Lacquer Paints...

What I do with pastels Ian, is use them as my last weathering technique on all my models. I grind the pastels up to a fine dust and apply by scrubbing it into the nooks and crannies and / or applting a dusting with a fan brush. Once this is complete, so is the model, I never seal the pastels onto the model. I found that sealing them in takes away from the final effect too much.

The mention of lacquer you have been reading about most probably refers to Tester's Dullcoat Lacquer, a common clear-coat flat lacquer used to seal paint jobs and leave a dull finish. While it is true that car modelers sometimes use automotive lacquer paint because of its high luster and ablility to be polished, If you are a tread-head, there is no reason to mess with these highly flammable and highly toxic paints. Metalizing paints, used to simulate natural metal finishes on aircraft, are also commonly lacquers. If you can't find Dullcoat in NZ, any matt vanish varnish will do, providing it can be properly thinned and sprayed without any problems.