Tannin bleed: specify a wood-trim repaint

Find out what is beneath the white finish

In an office reception or retail interior, a brown streak on white trim can look like an incomplete colour change. Start by identifying the component: solid wood, veneered millwork or another material. Record knots, joints and the locations where discolouration appears. Keep the actual material unknown if no reliable record exists; a woodgrain appearance is not sufficient identification.

Ask when the marks first appeared relative to installation or repainting. Include previous primer and finish records if available. Do not bundle wood trim with the adjoining drywall simply because both will be white. Separate the trim lengths, faces and returns so the contractor can allow for a different preparation and primer decision.

Make tannin blocking a stated requirement

Sherwin-Williams describes tannin staining as wood extractives migrating through the coating and notes that some woods and knots are prone to it. Its guidance calls for an appropriate stain-trapping coating and warns that bleeding can still occur despite recommended preparation and products. More ordinary topcoat is therefore not a complete specification for this particular defect.

Request the proposed primer and finish by exact product, with confirmation that the system suits the identified wood and commercial location. Ask how the contractor will assess existing adhesion and distinguish newly exposed timber from previously painted areas. If moisture is implicated, arrange the necessary building review separately. This is a purchasing checklist, not instructions for stripping unknown coatings or selecting solvents.

Reference: Sherwin-Williams: tannin staining

Approve a trim-specific trial and fallback

Choose a trial that includes the troublesome knot or streak, not just an easy clear section. Have the contractor record the preparation, primer, finish and review timing. Colour approval and stain-blocking assessment are separate decisions: a pleasing white sample does not establish that the proposed treatment addresses the marked area.

Agree what happens if staining appears during review. The next step might be a revised treatment proposal for that component, rather than another unplanned coat across every wall. Identify who approves an expanded trim scope and whether adjoining surfaces need protection again. Retain the trial record with the millwork schedule so a future repaint does not repeat a system already found unsuitable.

Does choosing a darker finish solve tannin bleed?

A colour change is not evidence that the source of staining has been addressed. Ask for the wood-specific assessment and treatment rationale before accepting a cosmetic change as the solution.

Put the planning into practice

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Discuss your commercial project

For offices, retail spaces and other commercial interiors, review the surfaces, access and protection questions covered by our commercial interior painting in Saskatoon service.

Have a location and a rough scope? Request a commercial painting quote with the details you have. Access, timing and project requirements can then be reviewed for your property.