Properties of Materials – Appearance

📚 Key Concepts

🔹 Lustre Property

Lustre is the property of materials to have a shiny, reflective surface.

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Lustrous Materials:

  • Have shiny surfaces
  • Reflect light well
  • Usually metals (iron, copper, aluminum, gold, silver)
  • Examples: jewelry, mirrors, polished metal surfaces

Non-lustrous Materials:

  • Have dull surfaces
  • Do not reflect light well
  • Usually non-metals (wood, paper, rubber, cloth)
  • Examples: wooden furniture, paper, fabric

Important Points:

  • Fresh cut surfaces of metals show maximum lustre
  • Metals can lose lustre due to air and moisture (oxidation)
  • Some non-metallic materials can be made shiny by polishing or coating
  • “All that glitters is not gold” – not all shiny materials are metals

🔹 Texture and Feel

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Materials have different textures:

  • Smooth: Glass, polished wood, plastic
  • Rough: Sandpaper, tree bark, unpolished stone
  • Soft: Cotton, wool, sponge, rubber
  • Hard: Stone, metal, glass, bone

Applications in Daily Life:

  • Smooth materials for surfaces we touch frequently
  • Rough materials for grip (shoe soles, handles)
  • Soft materials for comfort (clothing, bedding)
  • Hard materials for strength and support (construction)

🔹 Color Properties

Materials come in various colors:

  • Natural colors: Brown wood, green leaves, blue sky
  • Artificial colors: Painted surfaces, dyed fabrics, colored plastics

Color Applications:

  • Safety: Red for danger, yellow for caution
  • Aesthetics: Beautiful combinations in art and design
  • Identification: Color coding for wires, pipes, chemicals
  • Psychology: Colors affect mood and behavior