I agree, Karin WILL know.
It sounds like maybe you're using opaque colours for your flesh tones, which would not be an authentic glaze. "Glaze" by definition must be transparent, and any layers of which would not obscure your underpainting.
Here also is an article that may help.
http://www.artistsmagazine.com/article.asp?id=1833
Alternatively, consider verdaccio.
http://forum.portraitartist.com/show...0&pagenumber=1