A system and method for determining when an emulsion or screen is properly cared including a light sensor located on an opposing side of the screen or emulsion from an LED light source operating in at least one wavelength in the ultraviolet range and a sensor monitor that that receives signals from the light sensor and determines the amount of light passing through the emulsion. When the amount of light passing through the emulsion reaches a minimum or approximates zero the sensor monitor may optionally deactivate the LED light source.