Since I have not yet taken the plunge (financial or skill-wise) into airbrushing, my weathering get done with chalks and drybrushing. DullCote (so I've heard, and experienced a bit myself) tends to "hide" chalks so that you have to over-weather, and guess how much it will tone down.
I happen to have a spray can of Krylon matte finish which seems to be intended for sealing artwork and projects, which makes me think it might be less likely to mask chalks (it also has the advantage of being low-odour -- I think it's an acrylic). A test spray on some scrap styrene, which I had smeared with scrapings from artist pastels looked OK. But before I squirt this stuff on my nice Atlas GP7, I was wondering if anyone had any experience with it? In particular, whether it works better on chalk weathering.
-- Steve