Wow...the images that entertains of that church Rauville.
When I grew up in Florida, Frank Lloyd Wright built a college in the town next to me and had students collect urine to paint on for patina/aging. Or, so the story goes. And yes, IF THE URINE IS ACIDIC, it will work slowly over time.
Vinegar works better!
Urine does produce the bluish color but takes a long time. Believe it or not there are two quicker ways that work well. Liquid plant food or ammonia/salt! The final step is important. Once you achieve the color PRESERVE IT!!! Try using a furniture wax with beeswax, clear lacquer spray....