As a professional in the field of painting and coatings, I understand the importance of proper surface preparation and compatibility between different types of paint. When it comes to painting over a high gloss finish with a semi-gloss, there are several steps to consider to ensure a successful and long-lasting result.

Firstly, it's crucial to understand the nature of the paints involved. High gloss paints typically have a smooth, reflective surface that can be challenging to paint over directly. They are often oil-based, which can create issues with adhesion if not properly prepared. On the other hand, semi-gloss paints are also available in both oil and latex-based formulations, with latex being more common and easier to work with for DIY projects.

Step 1: Proper Surface Preparation
The first step in painting over a high gloss finish is to prepare the surface. This involves:

- Cleaning: Thoroughly clean the surface to remove any dirt, grease, or grime that could interfere with paint adhesion.
- Sanding: As mentioned in the reference material, using an 80-grit sandpaper is a good starting point. Sanding helps to roughen the surface, which can improve the adhesion of the new paint. However, it's important to sand evenly and not too aggressively to avoid damaging the underlying surface.
- Priming: Priming is a critical step when painting over a glossy surface. A high-quality primer will help the new paint adhere better and provide a more uniform appearance. It's essential to choose a primer that is compatible with both the old high gloss paint and the new semi-gloss paint you intend to apply.

Step 2: Choosing the Right Paint
When selecting the paint for your project, consider the following:

- Compatibility: Ensure that the semi-gloss paint you choose is compatible with the high gloss paint underneath. As the reference suggests, latex-based paints like Behr Ultra will not adhere well to oil-based paints without proper preparation.
- Coverage: Semi-gloss paints can vary in opacity and coverage. Choose a paint that offers good coverage to ensure that the underlying glossy finish does not show through.

Step 3: Application
Once the surface is prepared and the paint is selected, you can proceed with the application:

- Applying the Primer: Apply the primer as per the manufacturer's instructions, usually with a brush or roller. Allow it to dry completely before moving on to the paint application.
- Painting: Apply the semi-gloss paint in even strokes, using a high-quality brush or roller. It's often recommended to apply at least two coats for optimal coverage and durability.

Step 4: Finishing Touches
After the paint has dried, you may want to add some finishing touches:

- Inspection: Check for any areas that may need touch-ups or additional coats.
- Cleaning: Clean up any paint spills or marks promptly to maintain the appearance of your newly painted surface.

In conclusion, painting over a high gloss with a semi-gloss is a process that requires careful consideration of surface preparation, paint compatibility, and application techniques. By following these steps, you can achieve a professional-looking finish that will enhance the appearance and durability of your painted surface.

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Behr Ultra is latex based, therefore will not adhere to oil based paint. Also, like PatInPaint mentioned above you will also have to do this if you are painting over is a semi-gloss or high-gloss finish. The best thing for you to do next is to sand the wall with an 80 grit sand paper, prime and then apply the paint.May 3, 2011read more >>