How To Fix Blotchy Spray Paint? (3 Methods)

If you are not experienced enough, you will have a blotchy spray paint finish. What causes it, and how to fix it?

Blotchy spray paint is caused by improper handling and positioning of the spray gun while spray painting. If you keep the nozzle too close to the surface, spend too much time on a spot, or stop while spraying, the surface will appear blotchy when the spray paint dries.

To fix a blotchy spray paint, touch up the areas with more coats of paint, sand the blotchy paint, or remove the spray paint and re-apply it. The right fix depends on the cause and extent of the blotchy spots.

3 Reasons For Blotchy Spray Paint

If you don’t apply spray paint properly, the spray paint will turn blotchy. Improper positioning and handling of the spray gun will also cause a blotchy finish. The blotchy spots on the surface appear because the spray paint coating isn’t even. 

If you spray the same spot for too long, you will over-apply paint. This causes an uneven paint application and a blotchy appearance. Also, if you keep the spray gun nozzle too close to the surface, the paint will bounce off the spot to other parts of the surface, leading to a splotchy appearance. 

Here are other reasons for a blotchy spray paint appearance:

Moisture

Moisture (or water) can cause your spray paint to appear blotchy. If the humidity levels are high, the water (in the atmosphere) will mix and dissolve the paint particles, making the spray paint coating lighter than it is. So, when the spray paint dries, it will develop light or faded spots. 

Also, spray painting a wet surface will make the finish turn blotchy. 

Bad Surface Preparation

The surface must be clean, sanded, and primed before you apply spray paint. Sanding and cleaning the surface will improve the paint adhesion between the surface and spray paint. So, if you don’t prep the surface, the finish will appear blotchy because the surface won’t absorb the spray paint evenly. 

Painting Over An Existing Paint

If you spray paint over a waterproof finish (or sealer), such as polyurethane, it will cause the finish to appear blotchy. That’s because a waterproof coating will repel spray paint. Since the spray paint won’t stick well, some parts would appear darker than others, causing a blotchy appearance.

How To Fix Blotchy Spray Paint?

There are 3 ways to fix blotchy spray paint:

  1. Apply a new spray paint coating.
  2. Sand down the blotched areas (For mild-medium cases).
  3. Remove the spray paint coat (For extreme cases).

Let’s check out these fixes one after the other.

1. Apply a New Spray Paint Coating

Apply a New Spray Paint Coating

To fix blotchy spray paint, touch up or recoat the blotchy areas. This method works when the blotched spots aren’t many. 

To do this, apply more spray paint to the lighter areas so they can blend with the remaining finish. This method is a quick fix and is guaranteed to work.

For this method, you’ll need the following tools and applies:

  • A spray gun
  • The coat of paint that you applied
  • A flashlight
  • Hairdryer
  • Rags
  • A pair of gloves

Here is a step-by-step guide for this method:

  1. Wipe the blotchy paint with a clean rag.
  2. Inspect the blotchy paint and mark out the areas that appear lighter than the rest (the blotchy areas).
  3. Prep the spray paint by following the manufacturer’s instructions.
  4. Use paper (or a clean rag) to cover the dark areas of the surface you don’t want to paint.
  5. Apply a light coat of spray paint over the lighter areas of the surface.
  6. Allow the spray paint to dry. 
  7. Re-apply more spray paint if the finish is still blotchy and let the surface cure (fully dry).

2. Sand Down The Blotched Areas

Sand Down The Blotched Areas

Another way to fix blotchy spray paint is to sand the blotched spots using fine-grit sandpaper. Sanding will fade out the spray paint coating, making the blotches spots appear even with the surface. This method works for mild to medium cases, and only when the spray paint has dried. 

For this method, you’ll need:

  • Fine-grit sandpaper (use 320-grit upwards)
  • A vacuum or duster
  • A pair of gloves
  • Paint (optional)

Here is a step-by-step guide for this method:

  1. Clean the blotched paint after it dries.
  2. Sand the dark areas using fine-grit sandpaper. 
  3. While sanding, vacuum the dust to see if the blotches spots have reduced.
  4. Once the surface is smooth and even, stop sanding.
  5. If needed, re-paint the blotched surface. 

