Tetrion Flexible Wood Filler is an easy-to-use, ready-mixed filler suitable for interior and exterior use. The filler bonds strongly to wood and leaves a water-resistant, super-smooth finish, which can be stained, varnished or painted. Tetrion Flexible Wood Filler is resistant to shrinking or cracking and is suitable for wood-filling repairs to doors, skirting boards, floor boards, window frames, nail holes, etc.