A properly applied layer of spray paint should be smooth and attractive instead of riddled with small bumps. The bumps occur due to reasons such as improper cleaning of the surface before application or a rushed job. Sometimes the bubbles are simple enough to repair without a lot of work, but other times it's necessary to completely redo the entire paint job to save it.
The reason for bubbles in your paint is contaminants on the surface before you begin the painting process. Cleansing the surface is an important part of ridding yourself of those insidious bubbles. Before you can properly clean the surface, though, you need to identify the problem. Examine the surface to locate deposits of wax or oil. Scrape wax gently from the surface using a paint scraper and wash the surface with detergent. Oily deposits require nothing more than a rinse with gentle detergent. Allow the surface to dry afterward.
When you have sparse bubbling in the paint that is hardly noticeable, you can fix it without doing extensive repairs. Allow the paint to dry thoroughly. Pierce the bubbles with a fine sewing needle. Flatten the deflating bubble with a paint scraper. Pull it lightly across the surface of the surface, pushing the air out of the bubbles and bringing the paint back to the original painted surface. Only attempt this on projects that won't see a lot of wear-and-tear, because it makes the project more prone to peeling. For example, this method can work on a piece of art your hang in your home, but it wouldn't work with a car's paint job.
Projects with extensive bubbling need a complete scrap-and-start-over approach to repair. Consider the surface underneath the paint to determine what grit level of sandpaper you should use. For example, if you are painting a glossy surface that you want to keep looking smooth even after you paint it, choose a grit that is 100 or above. Sand all the paint off the surface. Switch your sandpaper sheet whenever it becomes congested with paint debris and no longer removes paint effectively.
The final step to fixing the bubbling problem is reapplying the paint in a way that will make it smooth. Clean the surface with detergent and degreasing agents. Hold your spray paint bottle about 6-inches away from the surface and move your hand at a steady rate to apply the paint. Read the instructions on the back of the spray bottle to determine how long it must dry. If you apply a second coat too soon, it may cause bubbling just like before.