Zinsser Seal Coat question

[Bay Area Dave]

I finally picked up some dewaxed shellac. In reading the fine print I noticed that there is a caveat about using it with moisture cured urethanes. BUT, I can't tell if they mean it is a problem putting shellac OVER the MCU, or UNDER it. What's the story?

dave

[B a r r y B u r k e J r .]

Test _your_ combination on a decent sized scrap board.

Barry