Getting your coloured pencils to pop on a black background

Full o' Beans
9x12 inches
Coloured pencil, Gouache and white ink on Black Mat Board

I have spent the last couple of weeks redoing this piece over and over. I love working on a black background, but get a bit frustrated with the way some of the coloured pencil colours, particularly the reds, lose their vibrance when working on a black background. I decided to underpaint with a white medium. Underpainting with white coloured pencil is quite ineffective and really doesn't add to the vibrancy of colours added in subsequent layers. So I experimented with white acrylic, Gouache, gesso, Colourfix primer and white watercolour. None of them gave me 100% satisfactory results. The jellybeans needed to look smooth and glossy and some of the more textured primers such as the gesso and colourfix made it hard to achieve that smoothness. The pencil didn't apply as well as I wanted over the acrylic or Gouache either. I have dabbled with the Golden Drawing ground, but find it a little too slick for coloured pencils and some of the vibrancy of colour is lost. So, I tried diluting the Gouache with the Drawing ground. The chalkiness of the Gouache was reduced with the slickness of the ground and vice versa. I still wouldn't say that this is the perfect solution, but it was the best of all the options I tried. Back to the drawing board to find that elusive magic formula!!! :)