Lab Finishing is a Mercury term. They call their props "Lab Finished". Blueprinting on the other hand implies that the prop will be "worked" and adjusted to certain specifications, just as one would work off of a blueprint, if you will, creating a propeller that is to the highest of tolerance and specifically adjusted to one's boat, motor and drive set-up. Additionally the propeller is adjusted to you, the driver/ throttleman to achieve the goals you have set forth. In other words not just thinned and sharpened but built for your specific application.
Julie