TL;DR
Plumbing flux is the acidic paste applied to cleaned copper pipe and fittings before soldering; it strips remaining oxides so molten solder can wet the metal and wick into the joint. Potable water lines require water-soluble formulas meeting ASTM B813, because petroleum-based pastes leave residue that corrodes pipe and fouls drinking water.
What it means
Plumbing flux is the acidic paste applied to cleaned copper pipe and fittings before soldering; it strips remaining oxides so molten solder can wet the metal and wick into the joint. Potable water lines require water-soluble formulas meeting ASTM B813, because petroleum-based pastes leave residue that corrodes pipe and fouls drinking water. Excess left inside a joint is a classic cause of pinhole leaks that surface months after the work.
Where it sits in the glossary
Plumbing flux is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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