used as aqueous paint a coating machine and an article to be coated aqueous paint ade recycle f 2000 tms black available from nippon paint co ltd article to be coated 0 8 mm steel panel spcc sd untreated panel in examples 1 to 6 surrounding temperature and relative humidity before spray coating were determined by temperature and humidity detectors each known to the art from which each allowable volume absolute humidity y was obtained a paint temperature x was calculated from the equation using the allowable volume absolute humidity y in order to put the present invention to practice use aqueous paint provided to the portion of the spray gun is temperature controlled within the optimum temperature range in a short period of time before spray coating in response to coating conditions changing with time therefore information obtained from the temperature and humidity detectors is input into a computer and calculated from the above mentioned equation to obtain optimum paint temperature and a temperature of the spray gun tip was adjusted by the computer system from the data input in the computer spray coating was conducted using the temperature controlled spray gun onto the article to be coated and dried at 60 u00b0 c for 20 minutes in case where the paint.