Ask a Pro   
  
I was tryng to post this   inquiry on your blog but could not figure out how to do so. My exterior concrete   porch was covered with a carpet which I removed. I rented a carbide sander which   removed most of the glue but there are still stubborn spots throughout. How can   I best remove those spots? If they remain, what effect will it have on the   stain? Thank you for your assistance.