Before painting, ensure that your glass vase is clean and dry. You can wipe it down with rubbing alcohol to remove any dust or grease that may interfere with the paint adhesion.

Use masking tape to outline sections of your vase where you want to apply different colors. This step will help you create a clear and cohesive rainbow pattern.

With your paintbrush, start applying the acrylic paint to each section of the vase. Use smooth, even strokes to achieve a polished look.

Layer colors to create additional depth and dimension. Allow the paint to dry completely before removing the masking tape.

Once your vase is fully painted and dry, gently spray it with a sealer to protect the paint. Follow the manufacturer's instructions for drying times to ensure the best outcome.