Back into the respirator for me… chemicals are not safe! We used Positiv 20, a photosensitve lacquer,, to create a smooth coat of protection. This protection had to be activated with UV light (in our case a UV nail varnish curer) but only in the areas where we wanted pcb tracks to go. Using a standard inkjet printout of our circuit board we were able to activate only the tracks. The inactive laquer was then removed using developing fluid and we were left with an impressivelly accurate trace of our circuitry. The rest of the copper had to be removed so that only the tracks remained conductive, so Ferric Chloride was used to dissolve the metal and leave the lacquer protected areas. Result: DIY etched pcbs!