One thing to consider about compressor size is that if the unit is too small, it will run all the time while you're using it. It will get hot and stay hot. That will tend to put more water vapor in the compressed air. It will have less chance to cool and condense out before it gets sprayed, unless you have a system more sophisticated than the typical regulator / water trap setup. It is also possible that the heat of constant use could put vaporized oil from the compressor into the air stream. Choosing a compressor that exceeds the CFM rating of your spray gun or tools is the best plan. Horsepower is not an accurate rating. CFM at a certain pressure is.
A long list of factors affect the smoothness of your paint finish. Technique is most important. Once you get that down, take a look at your materials and equipment next. If you use a paint that dries too fast for the temperature, it will not get a chance to lay out smooth. Different clears have a built-in length of time they flow out, no matter how you spray them. Activators and reducers can adjust that somewhat. A slower drying paint just flows out better, but is more vulnerable to dirt and runs.
A big factor is atomization. The old way of thinking was to spray paint as heavy as you could and it would flow out smooth if you stopped just short of running it. The new way is to have a paint gun with very high atomization that breaks the paint into extremely fine droplets. You can then spray with less pressure, less overspray and less total materials. I have found that a good gravity feed paint gun with a 1.3 head gives great results. Your paint motion will be slower than the old way, but the finish will be smoother.
And I have to reinforce the above warnings about wearing respirators. Wear them for sure. Keep them in a zip-lock bag when you're not using them. Keep even the slightest amount of fumes out of your house and away from your family.
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Jim "Oldgas" Potts
Your host and moderator
