DO NOT heat gel in the microwave. Remember that gel is made of mineral oil, and oil is flammable. To increase the bubbles in gel, let it set in a cool place, such as the refrigerator. If you want your candle to maintain its bubbles, do not place in the bathroom. The warm steam will cause it to lose bubbles.
Dyes are available in powder, blocks, chips, flakes, and liquid.
To maintain the clearest level of gel, liquid is best. However, using blocks or flakes can achieve a clear gel candle too. Be very careful of the amount of blocks or flakes you use. When desiring just a light color, and using a liquid dye, use a toothpick for coloring. An entire drop can create a very deep color in gel, depending upon the amount of gel you are coloring.