Why is my granite still retaining a lot of water after sealing?
If you look at polished granite with a magnifying glass, you'll see the tiny fissure and pock marks that allow moisture from water and other liquids to penetrate into it. Just because it's polished doesn't make it waterproof. One of my customers recently had picked out 3 prefabricated granite slabs but had to leave them in the granite yard for two weeks before I could pick them up. When I bought them, the slabs had darker edges and I was assured from the granite personnel that the darkness came from being exposed to the rain and that it would evaporate.  We went through a hot spell and by the time I picked up the slabs, the moisture had evaporated and the darkness from the moisture was gone. Don't seal your granite until you are sure the existing moisture has evaporated because it's kind of like painting over a dirty wall, sooner or later the coating will fail.  I don't buy my sealer from the big box stores. Go to a reputable tile or granite yard and get the best sealer you can afford and follow the application instructions. Personally, I use a product called "Rock Steel" and have had nothing but success with it.