When I teach cleaning science, I try to decompose that amalgam into components so I can reduce the complexity. I have developed four “laws” which let me communicate the basics of cleaning without using chemical structures or mathematical formulas. Two will be covered this month, and two in the next C4 column.

KESEY’S LAW OF CLEANING
The most important law is often attributed (falsely I believe) to the novelist Ken Kesey, author of One Flew Over the Cuckoo’s Nest. It is also attributed to someone named Imbesi (and called their “Law of Fifth”). And it’s simple:

Whenever something becomes clean, something else becomes dirty.

We don’t clean the particles from semiconductor surfaces. We don’t clean the pyrogens from medical implants. We just move (hopefully) the particles and the pyrogens from where they are to where we want them to be. The particles are suspended in a moving stream of fluid, which can infect another surface. The pyrogens are bound by intermolecular force to a detergent soluble in water, which can also infect another surface.

It’s the aqueous detergent or organic solvent which gets dirty–when our parts become clean(er).

Success in cleaning is really two things: first moving the soil from the base surface, and second, moving it from the place we put it (the cleaning agent) to the place we want it (usually some recovery process).