Glaze Layer Calculator — Cumulative Opacity & Depth

A glaze is a thin, transparent or semi-transparent layer of paint applied over a dry underlayer. Light passes through the glaze, hits the layer below, and reflects back through the glaze — creating a luminous, jewel-like depth that cannot be achieved with opaque paint.

Old Master oil paintings typically used 3 to 15 or more glaze layers, built over weeks or months. The dead colour (grisaille) underpainting was overlaid with successive transparent colour glazes. The final surface could be 10–20 thin layers deep.

A white ground reflects maximum light back through the glazes. Each photon passes through the glaze layers twice — once going in and once returning — doubling the colour-modifying effect. Dark grounds absorb light rather than reflecting it, producing rich but less luminous results.

A glaze is a transparent dark colour applied over a lighter layer. A scumble is an opaque or semi-opaque light colour applied over a darker layer. Both build optical depth but through opposite mechanisms. This calculator handles both: low opacity values are glazes, higher values approximate scumbling.

Mix a small amount of paint into a clear medium and brush it across a strip of black and white card. The opacity is how much the underlying card shows through. Many pigments are naturally transparent (e.g. alizarin crimson, phthalo blue) while others are opaque (titanium white, cadmium yellow).