any link please ? does this have a button you push to introduce a hardening agent ? the products i have seen that use the button seem to be decent paints, but it seems to be a waste when a guy only needs a spritz or two. i guess using a "preval" type air/spray unit would be a better compromise. are these type sprayers available with a fan spray nozzle now ? i know the original units were using just a regular spray can nozzle.