Colloid Chemistry 101

QUESTION:

Just a comment on your answer to the question on applying Teflon coatings. I am fairly confident that there are no liquid Teflon coatings that are emulsions. They are all dispersions of the Teflon powder in a liquid medium (water or solvent based). Emulsions are mixtures of two non-miscible liquids—one being emulsified in the other. Teflon does not exist as a liquid at room temperature. Also, Teflon is a registered trademark of the DuPont Co., and DuPont is the sole manufacturer/supplier of it. I enjoy reading your column. J.L.

ANSWER:

You are absolutely right, J.L., and thanks for pointing it out. Furthermore, you are being too kind. You and I both know that you are absolutely confident that there are no liquid Teflon coatings that are emulsions. I knew that. Why did he think I didn't know that? As with a slip of the tongue, a slip of the pen is not the fault of the mind. After all, I am not as dumb as I look—and that's a blessing!

For the record, the following definitions are shown in the Federation of Societies for Coating Technology "Coatings Encyclopedic Dictionary":

Emulsion—two phase liquid system in which small droplets of one liquid (the internal phase) are immiscible in, and are dispersed uniformly throughout, a second continuous liquid phase (the external phase)

Dispersion—(1) any composition, process, or state, relating to heterogeneous systems of solids, gases, liquids or immiscible liquids . . . (2) process of dispersing a dry powder (or pigment) in a liquid medium in such a way that the individual particles of the powder become separated from one another . . . throughout the entire liquid medium.