Painting with a spray gun consists of spraying an even coat of paint onto surfaces and objects with complex or irregular shapes such as grilles, shutters, etc.
This spray is achieved with pressurized spray cans or with special guns that atomize the paint thanks to the air pressure generated by a compressor.
The spray is made up of microscopic droplets of paint; using a paint with the correct density and adequate pressure allows you to achieve an excellent result.
How to choose the equipment?
Let's look at the main options:
The electric spray gun is a self-contained, easy-to-handle and lightweight device, powered simply by plugging it into an electrical outlet. The pressure varies depending on the power of the device. Power 60/100W, Pressure 150/180 bars, capacity 250/350 g/min.
The more advanced guns have interchangeable nozzles of different diameters depending on the viscosity of the paint to be sprayed. They are equipped with an electronic flow regulation system.
Accessories: flexible extension for floor or ceiling, viscometer, nozzles, remote suction.
The compressed air spray gun is a gun that works with an air compressor. The compressed air travels from the compressor to the gun through a hose. This system does not require high pressure, ranging from 0.1 to 10 bar. It is used for large surfaces and high-quality finishing work such as automobile bodywork.
Preparation
The work area: Carefully protect all areas that are not to be painted, as sprayed paint settles everywhere. Use plastic sheets and masking tape to cover them.
The surface to be painted: The surface must be thoroughly cleaned, dry and smooth. For surface preparation.
The spray gun: Check that the gun is working properly and make sure it is not clogged. Choose a nozzle that matches the surface to be painted.
The paint: Thin the paint so it can be sprayed, with white spirit for solvent-based or polyurethane paints. With water for acrylic paint, according to the manufacturer's instructions. Check the viscosity of the paint, either directly with the gun or with a viscometer following the chart provided with the device that indicates the emptying time depending on the type of paint.
The technique
Before painting, do a test on cardboard to check the flow.
Hold the gun vertically and position it about 25 cm from the surface to be painted. Move the gun parallel to the surface in a very slow and steady motion without any wrist movement. Apply at least two coats of paint by cross-hatching the surface.
For the first coat, draw horizontal 'S' patterns; for the second coat, draw vertical 'S' patterns that overlap. Overlap each band of paint by about 1/3 of its width. Never spray paint without moving the gun, otherwise the coat will be too thick and the paint will run.
Release the trigger at each interruption of movement outside the area to be painted.
Cleaning
Clean the gun thoroughly as soon as the job is finished.
Empty the paint cup, fill it halfway with solvent and spray onto newspaper, then clean the cup, the gun fittings and the inside of the nozzle.
Remove the nozzle and clean it with a small brush.
Clean the outside of the gun with a cloth soaked in solvent.
In the case of an electric gun, put a little vaseline oil in the bottom of the cup and spray for a few seconds.
The oil settles on the mechanism and lubricates it until the next use.
