Lubricant or Moisturizer

Graphite is a lubricant, because the fine grains of carbon slide on each other without adhering. Oils are chains of carbon and hydrogen units joined end to end that are liquid (and incompressible) at room temperature. Because they flow, like water, they are called hydrocarbons. Oils are slippery, because hydrocarbon chains slide over and around each other without chemical interaction. Common oils do not dry out, because their chain lengths are too long to favor evaporation. Non-reactive Vegetable and mineral oils can be used on skin safely.

A gel is a molecular mesh that happens when very long molecular chains, dissolved in water, fold on themselves and stick at contact points. A gel is a molecular matrix in a drop of water. Just like an oil, lubricity and elasticity result from chains sliding over and around each other. Cellulose and starch are natural chains of sugar molecules. Cellulose forms loosely gliding nano-fibers in water, making it a fine lubricant and the basis of water soluble personal lubricants for the last 80 years. Other long chain molecules can be used for personal lubricants, but most that are non reactive that have been tried are stickly, tacky, string out, or are not biodegradable, which makes them less suitable for repeated intimate use..

Water makes up 80 to 95% of commercial personal lubricant gels. They evaporate, which limits the time of use. Humectants like glycerin and propylene glycol are added to retard evaporation. (This is also the way that coconut shreds are kept moist in the bag). Bacteria, spores, and molds live in water environments and thrive in solutions of sugar molecules. For this reason, all water based products must contain broad spectrum antimicrobials, i.e. "preservatives". These compounds can provoke allergic reactions or alter the natural bacterial populations of genital skin.

There is a lot of water in the cells of the body - trapped in gels. Because healthy tissues are 'juicy" and old and atrophic tissues are dry, fragile and easily injured on the outside, there has been a lot of cosmetic attention to "moisturizing" skin. SKIN IS WATERPROOF. Putting water on the outside doesn't moisturize skin at all. Vaginal moisturizers are thin gels that retain water. Applying them retards moisture loss from genital skin, which is a supportive measure, not necessarily therapeutic. There is no real distinction between water based vaginal moisturizers and lubricants except for the viscosity or degree of lubricity of individual preparations.