protein coating
Fluoride protects your teeth by putting a protective coating on your teeth. The protective coating helps prevent bacteria from damaging your teeth.
water repellent forms a smooth coating over the tiny holes in fabric. the coating is so smooth that the gaps in it are smaller than water molecules. because the water molecules cannot pass through the protective coating, they stay on the surface where they can be easily wiped away.
Extra heavy soil pipe (CI) requires NO Coating