Tommee Tippee Closer to Nature Complete Feeding Set, White. Note: Descaling steriliser- Always unplug the appliance and wait until it has cooled down completely before descaling. 1. Empty the steriliser and wipe inside with a sponge or damp cloth 2. Pour in 1 cup (250ml) of white vinegar and leave for between 30 mins and 24 hours, depending on the extent of limescale 3. Pour any remaining liquid down the sink and rinse with cool water. Use a sponge or cloth to remove any loose bits of limescale 4. Plug your steriliser back in, adding the regular volume of water for a normal cycle. 5. Turn on and run for 5-minutes then give a final rinse. Note : To remove the black spot 1) scrubbing the heat-plate with something like an abrasive scourer to clean or remove limescale; 2) using a harsh “limescale” remover that contains chemicals that react with the coating (e.g. bleach or high acid concentration). We recommend descaling regularly (before scale builds up) with white vinegar only as it is gentle, natural and are unable to replicate the wear (1,000 cycles) on the heat-plate seen when using other so-called “descalers”.