A kitchen tawa is made to last for years, used almost every day to make rotis, parathas, dosas and chillas. But how do you know when your trusted cooking utensil has reached the end of its life? Sometimes, your food may give you the first clue.“When it comes to replacing the kitchen tawa, your rotis often tell you before your eyes do,” said Kanikka Malhotra, dietitian and certified diabetes educator.If you use a non-stick tawa, look for deep scratches that expose the grey metal underneath, peeling or bubbling coating, and food that sticks even when you use oil. Dark patches that refuse to wash off are another warning sign.For any type of tawa, check whether the base has warped. Place it on a flat surface and press the edges. If it rocks, the base may not be making even contact with the flame, causing rotis to burn in some places while remaining undercooked in others.Other red flags include a loose handle, cracks and a burnt or rancid smell that persists even after washing.DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. “A simple test: if you need more oil every month to stop sticking, the coating or seasoning is gone,” Malhotra said.Story continues below this adHowever, a rusty iron tawa does not automatically need replacing. Rust can be scrubbed off, and the pan can be dried and seasoned again.Is it safe to use a scratched or peeling non-stick tawa?A scratched non-stick coating is not necessarily as dangerous as some headlines suggest, but overheating is a genuine concern.“The slippery black layer on a non stick tawa is a type of plastic coating, often sold under the brand name Teflon. It is very stable, and tiny flakes that get swallowed generally pass through the gut unchanged,” Malhotra explained.Laboratory studies have found that scratched coatings can shed microscopic plastic particles, although their effects on human health have not been established.Story continues below this adThe more immediate concern is overheating. According to Malhotra, non-stick coatings can begin to break down and release fumes above roughly 260°C. These fumes can cause a short, flu-like illness in people and can be fatal to pet birds.An empty tawa on a high flame can reach such temperatures within minutes. Malhotra recommends keeping the flame at medium, particularly when preheating the pan.Once a non-stick coating is badly worn, the underlying aluminium may come into contact with food. This is a particular consideration for people with kidney disease. Very old or unbranded pans may also have been manufactured using PFOA, a chemical phased out around 2015.How long should different types of tawas last?There is no fixed replacement schedule. The material, frequency of use and condition of the cookware all matter.Story continues below this adNon-stick tawa: Around two to five years with daily use. Frequent high-heat cooking, poor-quality coatings and abrasive utensils can shorten its lifespan.Cast-iron tawa: It can last for decades with proper care. Rust and stickiness can often be addressed through cleaning and seasoning. Replace it if it develops cracks, severe warping or deep pitting.Stainless-steel tawa: It can last ten years or more. Warping, severe pitting or separation of its layered base may mean it is time for a replacement.“Go by condition, not the calendar, but lifespans differ hugely,” Malhotra said.Story continues below this adThe cost can also add up. Replacing a non-stick tawa every two years can cost more over a decade than investing in a good cast-iron tawa that lasts for years.Also Read | Iron kadhai vs stainless steel vs non-stick: Benefits and safety of different cooking vesselsDoes rust or other damage affect food safety?Rust on an iron tawa is generally not, by itself, a reason to discard it. Malhotra explained that small amounts of iron oxide are not toxic. Tetanus is caused by bacteria entering the body through wounds, not by rust itself or by eating food cooked on a rusty surface.The greater concerns are cracks, deep pits and peeling coatings, which can trap oil and food residues. A thick layer of burnt carbon can also flake off into food, while high-temperature cooking of starchy foods can form acrylamide.Cookware quality matters, too. Malhotra cautioned that studies of some unbranded recycled aluminium cookware have found lead leaching, making it important to buy from a reputable manufacturer.Story continues below this adHow can you make your tawa last longer?The right maintenance routine depends on the material.For cast iron, wipe off food residue, rinse with warm water and a soft brush, then dry the tawa immediately over a flame. Rub on a thin film of oil to protect the surface from rust. Avoid soaking it overnight.For non-stick cookware, let the tawa cool before washing it. Use a soft sponge and wooden or silicone spatulas, and avoid steel wool. Aerosol cooking sprays can leave behind residue that is difficult to remove.For stainless steel, simmering water in the pan can loosen stuck food. Baking soda can help with scrubbing.Story continues below this adWhatever the material, store tawas in a dry place and place a cloth between stacked pans to prevent scratches.Malhotra recommends matching the tawa to the cooking method. Dry heating a non-stick tawa for rotis can be particularly hard on its coating, while a seasoned iron tawa is suitable for rotis and a non-stick one can be used for chillas.Preheating gently over medium heat, rather than heating an empty pan over a high flame, can also help prevent damage.For a new iron tawa, Malhotra recommends scrubbing it, applying a thin film of oil, heating it until the oil just begins to smoke, allowing it to cool and repeating the process two or three times. Fermented batter and tomato-based dishes can affect the seasoning, so wipe on a fresh film of oil after cooking them.Story continues below this ad“The traditional cut onion rub helps clean the pan, but the oil film is what protects it,” the dietician concludes.DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to.