It sounds counter-intuitive but how you begin a mural starts with a clean cloth. Before you pencil in your drawing, apply painter’s tape or load a paint brush tray, look carefully at the wall. You will want to wipe away the dust, the minor imperfections, the old roller marks, the glossy surfaces, and the bumps or textured spots of the wall so that your interior paint or your acrylic paint can settle evenly onto a flat and smooth surface. You might think you are looking at a mural ready for a mural but you are not. As you are a painter you are working right up to trim and you are paying attention to the corners and to your outlines. You are going to have trouble spots.
Your hand should be the first thing to check the spot where you want to put up your mural. Are there bits of old flakey paint, dust or grease on the spot, or dents in the wall? Is it rough or flat? This will make a big difference in how paint will move over a rough patch. Will it move smoothly and evenly? Or will your paint drag or skip over this bit of old paint or over a spot of dust or over a dent, or be unevenly absorbed? Even a wipe down for dust requires the wall to dry out before your pencil starts sketching. Your mural might look perfect from 10 feet away but you will have an edge problem, and a texture and patch problem up close if your wall is not clean and flat.
If it is a new painting surface, clean, flat, and smooth, you will find that it will be much easier to draw light pencil marks. You will be able to use a level and measure tape with much better results. You will get a better read on whether the mural is too high, or if there is something in the wall that needs to move. Your mural is going to be placed so that there are no awkward places. Your wall should be clean and you will be prepared to work. There might be more to the wall than just painting it. There is the wall where the mural will go.
Different paint looks different on different walls. A matte wall, a gloss wall, a wall that is just painted and a textured wall all react differently. What you might do with painter’s tape or a brush edge, or with acrylic paint will vary from one spot to another. A spot of painted tape is not always a good idea because you get the edge bleed or because you lift loose paint with the tape. If you tape and clean a spot, you will have to wait until it is clean and dry. If you have tape or paint that is going on an area and you don’t want edge bleed or that paint to come loose when the tape is lifted off. You should check a small spot that is hidden like a painted board or on a hidden spot behind an old painting or furniture. If you test the tape there you will know if it is good or bad, or whether you should apply more pressure on that spot. Or wait until the paint is dry enough before removing tape. It can save hours of frustration when it comes time to do an edge of a mural!
If you haven’t done any surface prep you will run into the issues that most often get called painting issues or mistakes. If there is too much dust or too little flatness on the wall to lay down an even base coat, the patchy appearance will have a lot to do with that, or the way your paint is rolling or with your brush or with the base coat. If you don’t smooth the wall out a brush stroke may seem wobbly because of where the texture of the wall is. The brush stroke on the surface will pick up a lot of extra paint if there is a spot that is raised. If your paint is not even and there is a patchy, textured, raised spot it will be hard to do touch-ups. The patchy spot will show more or it might show through in a shine or smear. Even touch-ups will be tough if the spot wasn’t clean or didn’t get the wall painted.
Pick a spot on the wall for a first wall mural that is small so that you can treat it like a dry run. Pick a spot to do your wall preparation, make some light pencil lines to mark the area you want for the mural, or pick a spot to test one color of paint on the wall. Or just take a spot on the wall that you can just paint the color you will be using. It is not just about cleaning the spot. You want to know if the paint spreads evenly, what texture the spot has, if it is going to be flat, or if you will have a texture spot. This is not wasted time at all. It will tell you what the wall is going to allow you to do before you commit to a larger area.
The painting phase is less stressful. The drawing phase goes better. The base coat looks better because you have time to see the edges of the spot better. The first painted part looks like it won’t have any trouble. Even the second or third painted layer. Even the touch-ups look less risky. You just need the time to dry, and patience for layers. You don’t need to think about dust or about loose paint or about the first part of the drawing. You can just work on the design when you know the wall is ready to be a wall. You can worry about the mural instead.