Drywalling is quite a task. First you put up big pieces, then you put some mud on the seams, then you lay drywall tape over that, then more mud, and finally you sand it all smooth, prime it and paint it.
It gets to be an even bigger task if you skim coat a room.
I got my first taste of sanding a skim-coated room this week while we were sanding Caden's room. I went all around the room, sanding all the rough spots while Michael was at a meeting one night. It took me a couple of hours and I was quite proud of myself when I was finished, thinking I had saved Michael quite a bit of time and work. (Optimally you use an orbital sander with a vacuum attached to control the dust, but I used a sanding block and wore a mask.)
The next day I asked him if he had found many spots that I had missed. Turns out I didn't save him so much work, though he sweetly tried to reassure me that I had!
The problem was that I was working with direct light. When you are doing a skim coat or drywall work of any sort, really, you need indirect light to identify what needs sanded.
It is amazing what direct light can hide on a wall. Putting the light at a 45 degree angle to the surface you are working on makes finding imperfections much easier. We suggest getting a work light on a stand that can easily move around the room. They're not very expensive and they make it so much easier to see!
The two pictures below were taken with a camera on a tripod with the exact same settings with only moving the light. Check out the difference!