Methods and systems for producing coated optical substrates, and photochromic ink formulations therefor

A coating system comprising:

• (a) a photochromic-ink-formulation-application station including microvalve apparatus configured to microvalve droplets of a photochromic-ink-formulation onto a target surface of an optical substrate to form a wet layer on the target surface;
• (b) a drying and/or curing station configured to dry and/or cure, on the target surface, the wet layer to produce a cured coating thereof;
• (c) an optical-substrate transfer apparatus configured to transfer the optical substrate having the wet layer on the target surface thereof from the photochromic-ink-formulation-application station to the drying and/or curing station;
• and
• (d) a treatment station for increasing the surface energy of the target surface before application thereon of the primer;
• and
• (e) a controller configured or programmed to control the microvalving of the droplets of the formulation onto the target surface;
• wherein the microvalving is such that a dimensionless ink coverage ratio (RD1) defined by a ratio of a mean volume of formulation applied per unit of area of the target surface in an edge portion thereof characterized by lying between 90% and 100% of a distance from a centroid of the target surface and a perimeter thereof, is between 0.60 and 0.96 times a mean ratio of a volume of formulation applied per unit of area in a central area characterized by lying between 0% and 10% of a distance from said centroid of the target surface and said perimeter.