To create a glaze using water-soluble oils, use a medium like Winsor and Newton’s Artisan Painting Medium, or water-mixable linseed oil. Either of these will make the paint thin enough to achieve a veil-like glaze of color while keeping the paint film tough and risilient. Using too much water to dilute the paint creates a chalky, unstable layer in your painting. Add the medium to the paint on your palette and mix it well with a palette knife before loading your brush.
Your semitransparent glazes must be rich in medium so they maintain the flexibility of the paint film. Using a lean mix over a dried layer could result in cracking of the applied glazed later. Colors that work well as glazes are the light sienna earth colors and transparent colors like Sap Green, Alizarin Crimson and the Pthalo Greens and Blues. Try adding Zinc White to make them semitransparent or Titanium White to create a more opaque, misty veil-like effect.
Heather Galloway is associate paintings conservator at the Intermuseum Laboratory in Oberlin, Ohio.