Quick Tip: River Rock Reaction | Kilnforming

Quick Tip: River Rock Reaction


Make a part sheet with stony effects— then cut it up to create projects!

the amazingly realistic rick rock reaction imparts the appearance of a bumpy texture

Reactivity is key to achieving the pebbly look of the part sheet featured here. Under kiln heat, sulfur-bearing frits react with lead-bearing powder to create a rocks-in-a-streambed effect.

To make this part sheet, start with a base of 3 mm Clear (001101-0030-F) or Tekta Clear (001100-0380-F) sheet glass. Mix together French Vanilla frits (000137-0001, -0002, -0003) in equal portions by volume—enough to cover your base sheet with a layer that’s one frit thick. Weigh the frits and pour them into a clean container with a lid. Using a spray bottle, spritz the frit grains with enough water to dampen them, then put the lid on the container and shake to distribute the moisture. Next, weigh out Sunset Coral powder (001305-0008) equaling 5% of the weight of your frits. Sprinkle the powder over the wet frits, replace the container lid, and shake. As the powder is distributed, it will stick to the wet frits. When the mix is relatively uniform, pour all of it onto your base glass and spread it out evenly. For firing we recommend the following schedule, which facilitates melting the stiff opalescent frits into the thin base, as well as proper annealing.

Rate Temperature Hold
400°F (222°C)        1000°F (538°C)       :30
600°F (333°C) 1500°F (816°C) :10
AFAP 900°F (482°C) 2:00
100°F (56°C) 700°F (371°C) :00
AFAP 70°F (21°C) :00

Once the part sheet has cooled, flip it over so the Clear is on top. Then you’re ready to cut the sheet and use it in projects like the French Vanilla platter shown below.

a finished slump glass plate with the river rock reaction

When designing your part sheet, consider making it larger than needed by about an inch all the way around. Firing the unknown volume of frit onto the 3 mm base will likely distort the sheet's edges, and you may need to trim them if you want straight sides.

Downloadable PDF
Quick Tip: River Rock Reaction

Helpful Resources

Video lesson: Color Reactions and Special Effects
Reactive Potential of Bullseye Glasses
Quick Tip: A Riot of Effects