Cast Iron Heat Rings and Notches: What They Tell You
The heat ring is the raised ridge on the bottom of many older skillets. Whether a pan has one, where it sits and whether it has gaps are among the most useful clues on an unmarked skillet, and they help date marked ones too. Read the ring with the pan bottom up and the handle at 6 o'clock.
Three things to check
- Is there a ring at all? Makers dropped heat rings from most sizes as cooktops modernized, so a smooth bottom often means a later pan.
- Where is it? An inset ring sits a little way in from the edge. An outside ring runs right at the edge.
- Is it broken? Count any gaps (notches) and note their clock positions.
What the patterns point to
| What you see | Points to | Dates |
|---|---|---|
| Inset ring, one notch at 12 | Lodge single notch | 1930s |
| Inset ring, notches at 9, 12 and 3 | Lodge three notch, or a copy of it | 1940s–1987 |
| Scalloped ring of crescent segments | Believed to be Lodge of the same period as the single notch | 1930s |
| Inset ring, unbroken, size number at 6 | Birmingham Stove & Range | 1930s–1960s |
| Outside ring, sideways number at 3 | Vollrath | — |
| Outside ring, size on the handle, molder's letter at 6 | Early Lodge (“Blacklock”), an unproven attribution | 1900–1910 |
Rings on marked skillets
Griswold. Early skillets and the large block logo era used inset heat rings. Small block logo skillets (1939–1957) have smooth bottoms, except sizes 12 and up, which always kept a ring. A small block logo on a ringed No. 8 would therefore be a contradiction worth investigating.
Wagner. The Wagner Ware stylized logo appears centered on heat-ring skillets in sizes 4 to 8, roughly 1924–1935, and high on the base of smooth-bottom pans.
Why a ring is never proof on its own
Three notches suggest Lodge, but other foundries copied them. In one documented case collectors rejected a Lodge attribution for a three-notch pan because its handle was a style Lodge never used, and its small pour spouts and reinforced rim pointed to automated molding from the 1960s or later. Check the handle and the size number before you settle on a maker.
Sources: The Cast Iron Collector: Identifying Unmarked Iron · The Cast Iron Collector: Evolution of the Griswold skillet · The Cast Iron Collector: Evolution of the Wagner trademark · Cast Iron Collector forum: three notch with no markings
Updated 2026-11-10. How we check and correct this site.