The orifice of a 313 spray tip is too big for achieving a fine finish. This tip size allows too much material to pass through with less atomization. If you're using a 313 Graco brand tip, it's likely the RAC 5 series. These tips aren't meant for fine finish spraying. Use a 310, or a 308, Graco FFLP tip. These tips are the color green and require the use of the blue RAC X tip guard, not the orange one. Make sure you're using the right size mesh filter in your gun and manifold filters. You want 60 mesh with enamel, not 100, 200, or 30 mesh. Emerald is very thick. You have to make quick passes with the pressure cranked up, but 2,800 PSI is a little high. Reduce your PSI to the 2,000 to 2,400 range. The orange peel was likely due to overapplying the enamel with the 313 tip and high pressure. I recommend buying an inexpensive wet mil gauge and measuring the thickness of your coating. With enamel, you want 4 wet mils. Anything beyond 4 or 5 wet mils, you're more likely to get orange peel without the right spray tip. You can also run into problems with bubbles and cratering if you overapply.