For the murals in the Ansgar Church we mix small portions of egg tempera paint.
To make the binder, we mix 1 whole egg. While stirring, we slowly add the equal amount of linseed oil. Next, an equal amount of water is added. Little by little, we then add some of the binder to the colour pigment to achieve a good consistency. We leave the paint to rest for min. 24 hours. We can always add more binder if the paint thickens over time, which it usually does.
In this example we mix a yellow paint with the same colour code as the yellow used in the 9th century. It's called Arsen Yellow because it used to contain arsenic. There is, however, NO arsenic in our colour. This pigment is a paste derived from ground pigments in oil, which makes a more durable paint.
We use linseed oil varnish, which is boiled linseed oil with a quick-drying siccative.
We mix our paint in a kitchen and use glass jars with lids because of hygiene and durability.
A mixed paint kan keep up to 2 weeks if stored in a cool place.