When leveling a finish with sandpaper and a lubricant, you can get a quick view of where you are in the process by using a plastic spreader to remove the sludge from an area. As long as the finish you applied has a gloss sheen, dips and pores where you haven’t sanded enough show up well.
The plastic-spreader trick is a lot quicker than washing off all the sludge with a rag and mineral spirits, or a rag and water, and you don’t have to let the solvent or water dry to see what’s happening. The shiny areas show up well.
