Sometimes it is difficult to understand which paint is best for which job. 1K paint (or 1 Pack paint as it is also referred to) is a more average used paint which is suitable for common use, whereas a 2K paint (2 Pack paint) is a lot harder wearing paint which is designed to withstand weathering, general abrasion and certain chemicals. Here is a little breakdown.
1K (or 1 Pack) is a term used to describe a paint coating that does not require any hardener, catalyst or activator to cure. This term can be used to describe paints that dry in the air (ideally at room temperature) and nearly all aerosol spray can paints.
2K (or 2 Pack) describes coatings that require a hardener, catalyst or activator, which is commonly used in car body shops. Once it hardens, it provides a much stronger substrate less susceptible to damage from chemicals, weather, abrasion or UV rays. 2K Paint cans generally have the activator stored in a separate compartment, that will need manually releasing.
2k paints are not to be treated lightly as it carries Isocyanate, which can be incredibly harmful to your health if the correct precautions are not taken. It is well worth taking the time to invest in a good quality mask which is suitable to withstand a 2K product. Ensure nobody is within the area when you are planning to spray and once you have completed spraying open up the area to flush out the contaminants. For more information, please take a look at Health & Safety Executive.