I trained years ago on a GTO 46 but been out of it for years. Trying to set up a small shop but having problems developing plates for my Rotaprint SRA4 machine.
I'm exposing aluminium posi plates to UV light for 2 minutes using a professional unit with new bulbs. Longer than this seems to leak around the film though I'm using a vacuum unit. The plates seem to image well, they are green coating to start with turning blue when exposed. I'm using a general clear metasilicate developer solution but I find using a sponge the imaged area soon comes off too! If I just leave it to soak for a while the plate bubbles and yet just a quick wash doesn't seem to take anything off.
What am I doing wrong? As far as I remember I'm doing this right?