Electrostatic Coating for Wood Furniture

Electrostatic spray coating is the development of the conventional spraying application. The electrostatic spraying equipment is the modification of the spraying equipment to give better efficiency material transfer, especially for small surface objects. The electrostatic spraying equipment works to make the finishing material be attracted by electrical force and then wrap the object. The electrostatic spraying equipment has a tool to charge the finishing material to be the electrically charged objects. While the sprayed object is grounded to act as the other electrical object. When the finishing material is sprayed, there will be an electrostatic attraction force between the finishing material and the object. The attraction force will bring the coating material to the object and wrap the object all over the surface. 

The manually spray application technique that could produce the finishing layer with the best result has disadvantages. It gives a low efficiency of material transfer. The efficiency of the spray application is about 30%–60%, and this figure will be even lower if the sprayed object has a small surface. If the spray spreading of the spray gun is wider than the surface area of the painted object, then the more material spreads to the air as dust spray. Small surface objects such as a crib, chair, rattan, posh, and chair are wasting more material in the application. The electrostatic spraying equipment is the development of conventional spray to increase the transfer efficiency of finishing material. With good setting, the equipment will help to increase the transfer efficiency to be about 80%. 

To work with the electrostatic spraying equipment, the finishing material must be adjusted to give the electrical charge. The special additive is added in the mixture to increase its electrical resistivity. The high electricity resistivity material will make the material have a higher electrical charge to the object when it is electrified in the electrostatic spraying equipment. The electrostatic finishing materials are only available in the film-forming material, such as sealer, top coat, enamel, or base coat. The finishing materials that do not form film coating, such as wood stain and glaze, cannot use the electrostatic equipment. 

How to set and run spray electrostatic coatings.

• Check resistivity of material

Check and measure the resistivity of the material mixture; make sure it matches 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, you can use the solvent that has high resistivity, such as butyl acetate or xylene. But usually the paint company also adds some additive to increase the resistivity. 

• Check the viscosity

Spray guns 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.

This equipment still needs a spraying process to send the material to the object. If the spraying is done manually, then a good operator is needed. If the automatic spray machine is used, then a proper setting is needed. You don’t need to spray overlapping as the conventional spray technique. You 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. You need to adjust the spray gun movement to get the maximum result.

The things need to be considered when using the electrostatic spray equipment.

Even this equipment helps to improve efficiency, but the machine has some conditions to make it work well. Here are some things to consider to get the maximum benefit from the equipment.

• High cost in initial investment and maintenance

The equipment is quite complex and more expensive than the conventional spray. Not only in the initial purchasing, the machine is also more costly and complex. It needs regular checks and balances to ensure optimal performance. The special components that are needed, such as nozzles and electrodes, can wear out and need replacing, adding to the operational costs.

• Technical Complexity

Operating electrostatic spraying equipment requires a certain level of technical expertise. Users must understand the mechanics of the system, including adjustments for voltage and the control of droplet size. Improper handling or calibration can lead to uneven coverage, reduced efficacy, and wasted materials. The equipment will need skilled operators to make it run well. Some additional training may be needed to get the skillful operator until he can run the machine properly.

• Safety

The use of high-voltage electricity in electrostatic sprayers poses safety risks, including potential electric shocks and fires if not handled correctly. The proper handling and maintenance are needed to minimize the risk of fire.

• Material compatibility

Not all substrates can be effectively used in electrostatic sprayers. The machine has a lot of success stories for the metal objects but not for the wood objects. In many cases, the wood does have enough electrical charge that is needed to make the process work well. The machine is also more useful for the small components, such as legs, rattan furniture, posh, and other objects with small surfaces. The equipment does not give worth benefit to coat the component with big surface such as : cabinet, table, and other big dimension product..