Example of Optical Grisaille process

Here follows a step by step instruction on the optical grisaille underpainting process

1. Choose your reference material – best if it is your own photograph. If using someone elses photograph, seek unambiguous permission to use it if you intend to release the art in the public domain. A lightweight paper black and white print at the size you wish to paint it.

2. Cover the back of the printout with vine charcoal

3. Affix the printout, charcoal face down with masking tape in the position on the canvas you wish to print down the cartoon of the image.

4. Use a sharp HB pencil to draw over the outlines and major features of the form. Use enough pressure to print down a clear unambiguous line to help guide your painting. You are creating what is called the cartoon.

5. Check you have an amount of information printed down that you feel you can handle the more intricate and challenging parts of the form.

6. Use a PITT artists pen by Faber-Castel or india ink by Sennellier with a liner brush to make your charcoal lines perminent. This is called inking in. Be careful to stay true to your lines to not introduce copying errors.

7. Allow your ink lines to dry (minimum 10 minutes). Then mix yourself the imprimatura. Imprimatura is the first stain of paint on the canvas. If your picture is intended to be light and high-key, make your imprimatura light mid-tone. If your picture is going to be deep and dark (e.g Carravaggio style) make your imprimatura dark. You can use oil or acrylic with a flat glazing or varnish brush. See the video in this section how to do imprimatura.

8. Allow imprimatura to dry. Acrylic will take an hour. Oil may take days. Then use white paint – it can be titanium white oil, or titanium white casein or titanium white egg tempera (or, even acrylic if you are happy with acrylic) to softly blend the highlight regions by paying very special attention to the highlights in your reference material. Think of your imprimatura as a mid-tone. There will be a value of the imprimatura that corresponds to a value in your reference photo.

9. It can take several sessions to develop the subtlety. It will look raw at first but do not be disheartened. Also consider the value of your background – is the figure standing against dark or light? Adjust the background value accordingly. This is called the block-in.

10. This stage can be worked on continually until one is satisfied with the effect.

Important : sometimes you will need to use a dark pigment to indicate darks. It is best to make this dark shade a deeper value of the color used for the imprimatura. So if you use a burgundy red for the imprimatura, mix a little tiny amount of black into some burgundy shade paint to describe the deeper values. You may also need to make corrections to where the whites have gone beyond where they are meant to go. Use the same shade as the imprimatura to make these edits.