The spray application technique that could produce finishing layer with the best result has disadvantages, that is the low efficiency of material transfer. The spray application will give material transfer efficiency about 30%-60% and this figure will be even lower if the sprayed object has small surface. If the spray spreading of the spray gun is wider then the surface area of the painted object, then the more material spread to the air. Small surface objects such as: crib, chair, rattan, posh, chair are wasting more material in the application. The electrostatic spraying equipment is the modification of the spraying equipment to give better efficiency material transfer especially for the small surfaces object. ( the electrostatic spraying equipment)
The electrostatic spraying equipment work by charged the finishing material to be the electrically charged objects. While the sprayed object is grounded to act as the other electrically object. When the finishing material is sprayed there will be electrostatic attraction force between the finishing material and the object.
To work with the electrostatic spraying equipment we need special finishing material, it is the electrostatic coating material. The electrostatic coating is the coating that will act as an electrically charged object when it is given the electric charged.
The electrostatic coating is regular coating that is added with some additive to increase its electrical resistivity. The high electricity resistivity material will make the material become better electrically charge object when it is electrified in the electrostatic spraying equipment. The electrostatic finishing material are only available in the film forming material such as sealer, top coat, enamel or base coat. The finishing material that dose not form film coating such as: wood stain and glaze are never work with the electrostatic equipment.
How to use electrostatic coatings.
- Check resistivity of material
Check and measure the resistivity of the material mixture, make sure it according with the resistivity needed by the spraying equipment. The measurement can be done using the ohm meter.. In general, the higher resistivity material is better since it will generate more electrostatic charge. To increase the resistivity in the mix we can use the solvent that has high resistivity such as Buthyl acetate or xylene. But usually the paint company has added some additive to increase the resistivity. We also can add some more additive if necessary.
- Check the viscosity
Spray gun used in electrostatic equipment will work properly only when the material has proper viscosity. Check the viscosity of the mixture; make sure it is according to the specifications of the spraying equipment used. Use special thinner to reduce the mix since the thinner will affect the electrical resistivity of the solution
- Spray techniques.
In the electrostatic spraying equipment, the finishing material will be attracted and wrap the object. We don’t need to spray overlapping as the conventional spray technique. We can reduce the spray gun stroke to get the same result with the conventional spray. The spray techniques should be simpler and easier. The spray gun distance also cannot be too close. We need to adjust the spray gun movement to get the maximum result.