Does powder coating cover up imperfections in an object?

No. Coating over an imperfection will simply give the imperfection a nice color and finish but the flaw in the surface will mirror through the finished coating. Scratches in a surface, grind marks, weld splatter, chips, dimples, rough patches, and the like are imperfections that need addressed prior to the coating of a part if you do not want to see them manifested in the finished product. Therefore, it is strongly recommended that you remove any imperfections in the surface to be coated prior to the powder coating process. Applying the coating to a smooth, clean and dry surface is key to achieving a quality finish.  more