Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
Adding diazo increases exposure times by at least 25%, maybe that is where the added toughness derives from...or not? We need a chemist for this one.
Post-exposing the screen after developing and drying is not very effective. To improve the resistance 10-15% the post-exposure time needs to be four times the original exposure time. Exposing the screen fully with the primary exposure offers better resistance than under exposing initially, then post-exposing to improve resistance. Post exposure is most often used for long printing runs when water based and/or abrasive inks are used.
Maybe the addition of diazo does not negate the benefits of post exposure... • SBQ emulsion remains light sensitive after development. Post expose squeegee side to sun or lamp on long WB or discharge print runs.