This is the unenviable sticking of two painted worktop of two painted areas. Blacking may occur because the painted object was not given much time before use and so it leads to sticking of the uppermost surface of the painted area with other objects, also, blocking may occur due to use of low quality or cheap semi-gloss paints that had been used during the paint job. Blocking may also occur due to extreme wet conditions and tackiness may also be caused if paint job is done in too hot or too cold paint conditions. Also, using latex paint is an invitation to blocking.
In order to prevent blocking, you have to follow following steps: