When it comes to selecting a spray gun, the most important selection you make (after the type of spray gun itself) is the nozzle size. The nozzle, more than anything, determines how effectively the material will be atomized. This in turn determines the quality of the coating that you will get out of the spray process. The general rule of thumb is that the higher the viscosity of your material, the larger the nozzle size you need. If you go too small, you are choking off the material supply and will not get adequate coverage. Conversely, if you go too large, you are wasting material because there is not enough air to atomize the amount of material coming out of the nozzle.
There are general rules of thumb to nozzle sizing when it comes to working with paints, stains and clear-coats. However, the lines begin to blur a little when dealing with other materials such as mold release, different types of adhesives, abrasive media, marking ink, etc. This is especially true because with these types of materials because you are also looking at different needle & nozzle types in addition to sizes.
In these cases, it is important to have a test facility with access to the equipment and material in order to determine a correct nozzle size for your particular coating application.
Jorge Flores, Marketing Coordinator
Coating Equipment Technology, Inc