E.g., does this symbol mean do not pack the cleaned cloth in a nylon envelope, or does it mean no dry cleaning? Is this an artificial heat source, or "natural dry"? Or is it the smelly process (bleaching)? Is this a closed chemical or recycling process, or tumbling? Also, the dot system is probably easier to identify and discern and more resistant to wear than the depiction of thermometers (which probably only work relative to each other, having something to compare with).
Moreover, icons like these are not app icons on the home screen: they do not work best, if they (or their constituting elements) are all of even weight. Eye-sight, lighting conditions and ease of identification are primary aspects of this. Something like this should probably work by a primary context identifier, conveyed by the shape, and a secondary qualifier ("specificator") inside that shape with convenient separating whitespace around it.