Drywall Mudding Over Paint in 7 Steps

A worker drywall mudding with a trowel.
  • 2-5 hours
  • Beginner
  • 30-70
What You'll Need
Trisodium phosphate
Safety goggles
Safety gloves
Face mask
Paint scraper
Clean, dry rag, or paintbrush
Paintbrush or roller
Drywall primer
Drywall mud
Drywall blade
Sandpaper
Spackling-compound gun (optional)
Trowel
Paint
What You'll Need
Trisodium phosphate
Safety goggles
Safety gloves
Face mask
Paint scraper
Clean, dry rag, or paintbrush
Paintbrush or roller
Drywall primer
Drywall mud
Drywall blade
Sandpaper
Spackling-compound gun (optional)
Trowel
Paint

If you have uneven walls, often due to over-scraping to remove old paint, you might be wondering if you can use drywall mud right over the paint to smooth it out. The answer? Yes—as long as you follow the proper steps. Get started with the guide below.

Step 1 - Wash the Walls

First, wash the walls with trisodium phosphate, or TSP, to remove any dirt, grease, or other debris. Cleaning the walls with a strong product such as TSP also etches the wall’s surface to improve mud adhesion.

Warning: Trisodium phosphate is dangerous if not handled correctly. Use caution with TSP and follow all safety instructions as provided on the product. This may include wearing gloves, safety goggles, a face mask, and long sleeves to protect your skin.

Step 2 - Scrape Off Any Loose Drywall

Before continuing, gently scrape off any loose drywall with a paint scraper. With a clean, dry rag or paintbrush, dust off any remaining loose pieces from the wall.

Step 3 - Apply Drywall Primer

Brush or roll on drywall primer to the wall thoroughly. Then, let it dry.

Step 4 - Use Drywall Mud

Use the drywall mud and a drywall blade to fill in any of the “low” areas or divots that were damaged previously, like by earlier paint removal. Smooth the mud and let dry completely.

Step 5 - Sand and Dust Wall

Now, sand the drywall flush to the wall. Then, wash and wipe the walls down again to remove any dust that’s collected.

Step 6 - Apply Final Mud Coat

While you can achieve a smooth look with some patience, it can be difficult to do. To bypass any imperfections, it’s better to rent a spackling-compound gun and shoot the walls with an orange-peel pattern. This pattern will apply small bumps all over the wall, and it will hide any abnormalities.

After you’ve using the spackling-compound gun, let the mud dry and then go over it lightly with a trowel to remove any sharp points. Then, let the mud dry the rest of the way.

Step 7 - Paint Wall

Now, you’re ready to paint your wall any color you’d like.

Drywall Mudding Over Paint FAQ

Can you put drywall mud on top of paint?

Many types of interior paint have a glossy finish. These paints are made to be smooth and often, to have a little sheen to them.

This slick surface makes it difficult for drywall mud to adhere to paint. If you place drywall mud directly on top of paint, the mud will not stick properly and the job will look unfinished.

How do you fix a bad mud job on painted drywall?

To fix a bad mud job, you need to sand it down to get an even surface. If needed, add mud in thin coats to create an even, smooth wall.

Once the wall is re-mudded and sanded, it can be primed and painted.

Will drywall mud stick to oil based paint?

Drywall mud will not stick well to oil-based paint if you apply the mud directly on top of the paint. You will need to wash, sand, and prime the walls before you apply the mud.

How do you prepare painted walls for mud?

Mud won't adhere to paint very well if you simply place the mud right on it. Sand the paint first to create a rougher surface.

Drywall mud will stick much more effectively to the rough surface of the sanded wall.

How can you tell if paint is oil or water-based?

It is difficult to tell if paint is water-based or oil-based using sight alone. The most effective test is to pour little methylated spirits on a clean rag and test this on a small portion of the paint that cannot be easily seen.

If the color comes off easily, this is a water-based paint.