Paint issues from the spray gun nozzle and is accelerated by the airstream in which it divides into filaments which extend and break up. Failure of the filaments to break up or “atomize” is known as cobwebbing.
Paint is beyond pot-life.
Reduce air pressure and / or viscosity until cobwebbing disappears.
NOTE: Some specialised materials, tank linings for example, are difficult to atomise and require special equipment to be sprayed successfully.