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Clean up your work by painting over mistakes. Wait about a week for the paint to dry completely. Seal the mural with a clear varnish to protect it.

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Step back and take a look at your work. You will probably notice a few spots where the colors didn't blend well, the paint ran, or some other issue. Most mistakes are pretty simple to fix. Let the mural dry, then go over the damaged spots with another layer of paint. Mix new paint as needed to match the color you need to fix. Mixing an exact match is very difficult. Blend the new paint in with the old as much as possible. Paint feels dry to the touch within 24 hours or less, but that doesn't mean its ready for varnishing. Moisture may still be underneath the top layer. As a rule of thumb, wait at least a week. Some artists like to wait as long as 6 weeks to ensure the paint seals correctly. The amount of time you need to wait varies depending on the paint you use and other factors. Thick coatings of paint take longer to dry out. Cold or damp environments also cause paint to dry more slowly. Oil-based paints can take 6 months to a year to dry completely. If the paint feels dry to the touch after about 1 week, put a layer of varnish on it. Cover it with a final varnish after the paint finishes curing. Choose a clear, water-based, non-yellowing paint varnish. Matte or even satin varnishes work best since glossy varnishes look a little too shiny on murals. Mix the varnish with water to turn in into a paint. Then, use a wide paintbrush to coat the entire mural. Add a second coating after the varnish dries within a day to finish your mural. Using a varnish protects the paint from debris and damage. Always use an acrylic varnish for outdoor murals. Make sure the varnish is removable. If it is, you can scrub it off when you need to touch up the paint underneath it.