Golden Sandable Hard Gesso is a 100% acrylic polymer emulsion designed to be sanded to create ultra-smooth and even surfaces on rigid substrates. This product is designed solely for use on inflexible substrates, such as wood, hardboard, or metal panels. If used on absorbent surfaces, such as canvas, cracking can occur. Apply in multiple thin layers, gradually building up to the desired thickness. Single thick layers could crack upon drying. Allow to dry completely before sanding, starting with coarser grit sandpaper before moving to finer grits for final smoothing.