You can clean gear with a brush and water alone, but better cleaning is possible through chemistry. Don't reach for the squeeze bottle of dish soap! Regular soaps leave a sticky, rinse-resistant residue.
Commonly Available Cleaners
Automatic dishwashing detergent — In a pinch, the detergent used in your dishwasher can be used. Add 1 tablespoon per gallon of water. Exceeding this may etch glass. A thorough rinse is required to remove any surfactants. Rinse with hot water until the surface no longer feels slick.
Bleach — Regular unscented bleach is a brewing mainstay. It's cheap, widely available, and effective. Throw a couple of tablespoons in a full bucket or carboy and let it sit for hours. Don't let metal sit in prolonged contact with bleach water, to avoid corrosion. Completely rinse and air-dry before use.
TSP (Trisodium Phosphate) — Cheaper than dishwashing detergent and available at hardware stores, hot water and TSP speedily eats brewery funk. Make sure the TSP you buy is food grade.
Sodium percarbonate cleaners — Sodium percarbonate cleaners, like Oxiclean, release hydrogen peroxide (H2O2) when mixed with water. The peroxide attacks stains quickly. Buy “crystal-” and fragrance-free versions and rinse well.
One-Step — A cleaner that combines sodium percarbonate with alkaline agents. The One-Step manufacturer claims no rinsing is needed and that prolonged contact time sanitizes your gear. However, One-Step is not an FDA-certified sanitizer.
PBW (Powder Brewery Wash) — PBW from Five Star Chemicals is the strongest of the percarbonate cleaners. PBW solutions dissolve almost any brewery mess. It has an added advantage of rinsing easily. Mitigate the cost by buying in bulk.
With all chemical solutions, follow basic safety by adding chemicals to water, not the other way around. Adding water to chemicals can superheat the mixture to explode or cause splashes of ultraconcentrated solution.
Caustic (i.e., sodium hydroxide or lye) is the cleaner of choice in professional breweries. Due to the danger, home use is highly discouraged. Caustic solutions chemically burn on contact. This stuff is what's used to unclog drains and clean greasy ovens!
Common threads in the cleaner discussion: hot water and rinsing. Hot water speeds the cleaning reaction. Careful rinsing ensures a clean surface. Let the gear soak just as long as needed, otherwise etching may occur. With powdered detergents, a hard white film can form (a quick soak in a vinegar solution can loosen it).
If you're tempted to use your dishwasher for cleaning, don't! Between drying and clean rinse agents (like Jet Dry) and inconsistent application of cleaner and rinse water, there are too many variables to depend upon the machine to achieve “beer clean.”