Sanding blocks and sponges are tools and materials used for the processing and finishing of surfaces on various materials, including wood, metal, plastic, and others. They possess abrasive properties as well as a special texture and shape that facilitate sanding and provide the necessary smoothness to the surface.

The key characteristics and functions of sanding blocks and sponges include:

1. Variety of Shapes and Sizes: They are available in various shapes, such as squares, rectangles, triangles, etc., which make it easier to work on different areas of a surface.

2. Abrasive Coating: Sanding blocks and sponges have an abrasive coating on one or more sides, which removes irregularities and roughness.

3. Porous Sponge Structure: Sponges typically have a porous structure that ensures even pressure distribution during sanding and can be used with water or oil to soften the abrasive action.

4. Manual Use: They are designed for manual use, providing good control over the sanding process.

5. Various Abrasives: Sanding blocks and sponges can be coated with different types of abrasives, such as aluminum oxide, silicon carbide, and others, depending on the required coarseness and the type of material being processed.

6. Applications in Various Fields: They are used in woodworking, metalworking, the automotive industry, repair and finishing, and other industries.

Sanding blocks and sponges are convenient tools for sanding and finishing surfaces. Their variety of shapes and abrasive coatings make them suitable for various tasks, allowing for smooth and high-quality results.