Deirdre Sullivan-Beeman paints in a modified Old Masters style that was first devised in the 14th century. Mische Technique, meaning "mixed technique," incorporates both oil paint and egg tempera.

She begins by applying an imprimatura layer onto a gesso board. The imprimatura is comprised of 50% raw umber and 50% odorless mineral spirits. On top of the imprimatura, she sketches her composition with additional raw umber.

Egg tempera is then mixed by hand. To start, Deirdre cracks one egg into a jar and blends it with a little walnut oil and damar varnish. She then adds distilled water and shakes well to combine all.

Next, Deirdre adds a teaspoon of the fresh egg tempera to titanium white powder and joins the two together with a pigment grinder. This mixture is what she uses as an indirect grisaille. Grisaille (/ɡrɨˈzaɪ/ or /ɡrɨˈzeɪl/; French: gris [ɡʁizaj] ‘grey’) is a term for painting executed entirely in monochrome, or near-monochrome.

Once the grisaille is finished, Deirdre begins glazing the piece with transparent layers of oil, applying washes of color. Up to 40 layers of glaze may be applied to a painting. This creates a reflection through the grisaille – like the sun shining through a stained glass window.