Needle/tip size has more to do with Flow Rate than viscosity. Select your smaller 1.3mm tip/needle combination for smaller parts or cut in's, and conversely, the larger 1.3 for larger areas. As already stated, use the minimum amount of reduction as possible, and yet still achieve good atomization. Keep in mind that HVLP yields about 50% Transfer Efficiency, i.e., half of your paint is waisted in overspray. Reduction reduces paint solids by weight/volume, further reducing efficiency. More coats will be needed to build film. For example, if you desire 1 mil of dry paint, and your reduced paint was 25% solids to water/solvent, then you would need to apply 4 mils of wet paint to end up with 1 mil of dry paint. Thus two coats of paint, 2 mils wet per coat!
Adjust your Atomization Air to dial in particle size, and your Fan Air to for your pattern size. Dial in to a nice oval shaped pattern. For a good reference, Google: The ABC's of Spray Equipment, it was published by the DeVlbiss Company who as it turns out, invented spray atomization! Almost all spray gun manufacturers today have great online resources, use them to learn, and then practice!
By the way, viscosity cups really don't work very well with Newtonian (viscosity changes under shear) fluids like latex paints. For most, unless you have a Brooksfield viscometer, that means, reduce the minimum need ed to achieve good atomization, small paint particles when spraying a test pattern.
I realize I threw a lot at you here, but learning to spray paint can be rewarding, useful, and fun!
Sent from my iPad using Tapatalk Pro
