Turn off the iron and unplug it
Let it cool completely
Wipe the soleplate with a soft, damp cloth
Make a paste of baking soda and water
Apply the paste to the patch
Gently scrub with a non-abrasive sponge or cloth
Wipe clean with a damp cloth
Use white vinegar on a cloth for stubborn residue
Wipe again with a clean damp cloth
Dry the soleplate thoroughly
Test on an old cloth before using on fabric