A method for marking mixing nozzles should be implemented in any plants that run them. Running processes with a mixing nozzle not only raises the peak pressure to fill but also impacts shear on the material and packing pressure drop, and creates locations to trap contamination. They can be a useful tool to resolve color mixing issues but are really a “Band-Aid” to try to improve poor melt quality from an inferior screw.Be aware of nozzle lengths as well. If a 6-in nozzle is all that is required, a 12-in nozzle should not be used as a “universal” nozzle. Longer nozzles create more restriction and potential pressure drop. It is also more difficult to maintain good thermal control on longer nozzles.