I posted a message about this quite a year ago. The problem was that the spray paint from cans seemed to have high pressure that bounced the paint off from the inside of a book case. Recently I had a chance to add another "book case" like small cabinet in my house. This time I fixed the problem that I mentioned in my previous message by spray- painting each component of the cabinet before assembling it together. I needed to keep paint off the areas that I needed to glue by covering those areas with blue tape. This works well and I likely will continue using this approach for any future projects.
The other alternative that someone has suggested previously is to use paint sprayer that I can adjust and lower the pressure. But I don't have such an equipment (always want to have one; but cannot justify the purchase). Therefore, I am still spraying paint from a can.
I post this just in case someone gets into the same problem and wants to know how this should be fixed.
Jay Chan