The TAZ 6 does automatic leveling by probing the corners of the bed. You'll have to change the Z offset through the printer's menu. If you are adding a 3 mm plate, then you would add 3 mm to the Z offset.
swclark: I am most interested to see how long can the object remains on the glass before it loses adhesion. Also do you wait for the hairspray to dry before heating up the plate and/or start printing? erniehatt: Just thought of a problem. I apply the glue stick directly onto the glass just before heating it up. If I put too much glue onto the glass plate (i.e. layer of glue on glass too thick), will it cause the object to lose adhesion after prolonged printing? prolonged printing is very important for me because I have a 40cm x 40cm heated bed, and when I print large object, it will be easily an overnight, or even multiple-day job.
Mark, I tried the glue stick and had very little luck with it.
I normally thin the PvA about 60% water to 40% PVA, but these are experimental. I apply it as the bed is heating, I am trying some other ways that I will put on the forum if they work out.