White Vinegar:
Clean the inside of a steam iron by pouring white vinegar, or similar vinegar and water (50/50) in the water reservoir until it is one-third full.
Turn it on (medium-high heat setting) and let it steam for about 5-10 minutes so that all the vinegar evaporates.
Maybe a water clean afterwards, but i don't do it.
Should do the Job.... just did last week myself.
Judge., July 2017