Starbond® "Knot-filler" Black Medium-Thick is the go-to black CA glue for those with knot problems in their wood. Known for flawless knot and void fills, this rubber-toughened formula flows thick (500–600 cps), stays put, and cures to a deep jet-black finish that elevates every piece. It’s not just a filler—it bonds with impact-resistant strength across wood, rubber, metal, glass, and more. Whether you’re sealing a knot or securing a component, it delivers clean, controlled application with a flexible, crack-proof hold.