You put so much effort into painting your walls or household furniture, only to find out the paint isn’t sticking to the surface. Why does this happen and how to fix it?
The main reason why this is happening is because of improper surface preparation. Before you apply paint, the surface must be unsealed, cleaned, sanded, and primed. If you skip any of these steps, the coating will not stick well.
Also, moisture problems, humid or cold weather, and using the wrong type of paint can cause it not to stick. To improve adhesion, you should prep and prime the surface to give the paint an undercoat to stick to.
Why Won’t Paint Stick?
Here are common reasons why this happens and how to fix it:
1. Dirty Surface
Many homeowners apply paint directly on stained walls and furniture, believing that the coat will mask the stains when dry – This is false.
When you paint directly on a filthy surface, the coat will not stick because dust, dirt, and greasy deposits form a loose barrier that prevents good adhesion.
Instead of sticking to the wall or furniture, the coat will air-dry in place and gradually peel off after some time.
To fix this, you must scrape the surface (using a scraper) to remove any sticky residue. Next, you must clean it using warm water, a microfiber rag, and dish soap.
You can also use a liquid cleaner or stain remover to clean it, but ensure the product isn’t oil-based. After cleaning, leave the surface to dry for a few hours before repainting.
2. Sealed Surface
If the surface or furniture is sealed, the paint won’t stick over it. That’s because sealers (or sealants) are waterproof coatings that protect the surface and prevent liquids (including paint) to penetrate it. Since paint can’t penetrate, it won’t stick.
Here’s how to know if the surface is sealed:
- Glossy surface: If the surface is shiny or reflective, it has been sealed. Sealer coats often have a glossy appearance.
- Sprinkle water over the finish: If the water is absorbed, it has no sealer. If the water beads on the surface, there is a waterproof sealer coat.
- Scrape it: If you can see a glossy film on the scraper, it means there is a sealer in place.
The only way to fix this is to remove the sealer coating first. There are two main methods to remove the sealer – sand it off or strip it with a paint stripper.
Sanding is advised for small surfaces, such as your kitchen cabinets, shelves, and baseboard trims. For larger surfaces, such as walls and floors, use a paint stripper.
To sand off the sealer coating, use medium-grit sandpaper (60-80 grit works fine). To use it, use the abrasive side of the sandpaper to scrub the surface repeatedly until the sealer comes off and you can reach the wood underneath. When you start seeing wood shaving, stop sanding because this means the sealer coat is off.
To strip the sealer coat, use a commercial paint stripper. Stay away from caustic and chemical-based stripers as these can discolor your surface. Use a water-based or bio-grade paint stripper for this. For this guide, we recommend using Citristrip.
To use it, apply the stripping compound directly on the sealed surface in a generous amount and leave it for 30 minutes. The stripping compound will absorb the sealer coat. After 30 minutes, scrape both the sealer and paint stripper off of the surface using a plastic scraper.
Pro Tip: After stripping the sealer, you should neutralize the surface with white vinegar and warm water mix. Then leave it to dry for a few hours.
3. Wrong Type of Paint
If you are using the wrong type of paint, the coating won’t stick. Homeowners often use leftover paint on other surfaces without checking if it can be used on the intended surface.
If you are using specialty paints, such as masonry, metal, or aluminum paint on household furniture, it will not stick because it’s not designed to be used on wood.
How To Fix
The only way to fix this is to use the right type of paint.
4. Moisture Problems or Humidity
Moisture on the surface will prevent the paint from sticking properly because paint can’t stick to wet surfaces. If you washed the surface, you need to leave it for a few hours to get dry before it can accept paint.
Also, if the surface is affected by spills, a damaged pipe, or exposure to water in any way, the coating won’t stick.
Moisture problems are common in areas of the home that deal with water or steam. This includes your bathroom, kitchen, dining area, and laundry room.
You can also encounter moisture problems when painting in humid conditions. When the weather gets cool, the moisture content in the atmosphere clings to corners and crevices on your surface, and these can prevent the coating from sticking.
The best way to fix this problem is to find where the moisture is coming from and fix it. If you have a damaged or rusty water pipe, replace it. If there is water on the surface, either due to a water spill or rainfall, wait until the surface dries completely.
You can also check the moisture content in the atmosphere using a humidity gauge. If the humidity level is higher than 50%, you should postpone the paint application. You should only paint when the humidity level is between 40 and 50%.
Pro Tip: If the surface is going to be exposed to constant moisture, you should apply a waterproof topcoat when the paint dries fully. A good choice is polyurethane.
5. Poor Paint Mixing
Before you apply paint, manufacturers advise you to mix or thin it, usually with 5%-25% paint thinner (the ratio varies based on the type). The purpose of thinning is to give the coating a nice flow and consistency that makes it dry faster and easier to apply.
If you apply too much thinner, you will cause the coating to become too light and it will not stick. Also, if you mix it too vigorously, you can trap air pockets in it that will cause it to peel off.
Another common mistake is mixing different types of paints. While you may think this will avoid wastage, it’s a very bad idea. Paints have different formulas and ingredients that aren’t always compatible. So, if you mix two types that don’t go together, you’ll end up with poor flow and consistency that will not stick regardless of what you do.
If you already applied too much thinner, the only way to fix it is to increase the paint-to-thinner ratio or apply more paint. This will even out the mixture, making the flow thicker.
If you mixed the paint vigorously, it’s advised to leave it to settle and then try reapplying it.
Pro Tip: You shouldn’t mix different types of paints. If you must do this, you should ensure that both types of paints have the same base and are compatible (water or oil-based). Also, only use a mixer or electric-powered drill to mix it.
Other Tips To Improve Paint Adhesion
1. Use The Recommended Primer
Applying a primer on the surface is always recommended.
Use a water-based primer for water-based paints and an oil-based or enamel primer for oil-based paints. There are some oil-based primers, such as Zinsser shellac-based, that can also be used for latex (or water-based) paints.
You can check the manufacturer’s instructions on the container to know the type of primer you should use. It’s also common to see primer coats designed by the same manufacturer as your paint.
2. Remove Existing Coating
Before applying a new coat, always check for an existing coat or sealer. If the existing finish is oil-based, remove it before applying a new coating because oil-based finishes are glossy and water-resistant. This will make it difficult for the new coat to stick directly.
If the existing finish is latex or water-based, you can leave it because it can be painted over. Also, if the existing finish is wet or chipped, you must remove it and start fresh. Use solvents, a paint stripper, or sandpaper to remove it.
3. Prep Your Environment
Before painting, ensure the environment is paint-friendly. If the humidity level is high, you can use a dehumidifier. You can use a paint tent if the room is dusty. The surface must be wiped and cleaned.
4. Seal the Surface
It’s advised to seal the surface if it’s defective. If you are working on rotted wood or stained walls, apply a sealer undercoat before applying paint. The sealer will seal the defective surface and provide a smooth undercoat.
5. Spray It
Applying paint with a spray gun gives better adhesion because it is applied at high pressure which makes it absorbed by the surface more quickly.
In summary, you’ll encounter paint adhesion problems if the surface isn’t well prepped – Dirt stains, an existing coat, and moisture problems will prevent it from sticking properly.
Also, using the wrong paint or primer coat and applying it in frosty temperatures can lead to adhesion problems on the surface. To fix the problem, you need to find the exact reason causing the improper adhesion and follow the steps discussed in this post on how to fix it.
Experts advise cleaning and prepping the surface properly before applying a coat over it.