Can I paint over alkyd with latex?

Yes, you can paint over alkyd with latex, but proper preparation is essential because latex is water-based and alkyd is oil-based, and adhesion can fail if you paint directly over glossy alkyd without prep. Alkyd paint cures to a hard, glossy, slick finish that latex does not easily grip. To paint latex over alkyd, first clean the surface thoroughly with soap and water or TSP to remove grease, dirt, and grime that prevent adhesion. Then lightly sand the alkyd surface with 150 to 220 grit sandpaper to degloss and create a mechanical key, dull the gloss so latex can grip. Wipe off all sanding dust with tack cloth. Next, apply a high-quality bonding primer, such as oil-based primer or water-based bonding primer like Zinsser Bulls Eye 1-2-3 or Benjamin Moore Fresh Start, which adheres to oil and allows latex to adhere. This primer step is critical to prevent peeling. After primer dries, you can apply latex paint in two coats. If existing alkyd is in poor condition, peeling, or chalky, scrape loose paint and prime bare spots. So yes, you can paint latex over alkyd with cleaning, sanding, and bonding primer.