Inspection

One of the biggest problems most finishers have is they don't inspect the wood surface as they are white wood sanding. Solid wood comes from the shop with mill marks from the planer, wide belt sander and dents and scratches from handling. Veneer panels have gaps in the seams and also suffer from dents, scratches, veneer tape and glue. If these are not completely sanded out before stain or finish it will require sanding the stain or finish back to bare wood and potentially sanding through thin veneers to the substrate.

  I have always used an inspection light of some kind even if it is just sunlight coming through the shop door at a low angle early in the morning. I bought several of these battery powered, rechargeable inspection lights online and they work great. 

  When you find a defect it is important to circle it with a pencil so you know where it is when you go back to sand it out. It is also very important not to just sand in the area of the defect or you will sand a low area that will be visible in the finish. I use a block and feather the area out over most of the panel and then use my inspection light again to assure it has been removed.

Here I have just orbital sanded a walnut veneer panel and am inspecting for any remaining 

defects before block sanding out the 180 orbital sander marks.