I dug out my wilton jars of coloring to make halloween cookies and found some of them have gotten a bit dried out. Not completely, but they are a bit thicker.

Is there anything I can add to the few of them that have thickened up to thin them out a bit?

Thank you!

Yep! Stir in a little glycerin (available in the Wilton aisle) until it's the consistency you like. However, if the color is chunky, just toss it and replace with new cuz those chunks will wind up in your icing and that is not good!