Combine the primary colors and adjust with a paint reducer/thinner.
NOTE:
The viscosity of water-based paint is adjusted by adding reducer or paint thinner exclusively for the water-based paint.
There are several types of reducer; such as standard type and slow-dry type. Select the most appropriate type depending upon the ambient conditions and accurately measure the required amount.
When too much reducer/thinner is added, coverage capability is reduced. Selecting the wrong type of reducer/thinner, greatly increases drying time, slowing your work efficiency. Confirm the product spec information issued by the paint manufacturer.
Coating Condition
NOTE: The setting of your spray gun has significant impact on the finish quality. Make sure to apply the correct settings after confirming the production spec information issued by the paint manufacturer.
Settings for Low Pressure Spray Gun (Example):
Air Pressure
Block Paint: 130?200 kPa (1.3?2.0 bar, 20?30 psi)
Gradation Paint: 150?180 kPa (1.5?1.8 bar, 22?26 psi)
Removal of Unevenness: 130?150 kPa (1.3?1.5 bar, 18?22 psi)
Discharge Rate: Open 3 to 3.5 turns from full close
Pattern: Open 3/4 turn from full close
Spray Distance: 15?20 cm (6?8 in)
The setting value will change depending on the size or shape of the coating surfaces.
2.
Sanding and Degreasing before Topcoating:
Scuff with P600 to P800 sandpaper.
Degreasing should be done in two steps; one with solvent type degreaser and another with water-based type degreaser.
3.
Water-Based Color Basecoating:
?1.
Apply medium coat so that the entire surface will be lustered.
NOTE: Apply in thin coats or the water won’t be able to escape from the paint film, reducing your work efficiency. In addition, thickly applied paint layers may become whitish.
?2.
Dry the color basecoat. After allowing sufficient flash time, use a portable air blower/heat gun to completely remove water content from the paint layer until it has a flat appearance.
NOTE: Refer to the paint manufacturers’ instruction for the appropriate flash time and drying temperature.
NOTE: Flash time can be greatly impacted by the ambient humidity.
Comparison of Flash Time (Example): Conditions (in paint booth for water-based paint)
Coating Surface: Door Panel
Color: Silver Metallic
Dilution Rate: 20%
Coating Condition: Block Coating
Ambient Conditions: Temperature 70 °F (21 °C)/Humidity 60% RH
No.
Drying Location
Flash Time
1
Below the booth fan
8 min 41 sec
2
Away from the booth fan
10 min 15 sec
3
Below the booth fan with air blower
3 min 35 sec
Same as above conditions 30% RH humidity
2 min 10 sec
?3.
Repeat the processes of -1. and -2. (coating and drying) and layer the color base to cover the surface completely.
NOTE:
Normally spray 1 to 2 times to cover the surface.
Gradually widen the coating area at each layer when applying gradation coating.
When foreign substances adhere to the surface, dry sand with a sandpaper of P1000 or higher after complete dry. Do not wet sand.
?4.
Remove unevenness. Color unevenness rarely occurs, so apply as needed.
NOTE:
When removing unevenness, place the spray gun a little further away from the surface being painted and spray with a lightly lower pressure.
Apply light coat for gradation coating.
Confirm the paint manufacturers' instructions. Some paint may require use of exclusive paint reducer/thinner for the gradation paint.
4.
Drying Topcoated Layer: Allow sufficient set-up time and let the color base completely dry.
5.
Clearcoating: Generally apply two coats, allowing it to match the adjoining panel’s surface quality.
NOTE: After the first light coat, allow flash time and wet coat (finishing).
6.
Drying Clear: Allow sufficient set-up time before force-drying.
NOTE: Confirm the paint manufacturers' instructions for the appropriate setting time and drying temperature.
