PROTECTING METAL

The old saw about what makes for a lasting paint job goes double or triple for metalwork—whether cast-iron railings, fences, or interior window-sash fittings. Prepping the metal before priming adds years to the life of the finish coat.

OSPHO

When applied, this rust converter and primer stabilizes metal surfaces before painting. Applying or dipping rusty metal into a bath of Ospho (ospho.com) causes iron oxide (rust, in other words) to chemically change into iron phosphate, a dark, inert, hard surface that is paint ready.

LINSEED OIL

If the metalwork is small and can be removed from its setting (old doorknobs or castiron sash pulleys, for example), give the pieces a warm bath in a mixture of water and a linseedoil soap, such as Allback (from Solvent Free Paint, solventfree paint.com). A retired slow cooker comes in handy. Add enough water to cover the rusty parts, then put in a few squirts of the linseed-oil soap. Mix with a stirring stick, turn the slow cooker to high, and allow the parts to bathe for three or four hours so that they are fully coated. Allow the treated metal to dry for 24 hours before using or reassembling.

PENETROL

An additive that makes oil-based paints flow smoothly, Penetrol (flood.com) is also an excellent coating to keep metals protected from the elements. It displaces water, and creates a soft, protective layer that inhibits rust. After application, allow to dry for at least 24 hours. Apply multiple coats as needed.

CLEAR-COAT LACQUERS

There are many varieties of spray- or brushon lacquers that effectively coat and inhibit rust on metal. Look for a lacquer formulated for the application you have in mind (UV protection, salt corrosion, etc.). Some require that the surface be primed before using, but one, Permalac (permalac.com). can be applied directly to bare surfaces.