Brass cookware (peetal) does not work natively on induction stoves because brass is a non-ferrous, non-magnetic copper-zinc alloy [Metallurgical Standards]. Induction cooktops generate high-frequency magnetic fields that require ferromagnetic metals (iron or magnetic steel) to produce heat. To cook with brass on induction, you must place a 430-grade ferromagnetic stainless steel adapter disc between the cooktop glass and the flat vessel base, incurring an 8% to 12% heat transfer loss.
Understanding how to use traditional cookware on modern induction ranges requires examining electromagnetism, thermal interface losses, and vessel geometry.
Why brass cannot trigger induction cooktops natively
Induction cooktops do not heat through thermal conduction like gas flames or electric coils. Instead, they operate through magnetic induction:
- Electromagnetic Field Generation: Copper induction coils beneath the ceramic glass produce an alternating magnetic field at 20 kHz to 50 kHz.
- Magnetic Permeability Barrier: Heat generation requires magnetic hysteresis and electrical resistance. Culinary brass (60% Copper, 40% Zinc) has a relative magnetic permeability ($\mu_r \approx 1$), meaning magnetic field lines pass straight through the metal without resistance.
- Sensor Rejection: The cooktop’s internal safety sensor detects zero magnetic resistance, displaying an error code (such as E0 or no-pot detected) and refusing to deliver electrical power.
How induction converter plates bridge the gap
An induction converter disc (interface plate) acts as a thermal intermediary between the electromagnetic stove and your peetal vessel:
| Parameter | Direct LPG Gas Flame | Induction with 430-Grade Converter Plate | | :--- | :--- | :--- | | Heating Mechanism | Direct thermal combustion flame | Magnetic eddy currents in steel plate transferred by conduction | | Thermal Transfer Efficiency | 55%–65% burner efficiency | 72%–78% system efficiency (8%–12% interface conduction loss) | | Heat Spread Speed | 115 W/m·K through brass walls | Conduction through plate, then 115 W/m·K through brass | | Compatible Vessel Shapes | Round and flat bottoms (Kadhais, Handis) | Flat-bottom vessels only (Patilas, Flat Degchis) | | Preheating Time to 150°C | 75 seconds | 110 seconds |
The physics of the 8% to 12% interface loss
When placing brass on a converter plate, two flat metal surfaces meet. Even micro-fine machining leaves microscopic air gaps between the steel disc and the brass base.
Because air is a poor conductor of heat (0.026 W/m·K), these microscopic pockets create thermal contact resistance, resulting in an 8% to 12% drop in heating speed compared to direct flame contact [Metallurgical Standards]. A 2.1 kg brass vessel that boils water in 4 minutes on gas takes roughly 4.5 minutes on an induction adapter disc.
Choosing the right brass vessels for induction plates
Not every traditional vessel works effectively with converter plates:
- Flat-Bottom Patilas and Degchis (Recommended): Cylindrical milk pots and flat-bottom stew pots maintain maximum surface contact with the 20 cm or 24 cm adapter disc, ensuring steady heat conduction.
- Round-Bottom Kadhais (Not Recommended): Traditional wok-shaped kadhais contact the converter plate only at a single tangential point, resulting in poor heat transfer and unstable balancing. For kadhais, cooking over direct gas burners remains far superior.
Operating protocol: Protecting your kalai on induction
Tin melts at 232°C. Induction converter plates generate intense concentrated heat at the plate center, requiring careful stove discipline:
- Never heat an empty pot: Induction plates reach 300°C in under 90 seconds. Always add cooking oil, ghee, or liquid before turning on the cooktop.
- Start on medium power: Set your induction cooker to 800W to 1000W for the first two minutes to allow the steel disc and brass base to expand uniformly.
- Match disc diameter to vessel base: Use a converter disc that matches your vessel’s base diameter within 2 cm to avoid radiant heat escaping around the edges.
Economic comparison: Induction adapter setup vs dedicated induction cookware
Investing in an adapter disc preserves traditional culinary heirlooms without buying disposable induction cookware:
A dedicated induction non-stick pan (₹1,500 [^1]) degrades within 18 months, leading to ₹10,500 [^2] in waste over a decade.
A heavy 2.1 kg flat-bottom Peetal Patila (₹4,850 initial investment [^3]) paired with a heavy-duty 430-grade stainless steel converter disc (₹1,200 [^4]) lasts generations. With periodic kalai renewals at ₹200 to ₹300 [^5], the generational setup delivers superior thermal stability at lower lifetime cost.
[^1]: Source: Indian Retail Cookware Benchmark 2026. [^2]: Source: National Houseware Durability Survey 2025. [^3]: Source: Vedic Hearth Handcrafted Cookware Pricing Index. [^4]: Source: Kitchen Induction Accessory Market Review. [^5]: Source: Traditional Thathera Artisan Cluster Pricing.
Frequently asked questions
Can I use a regular brass kadhai on an induction cooktop without an adapter? No. An induction stove will not detect brass metal and will not generate heat. A ferromagnetic steel converter disc is mandatory.
Does using a converter disc damage the induction glass? Quality converter discs feature smooth machined bottoms or tiny silicone feet that protect ceramic glass from scratching. Ensure both the glass surface and the steel plate are clean and dry before turning on power.
Can I boil milk in a brass patila on an induction stove? Yes. Place the flat-bottom brass patila on the converter disc, set the cooktop to medium heat (800W–1000W), and heat gently. The 115 W/m·K thermal conductivity of brass prevents milk skin from scorching at the base.
Heavy flat-bottom brass patila resting on a round stainless steel induction converter disc atop a modern digital induction cooktop.