your opened icing coloring?
Do you have a box on a shelf or do you store them in the refrigerator?
I had a customer ask me this a few days ago. She wasnt sure how to store them after they were opened.
She usually doles out what she needs with a clean toothpick if its in the jar type coloring and tightens the lid and places it on the shelf in her pantry. But she was buying some americolor electric pink and blue and since its a squeeze bottle wondered if the refrigerator is best for al her jars and bottles.
I store mine at room temperature in a box.
I told her I thought room temp was fine as long as she had not double dipped the toothpick in the jar and it had icing on it.
I prefer the squeeze bottles over the jars its less likely to contaminate them with toothpicks.
At the Wilton school we stored them on the counter, no refrigeration needed. They did warn us that double dipping a toothpick could cause it to turn moldy. The biggest problem there was some students would put the wrong lid on the color. For example, I wanted pink color but it was actually peach. Couldn't tell it was the wrong color until I had kneaded it into my fondant. I also prefer the squeeze bottles but sometimes I over squeeze.