I've heard that there can be issues with purple food coloring; namely, the red and the blue separating.
I am making a princess cake for next weekend, and was going to cover the cake with purple fondant but am quite nervous about this possible issue.
Is there any truth to this problem, and if so, what precautions can I take?
I have used purple fondant before and have never had a problem like that.
Store anything you make with purple or pink away from direct and indirect sunlight. Shoot any light will fade it. Work on things quickly and then store them in a dark place and transport in a box to avoid an unnatural fade.
Sunlight and florescent lights will spead up the fading quickly.
The only icing I haven't had it fade in is royal. Go figure!
The purple pre-colored Satin Ice is wonderful - it does not fade like the Americolor and Wilton gels. I keep black, red, and purple Satin Ice on hand. There have been posts about Chefmaster no-fade purple food color, but I have never tried that brand. The red pigments fade quickly and leave the blue, so it quickly becomes kinda grayish-blue instead of purple.
Be careful with your brand of fondant as well. I have found that the fondant from one of the suppliers I use (their in-house brand) will not go purple no matter how much colouring you add.....it turns blue. I'm all for Satin Ice pre-coloured purple, much easier.
I just airbrushed a cake in purple and it didn't fade, maybe you could try that?????
as others have said.....keep out of all light... !!!
here's your history lesson on why reds fade: http://cakecentral.com/cake-decorating-ftopict-653200-red.html+dye