With Kirsty as model, yellow did indeed become the 5th colour in this series – after a brief, but futile, attempt to get a deep blue fabric to work. Only later did I realise that the light I was using, being incandescent, doesn’t put out a lot of blue light. So expecting expecting a strong blue glow from it was a bit optimistic. Yellow did the trick though, and produced a more accurate colour than the previous two images.
One more to complete this series. Probably electric pink. Probably.