I am polishing outdoor brass on a door and want to seal it from any future deterioration with a laquer coat. I have an acrylic laquer from Sherwin Williams for the purpose but am having diffulty getting a coat that preserved the shine. I have a compressor and a siphon feed spray gun. I have decreased the air pressure to 20 lb and the laquer is thinned 1:1 with laquer thinner. What I am getting is a matte finish.