Just signed up today because I am having this issue where my teal icing loses its blue and goes mint green. This also happens with purple, the blue fades and I'm left with a red purple icing instead of a true purple. 

So I had sky blue wilton gel and lemon yellow, which I used to make teal. Iced the cake, decorating now. And my cake after a few hours is mint green - not the teal I started with. I just ran out and bought straight teal gel and lo! definitely does not match the teal-turned-mint of my cake. 

How do I fix this? Will the teal gel cure into a mint also? Or do I just need to add a bit of yellow to make it match the now-mint cake? 

How long did you let your icing sit before using it? I make my icing 3 days in advance to give it time to rest. I've noticed with Wilton colors, they are notorious for fading. Americolor is a good line, and they make a true teal. I would add the yellow and make it match what you have since you don't have time to scrap it. 

Okay, thank you. I've only noticed the blues fading, never warm colors. Maybe I'll get all my blues from Americolor.