Final answer:
Rubbing alcohol is not a sealing agent. Sealing agents like collodion, rubber cement, and clear nail polish create a protective layer, while rubbing alcohol is used for cleaning and antiseptic purposes and evaporates without sealing.
Step-by-step explanation:
Among the options provided, rubbing alcohol is the substance that is NOT a sealing agent. Sealing agents are materials that are used to prevent the passage of liquids or gases. Collodion is a flammable, syrupy solution of pyroxylin in ether and alcohol which, when applied to the skin, dries to form a flexible and waterproof film. Rubber cement is an adhesive made from elastic polymers typically mixed in a solvent that also forms a strong bond when it dries. Clear nail polish is a lacquer applied to nails that dries to form a hard and protective layer, effectively sealing cracks or ends of nails. On the other hand, rubbing alcohol, which is generally isopropanol or ethanol, is used primarily as an antiseptic or cleaning agent and evaporates quickly without forming a protective layer.