What kind of primer to use with alkyd paint?

What kind of primer to use with alkyd paint depends on surface, but generally oil-based or alkyd primer is best for compatibility and sealing, though high-quality bonding primers also work. For bare wood, especially woods with tannins like cedar, redwood, and for knots that bleed, use oil-based or alkyd primer like Zinsser Cover Stain or KILZ Original oil-based to block tannins and provide good adhesion for alkyd topcoat. For bare metal prone to rust, use oil-based rust-inhibitive primer like Rust-Oleum rusty metal primer. For drywall and previously painted surfaces in good condition, you can use oil-based primer or water-based bonding primer, but oil-based primer provides better sealing and adhesion for alkyd topcoat. If you are painting alkyd over latex, you can use bonding primer to ensure adhesion. For exterior wood, oil-based exterior primer is best. So best primer for alkyd paint is oil-based or alkyd primer that matches topcoat chemistry, such as oil-based wood primer for wood, rust primer for metal, and stain-blocking oil primer for tannin-rich wood, providing sealing, adhesion, and blocking. Avoid using plain latex primer under alkyd for bare wood with tannins as it may not block.