Common cast iron defects — deal-killer vs $5 fix

Buying vintage cast iron online means grading condition from a handful of photos. The good news is that the defects that look worst — rust and thick black crud — are usually the easiest to fix. The bad news is that the defects that matter most, like hairline cracks and warps, are often the hardest to see in a photo. Here's how to sort what you're looking at.

Cosmetic — bid normally

• Surface rust. Orange rust on the surface scrubs off with steel wool or a vinegar soak, followed by drying and oiling. Check afterwards for pitting underneath.
• Carbon and crud. Thick, flaky black buildup is old seasoning and burnt grease. Most of it scrubs off; stubborn buildup comes off in a lye bath (see the restoration guide). It often hides the logo and small cracks, so ask for a better bottom photo.
• Worn or patchy seasoning. Easily rebuilt with a few thin coats of oil baked on at high heat.
• Light scratches. Shallow scratches through the seasoning disappear with re-seasoning.

Value hits — bid, but pay less

• Pitting. Small pits from old rust are common on bottoms and don't affect cooking much; pitting on the cooking surface affects release and value. Heavy pitting on the bottom can also obscure the logo and pattern number.
• Sandblasting. Blasted pans have a uniform matte grey, slightly rough surface. They cook fine once seasoned, but collectors value them less and the marks may be softened.
• Plating. Chrome or nickel plating flakes as it wears and can't be seasoned over well. Plated pans are shelf pieces or stripping projects.
• Missing lid or base. A Dutch oven without its matching lid, or a waffle iron without its base, sells for considerably less than a complete set; finding the right part later can take a long time.
• Rim and spout wear or small chips. Worth a discount, but check closely that a chip hasn't started a crack.

Deal-killers — walk away unless it's priced as a wall-hanger

• Cracks. Hairline cracks usually start at the rim or near the handle and can run across the bottom. They spread with heating and can fail without warning. Look for a thin dark line in photos, ask the seller to tap the pan while hanging from a finger — sound iron rings, cracked iron often thuds — and check again when it arrives.
• Warp. A "rocker" wobbles on a flat surface; a "spinner" has a bowed bottom and rotates on its centre. Both are permanent. A slight spinner can still work on a gas burner or in the oven, but it won't sit right on a glass or induction cooktop.
• Fire damage. Pans that were burned in a fire, often in an attempt to clean them, can show a red or pinkish tinge and won't hold seasoning well. Collectors avoid them.
• Repairs. Welded or brazed handles and cracks reduce a pan to a display piece for most buyers.

Piece-specific checks

• Muffin, gem and corn stick pans. Hold them to the light and check every cavity for a through-crack. One cracked cup or stick takes a large bite out of the value; several make the pan a display piece.
• Waffle irons. Check both paddles and the base ring for cracks, and confirm the hinge closes the paddles flat without slop or seizing.
• Dutch ovens. The lid should match the body, seat without rocking and not be cracked; check the bail ears for cracks.
• Griddles. With almost no sidewall, griddles show warp more readily than skillets — the flatness check is the main one.
• Enameled pieces. Chips through to bare iron, crazing and rust lifting the enamel are permanent and get worse with heat.