Brush marks can ruin any painted surface. Brush marks form when a paintbrush rakes across partially dried paint, when the brush is not filled with paint and when poor-quality tools or paint are used. If the surface being painted is not properly prepared with sanding and priming, brush marks from previous paintings can show through the new paint. To avoid brush marks, you must pay attention to your brush as you paint and use high-quality materials and tools.
Sand the surface thoroughly until it is smooth to the touch.
Clean the surface with a tack cloth to remove all the fine dust particles.
Paint the wood with primer, using a paintbrush. Allow the primer to dry for several hours or overnight.
Apply the paint with a paintbrush in long, smooth strokes, following the natural grain of the wood. Load the brush with enough paint to allow the brush to smoothly glide down the wood. If the paint drips and runs under the paintbrush, you have loaded too much paint in the brush. Reload the brush with paint when the brush pulls against the wood instead of gliding. Attempting to paint with a brush that is too dry will leave brush marks on the wood.
Allow the paint to dry and follow with a second coat.
Painting with a foam brush, paint sprayer or roller instead of a paintbrush will also help you avoid brush marks. Use paint with a drying time of 24 hours or more. Drying times should be written on the paint can's label. Running a paintbrush along a surface with partially dried paint leaves brush marks.