Orange peel is a common texture issue that can occur during the painting process, particularly when using turbine HVLP (High Volume Low Pressure) spray equipment for bathtub refinishing with two-part polyurethane and epoxy coatings. This effect is named for its resemblance to the texture of an orange peel, characterized by a slightly bumpy surface rather than a smooth, glossy finish.

Here's how orange peel can happen in the bathtub refinishing industry:

1. Spray Technique: Inconsistent or improper spraying techniques can lead to orange peel. Factors such as spray gun distance, speed of application, and angle of spraying can affect the texture of the applied coating.
2. Viscosity of Coating: If the coating material is too thick or too thin, it can contribute to orange peel. The viscosity of the coating material should be adjusted according to the manufacturer's recommendations and environmental conditions.
3. Temperature and Humidity: Environmental factors such as temperature and humidity can impact the drying and curing process of the coating. High temperatures or low humidity levels can cause the coating to dry too quickly, leading to orange peel.
4. Spray Equipment Setup: Improper setup of the spray equipment, including incorrect air pressure, nozzle size, or fluid flow, can result in orange peel.

To avoid orange peel in bathtub refinishing:

1. Practice Proper Spray Technique: Train technicians in proper spraying techniques, including maintaining a consistent distance from the surface, using even strokes, and overlapping each pass slightly.
2. Adjust Coating Viscosity: Ensure that the coating material is mixed and thinned to the correct viscosity for optimal spraying. Follow the manufacturer's guidelines for mixing ratios and thinning agents.
3. Control Environmental Conditions: Maintain controlled environmental conditions in the spraying area, including temperature and humidity levels, to promote proper drying and curing of the coating.
4. Regular Maintenance of Spray Equipment: Keep spray equipment clean and well-maintained to ensure consistent performance. Check and adjust air pressure, nozzle settings, and fluid flow as needed.

If orange peel does occur, here's how to repair it:

1. Sand the Surface: Use fine-grit sandpaper (e.g., 800-1000 grit) to sand down the orange peel texture until the surface is smooth.
2. Apply Additional Coats: Apply additional coats of the coating material, following proper spraying techniques to achieve a smooth finish.
3. Leveling Agent: Some coatings may benefit from the use of leveling agents or additives to help minimize orange peel and improve the flow and leveling properties of the coating.
4. Buff and Polish: After the coating has cured, buff and polish the surface to restore the gloss and achieve a uniform finish.

By focusing on proper technique, material preparation, and environmental control, bathtub refinishers can minimize the occurrence of orange peel and achieve high-quality, glossy coatings. Regular training and maintenance are essential for consistent results in the industry.