Back in May I wrote a blog about my experiment to see if polymer clay was light fast. After that I wondered how the colours would fare directly in the sun. If you remember, I had cut three strips from the same spectrum gradient blend of Fimo Professional “True Colours”. This time I used the strip that had been on my wall in a North facing room as the colours had not changed much (I wanted to preserve the control strip which had been stored in a drawer, and compare to the strip that had been sitting inside on a South facing windowsill). This time I left the piece on a South facing windowsill outside for the summer.

As you can see, this time there is a definite colour change. The strip has faded overall, but the yellow seems particularly affected. The orange and green (when blending with the yellow) have particularly changed while the others have mostly kept their hue but have become paler.
I am a little disappointed that the colours do fade, although the strip is still nice and colourful when not compared to the original colours. I have seen some lovely garden ornaments made from polymer clay and they withstand the elements very well, but it would probably be best to stick to earthy colours when making something intended to go outside. This way a slight shift in hue would not make a big difference. Perhaps there’s a UV protective varnish that can be used to preserve the bright colours?
Since I’ve only tested one brand of polymer clay here: please let me know in the comments if you’ve had any experience with colours changing (or even better – not changing!).