I want to know which color do I must use to have dark royal blue for this weekend. It's for a 90e anniversary and they want the decoration blue but a dark one. Please somebody help me. I know for dark color I must wait around 2 days to have darker

Thank you very much

I'm no expert, but I would try adding just a little touch of black to the royal to make it darker. Are you sure you're trying for royal blue and not navy blue?