Flux

Metallurgy

In metallurgy, a flux (derived from Latin fluxus meaning “flow”), is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time. They are used in both extractive metallurgy and metal joining. -- Courtesy of Wikipedia.

Why

This is the stuff which no reprap(ed)household/solderer should be without. Even your solder contains it.

• It's cheap.
• Readily available.
• It's there for you, your reprap and your electronics in dire need.
• It's toxic.

Get two packages when you think of getting one.

Did I say its essential?