Usually, sanding down the blotchy areas of spray paint fixes the problem. However, there are extreme cases where sanding down the blotchy areas can’t fix the problem. In such cases, the blotchy spray paint is often damp. The damp texture of the blotchy paint makes it impossible to touch up the blotched areas or sand down the wood. When this happens, you must remove and re-apply the spray paint. 

3. Remove The Blotchy Spray Paint

Remove The Blotchy Spray Paint

If you can’t fix the blotchy spray paint by sanding or applying a new coat, you must remove the entire coat and re-apply it.

If most of the spray paint coating is blotchy, the blotchiness isn’t caused by improper paint application. Instead, the blotchiness was caused by spray painting over a damp (or wet) surface. To fix it, you must remove the spray paint, fix the issue (dry the surface), and re-apply the spray paint. 

For this method, you’ll need these tools and supplies:

  • Paint stripper
  • Paint scraper
  • Rags
  • Paintbrushes

Here is a step-by-step guide for this method:

  1. Use a paint scrapper or trowel to scrape off as much blotched paint as possible.
  2. Apply paint stripper over the spray-painted surface, and wait 20 minutes. 
  3. Re-apply the paint stripper for left-over spray paint. 
  4. After removing the spray paint, dry the surface (or fix what was causing the blotchiness).
  5. After you fix the surface, sand and clean it.
  6. Re-apply the spray paint and let it dry. 

Tip: After fixing a blotchy spray paint finish, apply a sealer over it to increase the durability of the coating. You can use wax over spray paint to darken the finish. 

Preventing Blotchy Spray Paint

Here are expert strategies to prevent a blotchy spray paint finish:

  1. Prep The Paint And Paint Sprayer Before Spraying – Always prep and test the spray paint and equipment before using them. If the paint is thick, it won’t flow evenly through the spray nozzle, making the finish blotchy. You must thin the paint before spraying it. Also, you must prep the equipment by priming the spray pump. This allows the paint to come out well without clumps or clogs.
  1. Prep Your Surface – The surface must be clean, smooth, sanded, and primed before spray painting. If the surface is smooth and perfect, the finish will be too.
  1. Don’t Over Apply The Paint – Don’t spray the same spot for too long, as you can overapply paint on certain surface spots. This will lead to a blotchy finish. So, move the spray paint from side to side without stopping, so the surface is covered with one spray.
  1. Use Paint Shields – A paint shield will prevent paint from splashing over unwanted areas. This will prevent a blotchy finish. 
  1. Wait For Each Coat To Dry Before Recoating – The previous coating must dry before re-coating a spray paint coating. You must wait 30-60 minutes before re-coating to avoid a blotchy finish.
  1. Wipe Off Drips And Runs – While spray painting, wipe off paint runs and drips so they don’t form blotchy lines. You must do this immediately before the paint starts to dry.
  1. Touch Up Taped Areas – You must use painter’s tape to demarcate surface areas. After removing the tape from the paint, touch up the tape lines with a light coating of paint. You can use an angeled paintbrush for this. 
  1. Use Filling And Joint Compound – You must fix imperfections on the surface before spray painting. If the surface has holes or cracks in it, fill and seal the holes with a filling compound. For wood surfaces, use wood filler and for concrete surfaces, use concrete paste. If you don’t fill (or seal) these holes, the spray paint will be sucked into these holes and create a blotchy appearance. 
  1. Position The Sprayer Nozzle Properly While Spraying – The spray paint nozzle shouldn’t be closer than 8-inches to the surface. If the spray nozzle is too close, it will cause splashes and a blotchy finish. Also, you must move your arm, not your wrist, while spray painting. Moving your arm side to side ensures an even coat. If you move your wrist, you’ll only be creating an arch which leads to overapplication of paint.
  1. Wipe Spray Paint Errors Immediately – Paint streaks, lines, or splashes must be wiped off the surface before they dry. 

Painting Over Blotchy Spray Paint

You shouldn’t paint over blotchy spray paint without fixing the blotchy spots first. If you paint directly over blotchy spray paint, the blotchy spots on the spray paint can affect your new paint coat.

Before painting over a blotchy paint surface, you should fix the cause of the blotchy appearance, sand the surface, and use paint primer. This ensures your new finish will not be affected.

Final Words

A blotchy spray paint finish happens because of improper surface preparation, high humidity levels, or painting over a wet surface. To fix a blotchy spray paint, apply a lighter coating over the blotchy finish, sand the blotchy areas once the paint dries, or remove and re-apply the spray paint.  

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