The clear plastic seals on the needles don't hold up to alcohol. I purchased this HVLP system for the express purpose of spraying shellac with it. I brought it home and used it with some tinted, 1.5 lb. cut shellac, with good results. After I was done, I cleaned the gun as per the instructions - put alcohol in the cup, sprayed for a few seconds, then cleaned everything with warm soapy water. The next day, I reassembled the gun and prepared to spray a second coat. As soon as I flipped the power switch, shellac started leaking out from under the gun, around the trigger area, making a mess on my shop floor. I immediately stopped, cleaned everything, carefully reassembled the gun and tested things again with water - same leak.
So I called Earlex support, who diagnosed the problem as a bad gun and sent me a replacement. The problem was still there with the new gun, so we came to the conclusion that my needle's plastic seal must have been defective. They sent me a new needle and I was able to spray my project's second coat. Halfway through the third coat, however, the leak started up again! Clearly the plastic seal is not friends with the alcohol in the shellac...
So Earlex is sending me a third needle (I must say their customer service is good - I'm giving this review two stars instead of one for this reason alone), along with instructions to use less alcohol and more soapy water when cleaning it, and to put it back in the gun as soon as it's cleaned: apparently just letting the needle rest on a flat surface under its own weight is enough to deform the seal and damage it! Something tells me I'll be calling Earlex again next week...