Is there any special way to paint popcorn ceilings? Am I correct to use a 3/4 nap roller or so and go to town. Also, there were some areas that I had to touch up with compound, can I use that spray texture (in a can) to touch up where I compounded? Never used it before, anyone?

Just wondering if anyone has ever used this type of paint. I got this from a paint store and was advised it was one of the best brands but more used by industrial companies than for homeowners (but better than CIL or BEHR). Anyone know? Also, the paint store is about an hour away. One of the colors we got ended up being a horrible colour on the wall. We called around to paint stores that are in our area and wanted to know if we could get the paint tinted a darker colour but they all advised they couldn't do this because of painting codes or something like that. Can a store only help with re-tinting of paint if they actually sell that product?