Color Reactions Tip Sheet

Understanding how color reactions work and which colors will react to one another can create intriguing design opportunities for your kilnformed glass. This tip sheet shows which colors have reactive potential and what that reaction may look like after being fired in a kiln.

Color reactions occur when two glasses with specific chemistries interact to form a third color. The three main groups of glass chemistry for color reactions are glasses that contain copper, sulfur, or lead. The good news is that Wissmach Glass does not make lead-based glass styles in our fusible 96 catalog. So, we only have to pay attention to those bearing copper and sulfur. When combining a copper-bearing glass with a sulfur-bearing glass during kilnforming, a color reaction may occur where they are in contact. This reaction often presents as a dark line where the two colors meet. Notice the dark lines in the photograph where the oyster pearl glass (96-09) and the reactive blue (96-14) come in contact. These lines also occur where the gold tone (96-10) contacts the reactive blue. Reactive Blue is a copper-bearing glass. Oyster Pearl and Gold Tone are sulfur-bearing glasses. The lines you see in the photograph are the visual formation of copper sulfide.

Below is a list of all the Wissmach glass styles that contain copper or sulfur. It’s important to note that the reactive potential of individual glass styles varies based on how much reactive material the color contains. Some combinations of glass styles may not even result in a visual reaction. Testing color combinations is recommended.

If you feel so inclined, share photos of your creations with us. You can post to your own page and tag @wissmach_glass on Instagram or @wissmachglass on Facebook. Or post in our Friends of Wissmach Glass Facebook Group.

-Drew Kail, Wissmach Kiln Consultant