When you apply stain to exterior trim or fencing, etc., you can select from four different application tools: brush, pad, roller, or paint spray gun. Personal preference is most likely to dictate which tool you use, although the size of the job may also affect your choice. You may use more than one tool on the same project. In addition, the manufacturer of the stain product you select may have recommendations on application methods. Consider the options and their pros and cons before starting your project.