Simple DIY: How to Tint Bottles and Jars Microwave 3 tbls of water for 30 secs,add a lot of gel food color and mix until dissolved FULLY. add 1/2 cup of modpodge to the blended food coloring. mix REALLY well. At this point, you can add more color for a more vibrant color. If there are any air bubbles wait for them to subside before use. gel food color tubes work BEST. Coat inside of glass. set oven to 170 degrees, on bottom rack for 20+ minutes, until dry—transparent.