A good way of finding the corresponding clay colours from your chosen palette is to work out a few colour wheels using primary colours blended in steps to arrive at the various secondary and tertiary colours. The values or colours from these wheels can then be mixed with third colours such as white, black, grey, ecru or champagne or gold to produce beautiful, complex tints, tones and shades of the original colours.
Some very good examples of this can be found on Sculpey’s site in their section on colour mixing and Fimo provides some .pdf format charts of recipes for their product here and here. My own experiments are detailed in the coming pages.
Theoretical Colour Wheels
If you have access to a graphics program you can test the theory of colour wheels easily enough. Use your software to make a simple rectangular bar then using the fill or colour tool, set a gradient fill using two primary colours, such as red and yellow. Presto! You now have a bar that shades from solid red to solid yellow. Some softwares will allow you to set the gradient so that it completes the transition in a specific number of steps – if possible, set it to 8, a manageable number. If it doesn’t allow you to easily do this don’t worry, we can eyeball it.
What this bar says is that the colour between the yellow and red, an orange value, should be the equal mix of yellow and red. In clay this would mean an equal amount of red and yellow clay would produce an orange value.
Clay Colour Wheels in Practice
In practice, this is only good as a reference or a jumping off spot. If you’ve ever worked with red and yellow clays, you know that the reds are, as a rule, over-saturated pigments and drown out any colour along side of them. An equal mix of red and yellow clay doesn’t produce a middle value of orange but more likely a very slightly orange-y red.
So what can we do? Well, there are a few solutions. My approach is to dilute the most saturated of the primaries using translucent clays. This is similar to watering down very thick pigments in painting. How much translucent you need to use to make the colours more equal is a matter of experimentation but I’ve found 25%-50% to be a good *starting* point. Most of my experiments are done first with a 25% – 75% ratio of translucent to red or blue clays.