I've decided to rag some of my walls. I've decided this may be the best way for me to do a large area without too many problems. Meantime, I have never done this, and cannot understand much of the language used to describe the ragging technique. I tried a small portion with crumpled up plastic bags and it looks good. First, I am applying primer to my walls. What I want to do is apply a light beige color over that and then an even lighter color beige over that, using plastic bags (of which I have plenty) to dab on the lighter colored paint. In this case, is it advisable to rag one entire wall in one session? Because I've seen comments where people say there are 'lines' if they stop and it dries. Do I have to be concerned about this? And is this where glaze comes in so that it takes longer to dry?