No.72: Becoming a Master Sprayer

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Guide to Mastering the Air Spray Gun – Part 2 

Key Points 

• Always check the round and elliptical spray patterns before painting.
• Adjust the air pressure, paint volume, and pattern adjustment screw according to the shape of the object being painted to avoid leaving dry mist and ensure no missed areas.
• Regular cleaning and disassembly of the spray gun are crucial to maintain the quality of painting work. Pay special attention to preventing the air cap holes from clogging.
• Implement thorough safety measures during spray operations to prevent skin contact and inhalation of organic solvents by wearing solvent-resistant gloves, a gas mask, and safety goggles.

Step 3: Spray Sequence 

The sequence of spraying significantly affects the efficiency and quality of the painting process. Generally, move the gun along the long axis of the object being painted. For instance, when painting a surface without corners, move the gun from left to right, and then from top to bottom. Conversely, when painting an object with corners or recesses, proceed from the inside to the outside and from back to front. It’s crucial to pay close attention to avoid leaving dry mist and ensuring there are no missed areas. 

Step 4: Gun Cleaning and Disassembly 

Cleaning and disassembling the spray gun are essential for maintaining the quality of the painting work. When pausing the operation, remove the air cap and soak it in thinner to prevent clogging. At the end of the work, follow these steps for cleaning: 

1. 1. Remove any remaining paint from the paint cup, add a small amount of cleaning thinner, and use a brush to clean the inside walls of the cup.
   2. Cover the holes of the air cap with a rag, pull the trigger to spray the thinner through. This process cleans the paint passage with the cleaning fluid.
   3. Dispose of the used liquid and wipe off any remaining paint inside the paint cup with a rag.
   4. Add new thinner and repeat the spraying process to discharge it.
   5. Remove the paint cup and air cap and clean the paint passage and air holes.
   6. If necessary, loosen the paint volume adjustment screw, remove the needle valve and paint nozzle, and clean the paint passage.

Ensure to carry out steps 1 to 5 thoroughly. 

Step 5: Safety Measures for Spray Operations 

Spray painting requires high safety measures. All liquid paints contain flammable organic compounds that are harmful to the human body. Avoid skin contact and inhalation of vapors. Wearing solvent-resistant gloves, a gas mask, and safety goggles is mandatory during work. Additionally, wear an antistatic dust-proof suit to prevent electrostatic discharge by the operator. Consideration for the risk of oxygen deficiency and fire when handling organic solvents is crucial. For tasks such as paint removal and sanding that do not use organic solvents, wearing a dust mask, safety goggles, work gloves, and a cap is recommended.