Do I need to prime before using alkyd paint?

Whether you need to prime before using alkyd paint depends on surface condition. For bare, untreated surfaces like new drywall, bare wood, bare metal, and masonry, you need to prime before alkyd paint to seal surface, provide adhesion, block stains and tannins, and ensure uniform finish. For bare wood with tannins like cedar and redwood, oil-based primer is essential to block bleed. For bare metal, rust-inhibitive primer prevents rust. For previously painted surfaces in good condition, well adhered, clean, and dull, you may not need to prime before alkyd, just clean and lightly sand to degloss, then apply alkyd topcoat, as alkyd adheres well to existing paint. However, if existing paint is glossy, stained, peeling, or you are changing from dark to light color drastically, priming with bonding or stain-blocking primer improves adhesion and coverage. For spot repairs with bare spots, prime those spots. So you need to prime before alkyd for bare wood, metal, drywall, and stained or glossy surfaces, but not necessarily for previously painted surfaces in good condition that are cleaned and sanded. Priming ensures better durability and true color.