Technical
Induction: the magnetic layer is the whole product
An induction hob does not heat the pan; it heats the steel in the base. If the magnetic layer is wrong, everything else about the pan is irrelevant on that hob.
At a glance
Specification at a glance
| Variable | Effect on induction performance | Practical guidance |
|---|---|---|
| Base grade | Ferritic grades work; austenitic do not | 430 is the standard base face |
| Base thickness | Thin layers heat unevenly and can warp | 0.4 mm and above, per pan size |
| Pattern on the base | Reduces the contact area if too deep | Ask for base pattern depth separately |
| Flatness of base | Poor contact means poor coupling | Flatness limit on the base face, not just the disc |
| Pan diameter vs hob ring | A base smaller than the ring heats unevenly | Match the base to the hob, not the rim |
How the hob sees the pan
An induction coil generates an alternating magnetic field, and the field induces eddy currents in a ferromagnetic material. The base heats, the food heats from the base. A 304 face does not respond to the field at all, which is why a two-layer stainless-aluminium pan is invisible to an induction hob.
How thick the magnetic layer needs to be
There is a threshold below which coupling is weak and the pan heats slowly and unevenly, and there is a point beyond which extra thickness adds nothing but weight. In cookware, 0.4 mm is the usual floor for a 430 base, with heavier bases in larger pans.
The number that matters is the base's, not the total gauge: a 3.0 mm pan with a 0.25 mm magnetic layer is a worse induction pan than a 2.4 mm pan with 0.5 mm.
Flatness is part of the electrical circuit
A dished base sits on the hob with an air gap, and the gap breaks the coupling. This is why induction pans are specified for base flatness, and why a pan that works when new can stop working after a few months of hard heating if the base warps.
Patterns, coatings and other traps
A pattern rolled into the base reduces the effective contact area and can change performance. A thick coating acts as a spacer between the base and the glass. Neither is fatal, but both have to be considered together with the base thickness, not after it.
Questions
Common questions
Will a 2-ply pan work on induction?
Not without a magnetic layer. A 2-ply stainless-aluminium pan has no ferromagnetic face, so induction needs a separate magnetic base or a 3-ply structure.
How can I test if a pan is induction capable?
A magnet on the base is the quick test. If it sticks firmly, the base is ferritic and the pan will couple with an induction hob.
Does a thicker magnetic layer heat faster?
Up to a point it heats more evenly rather than faster. Beyond the threshold the benefit is stability, and the cost is weight.
Why does my induction pan heat unevenly at the edges?
Usually because the base is larger than the hob ring or slightly dished. The coil only couples where the field is strong and the base is in contact.
Can the magnetic layer be on the inside?
No. It has to face the hob. The cooking face is 304, the base is 430, and the order is fixed by physics.