I'm hanging a solid print (paper) green wallpaper. While brushing out air bubbles, I'm noticing white spots showing through the paper. The white spots feel like there are tiny bumps under the paper. There's a layer of oil based primer over a previous wallpaper backing with a wallpaper water-based primer over the entire surface. Is there a brushing technique you can suggest or any other tips to prevent bumps from showing through? Also, the paper seems don't line up squarely even though the first piece is plumb. Are there any suggestions to help with this issue as well?