Finish TradesQuestion 434 of 700

Before finish painting new interior woodwork that contains knots in the wood, why is a stain-blocking primer recommended over the knots?

a.Knots can bleed resin and tannins that discolor the finish coat unless sealed
b.Knots make the wood too smooth for paint
c.Knots repel all water-based products
d.A stain-blocking primer adds structural strength to the trim

Explanation

Knots can release resin and tannins that bleed through and stain the topcoat, so a stain-blocking primer seals them for a clean finish. Knots do not make wood too smooth or repel all water-based coatings, and primer provides no structural strength; its role is sealing and adhesion.

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