Thicker Paint: Consider using paint that has a thicker consistency, or use a paint additive to increase viscosity without thinning it too much. Apply Multiple Coats: Applying multiple thin coats rather than one thick coat can help achieve better coverage and opacity. Allow each coat to dry before applying the next.
Patchy paint can result if paint has been applied unevenly. Patchy paint can be down to a variation in surface absorption.
Proper Surface Preparation
Preparing the surface properly is key to achieving good coverage. Make sure the surface is clean, smooth, and primed. Sand down any rough spots and fill in any holes or cracks. This will help the paint adhere better and provide a smoother finish.
Make sure the roller is loaded up good, but you shouldn't press too much while rolling (as you said). The ``trick'' is feathering the edges of the first pass (left to right and top to bottom) and then overlapping the next full roller to get good coverage on that area.
Many painters “break in” a roller cover by priming it with water or thinner. In our lab we never prewet a cover before painting. If you choose to, you must spin it out with five or six strong pumps so it is only lightly damp. Then take even more moisture out by blotting the cover with a paper towel.
The problem could be with the paint you are using. It could be defective, old, or a low quality paint that doesn't cover well. Another option is to try priming an inconspicuous spot, let it dry, then paint over it to see if that helps. If so, go back and prime all the walls with a stain blocking primer.
Changing Colours
Sometimes even if you think one coat has done the trick, in bright light the colour below may subtly come through. So again, two coats is an absolute rule. If it's crazy drastic (i.e. you're going from black to white, or eve white to yellow for example) you might need three.
Buy a thickening agent.
You can buy a thickening agent for your paint from a local home improvement store. Most thickening agents for latex paint are made with water-soluble hydroxyethyl cellulose which works well with the latex. Make sure the thickening agent says it works with latex paint.
Wall condition: If your walls are in good condition, you may only need one or two coats of paint to achieve a smooth, even finish. However, if your walls are rough or damaged, you may need to apply additional coats to cover up imperfections.
Understand the Causes of Uneven Paint Application
Before painting, it's essential to clean and sand any rough spots or bumps on the wall. This ensures that the paint adheres uniformly and provides an even finish. Another factor that contributes to uneven paint application is using low-quality brushes or rollers.
Thorough prep work ensures paint adheres optimally for smooth, enduring finish. Fill cracks and holes with spackle, then sand bumps, drips, glossy, or damaged areas to create a uniform surface profile. Clean walls using TSP cleaner then rinse thoroughly.
Pigments, either organic or inorganic, are what give the paint its color and its ability to cover. The level of concentration of pigment in a particular paint also has a direct impact on the durability of the paint's film.
More neutral colors are another choice for hiding imperfections. Stray away from lighter shades, as they can highlight the blemishes. Mid-tone neutrals like: Gray.
The opacity of a paint is the ability to "hide" the surface underneath. Paints that have more hiding capacity are made with a "white" base which contains a larger combination of calcium carbonate and titanium dioxide.
Wait Times Between Paint Coats
Oil-Based Paint - When using oil-based paint, you should wait at least 24 hours before adding a second coat of paint. Water-Based Latex Paint - When using water-based latex paint, you should wait at least 4 hours before adding another coat of paint.
Use high-quality paint. Before starting to paint, and occasionaly during painting, stir the paint well. Always start with a clean, dry substrate. Fix holes and cracks with the appropriate caulk or plaster compound and allow the patches to dry.
If you have various stains, shellac Bonding primer is the ideal choice. It can be used to cover rough surfaces and old varnish as well as metal and ceramic.
This may be due to any of the following factors: Moisture trapped beneath the surface of the paint film. If the paint is applied over a powdery or friable surface. Surface contamination such as dirt, oil, and grease.
The good news is that you can paint old furniture, without sanding, and it comes out beautifully. I've painted about 8 or 9 pieces of furniture, and I've gotten better results with each one.
Not Fully Loading the Roller
The roller needs to be fully loaded with paint to the core, otherwise you'll get air bubbles on your wall, resulting in “paint acne.” To avoid this mistake, roll back and forth on the roller tray until all bubbles are gone and the roller feels heavy.
Dabbing painters tape against the roller cover is an easy way to work free any extra fibers. Once your the cover is lint free you're ready to begin painting.
When you're waiting to apply your second coat, leaving paint on your brush or roller can cause them to dry out and become unusable. Save time washing them out – instead, wrap up your tools in aluminium foil between coats. This will keep the paint on your brush and roller fresh for a long period of time.