Hi,
As I understand it, it is a form of white glue. I got this idea off of this message board. There was the suggestion to use Elmers as a masking agent (that it worked better than commercial liquid masks), and then several forum members suggested that Testors clear parts cement worked even better than Elmers.
The paints I used were Krylon Primer, Painters Touch Gloss White, And Tamiya Insignia White. I'm not sure if any of these were laquer based, but I don't believe so.
I'll try the windex, maybe that'll help.
Thanks!