Powder residue after spray painting happens when you paint outdoors when it is hot or in the sun.  The paint spray dries before reaching the surface and it cannot level because of too rapid evaporation.  It can also be caused if you hold the can too far away. It is better to spray in the morning or evening during the summer and keep the can about 8-16” away from the item as you spray. If it is a chandelier or large piece that has to be sprayed in sections, block off other sections while you spray one section at a time with a piece of cardboard.