Surface Preparation第 18 / 100 题
Knots and sap streaks in bare softwood can bleed through paint unless they are sealed with what?
a.A thin coat of water
b.Only the finish paint
c.A stain-blocking primer (such as shellac-based or a dedicated knot sealer)
d.A coat of clear caulk
解析
Resin and tannins in knots and sap can bleed through ordinary paint, leaving yellow-brown stains. A stain-blocking primer, often shellac- or oil-based, seals the knot so it does not discolor the finish. Spot-priming the knots before the full prime coat is common practice.
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