Dry Steam and Wet Steam
In the simplest terms, steam is the vapor that is produced as heated water changes from a liquid to a gas. Depending on the temperature of the vapor, steam may contain suspended droplets of liquid water or it may consist entirely of gaseous water. Steam that is at or near water's boiling point, 212 degrees Fahrenheit, will contain a relatively high percentage of liquid water; this vapor may be referred to as wet steam. Steam that is heated to a higher temperature, above 240 degrees Fahrenheit, will contain only 5 to 6 percent liquid water and is often called dry steam, vapor steam or superheated steam.
Vapor Steam Cleaners
Vapor steam cleaners use an integrated boiler to heat water to high temperatures, usually between 240 and 290 degrees Fahrenheit. This produces a very dry steam that can be used to clean a very wide range of surfaces. Vapor steam is used in many different types of floor cleaners, ranging from small consumer-oriented steam mops to large industrial vapor steam cleaners.
Wet Steam Cleaners
Wet steam cleaners do not heat water to as high a temperature as do vapor steam cleaners, which means that the steam they produce contains a higher percentage of liquid water and they tend to saturate the surfaces they clean with water. These types of cleaners often incorporate a vacuum action that removes the water introduced by the steam. This process of steam injection followed by the extraction of water is crucial in the effectiveness of these cleaners.
Because the cleaning process of vapor steam mops is drier than that of wet steam cleaners, vapor steam mops are better suited to cleaning surfaces that might be damaged by excessive moisture, such as wood and laminates. The higher temperature of dry steam is also better able to sanitize surfaces by killing bacteria and mold spores. Wet steam cleaners are better suited to deep cleaning of materials such as carpet that can stand up to the combination of heat and moisture.