Tempera paint is a non-toxic and earth-friendly paint many artists use as a medium. Tempera blends natural pigment powder with oil, water and egg yolk to create a versatile paint. You can use tempera as a watercolour; it gives the effect of an oil paint without the unsafe ingredients. Since tempera does contain raw egg; don't let children use it without supervision.
The main ingredient in tempera paint is egg yolk. Egg yolk binds the colour pigment to create rich and lustrous colour. The best yolk to use comes from fresh eggs. Since grocery-store eggs are often not fresh, consider going to a local co-op or farm to buy your eggs. Grocery-store eggs are fine to use if there is nothing else available. Let the egg reach room temperature before separating the yolk. Crack the egg and release the yolk by making a tiny puncture in the clear sack encasing it. Use the leftover egg whites for a healthy omelette.
Powdered pigment gives your tempera the deep hues you want. Even though the pigment comes in powder form, you can achieve better colour results if you process the pigment a little more. Use a small colander or sifter to sift out larger clumps of pigment. Once you have sifted the pigment, place it in a mortar and use a pestle to grind it down even further. Smaller particles in the powder will cling to the egg better and result in brighter and more even colour.
Water is the filler ingredient. It thins out your mixture and helps the paint dry quicker. Use distilled water for the best results. Tap water might contain minerals or other pollutants that could restructure the tempura. When you add the water to your tempura, begin with only a teaspoon at a time. You don't want to mix in too much water and make the paint runny, but using too little water will result in a paint that won't spread as well on your canvas. Mix in water until you reach the desired consistency. Check the consistency by painting a line on a small piece of cardboard. Check how the paint spreads on the cardboard; it should spread evenly and not be clumpy or runny.
Clove oil is perhaps the most important ingredient in tempera paint because egg yolk can spoil and create an unpleasant odour. Use clove oil to give your paint a nice aroma. The oil will also inhibit the growth of smell-causing bacteria. Use only a drop or two of oil in your tempera.
There are several recipes for tempera. One of the simplest recipes combines nearly equal parts of ingredients. Prepare one yolk and add it to a mixing bowl. Add one tsp of pigment, one tsp of water and two drops of clove oil. Mix with an egg whisk. Paint a line on a piece of cardboard. If your mixture is clumpy, add another teaspoon of water. Continue mixing and testing until you reach the correct consistency.