Acrylic is a good choice of paint for rocks as it becomes waterproof once it dries. Approach rock painting from different angles. It can be a fun family project for the kids. You can do more elaborate painting "in the round" on a rock if you're a more experienced painter. Rock painting can be a type of folk art done in traditional methods or just have fun with it. Hobbyists do it to decorate their homes and gardens. More serious crafters can make extra money selling their painted rocks.
Select your rocks carefully. Pick smooth ones with no cracks and rough spots. Collect river and lake rocks if you live by bodies of water. Choose the rocks to fit how you will paint them. Look for rocks that suggest the shapes of frogs, turtles or rabbits if you plan to paint animals. Pick out flat rocks for two-dimensional pictures.
Wash and scrub your rock with soap and water to remove any dirt or grit. Dry the rock out thoroughly. Brush on a base coat of acrylic gesso. Apply it thickly and evenly, filling in any depressions or uneven spots on the rock. Sand down the white base coat of gesso until it's nice and smooth. Allow time for the rock to dry before painting it.
Draw your design with pencil onto the gessoed rock after you've figured out what to paint. Draw whimsical bugs, faces and animals if you're working with kids. Use traditional decorative tole painting designs for your project. Draw family monograms or toads for the garden. Let your imagination run wild. Cover large outdoor rocks with copies of famous paintings to add a touch of class to your yard.
Put on your smock to protect your clothing, as acrylic paint stains won't wash out. Squeeze out only enough acrylic paint onto your palette as you will immediately use. It dries surprisingly fast. Mix your colours and paint them onto the rock using synthetic or hog bristle brushes. Use old or inexpensive brushes, the rocks with soon eat them up.
Block in the larger areas of colour on your rock. Define and separate the colour areas with dark or black lines to give it a cartoonish look. Add the medium toned colours next, followed by the lightest colours. Use your smallest brushes to paint in the final details. Add the finishing touches and accented highlights. Spray several coats of varnish or sealer on the rock if it will be displayed outside.
Fit the design of the painted rock to its shape.
Be careful with large rocks, don't drop them on your toes or smash your fingers between them.