TL;DR
A stain-blocking primer is an undercoat formulated to lock down discolorations such as water marks, smoke residue, tannin bleed from cedar and redwood, ink, and crayon so they cannot migrate through the finish paint. Shellac-based versions are the strongest sealers for smoke and water stains, oil-based handle tannins well, and modern waterborne acrylics cover lighter cases with easier cleanup.
What it means
A stain-blocking primer is an undercoat formulated to lock down discolorations such as water marks, smoke residue, tannin bleed from cedar and redwood, ink, and crayon so they cannot migrate through the finish paint. Shellac-based versions are the strongest sealers for smoke and water stains, oil-based handle tannins well, and modern waterborne acrylics cover lighter cases with easier cleanup. Painting over a stain without one is why the same brown ring reappears through two fresh topcoats.
Where it sits in the glossary
Stain-blocking primer 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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