This type of discolouration is caused by high heat or hot spots that occur when you do not stir your food frequently. This discolouration can be removed with some effort. Start by soaking the stained area with lemon juice or vinegar, then scrub with a mild abrasive scrubber sponge. Rinse thoroughly and then scrub any remaining stain using Amway Home L.O.C. Soft Cleanser. Repeated cleaning may be necessary to remove these stubborn stains. You can avoid getting these heat marks on your cookware by always cooking at low to medium heat and by stirring your food frequently.