Seachem Flourish Epoxy
Available in gray or brown
Flourish Epoxy is a malleable clay based on two component resin. With this sticky clay, pieces of hardscape can be glued together extremely firmly. Take a desired amount of clay from the tube. Knead these thoroughly (with gloves), so that the material is mixed well and roll it into a ball. Place the Flourish Epoxy ball where the hardscape meets, wait a moment and within 5 minutes a permanent bond is created.
Use Brown to glue pieces of wood together. Gray is ideal for joining stones. After 24 hours it is completely cured. This can be done both above and below water. Completely safe for fish in the aquarium.
During processing it can cause irritation to the skin. So use gloves. Avoid contact with eyes.