Prepare the wall or object to be painted. Sand and prime as needed. Apply a satin or semi-gloss latex paint for the base coat that shows through the cracks. Allow the paint to dry overnight.
With painter's tape, cover any areas where you do not want a crackle finish. Apply the crackle finish to the edges with a brush or roller, and let the crackle medium dry before applying it to the rest of the surface. Once the edges are dry, apply the crackle medium over the rest of the area with a sea sponge or a brush. A sea sponge creates smaller cracks, while a brush makes larger ones going in the direction of the strokes. If the project is small, you can apply the crackle medium all at once.
Once the crackle medium has dried, apply a topcoat to develop the cracks. Working in sections, paint on the topcoat with a brush. The crackling happens almost immediately. Do not go back over an area that has crackled, or you run the risk of removing the cracks. After the topcoat has cured, spray or brush on an acrylic sealer.