Homebrew PCBs

Hello, 
i have made a tests with Bungard solder Mask and direct white
printing over it with UV hardered INK before solder mask hardering.
It works. I have tried it with a 7feet industrial printer. Now
i must check, if modifying a epson printer and using this ink, i can
reproduce the same result. On the industrial machine, i had the 
feeling, that the UV curing is a combination of UV and heat curing
(70-80 degree). Because i have only access to high resolution piezo
printing, i probalby must filter the ink prior using it in order to
not obstruse the head. Do your have a idea, how i can build a 5um
filter ? The industrial machine had a 300 dbi piezo print head.
Further updates are coming as i have resolved this problem.
As note, i have access to the ink as 1 Liter refill tetrapack.

Chris