Identifying a poor substrate for sliding tool marks involves understanding which materials least effectively retain clear, detailed impressions left by a moving tool.

Understanding Sliding Tool Marks and Substrates

Sliding tool marks are formed when a tool moves laterally across a surface. The ability of a surface (substrate) to record these marks depends on its physical properties, such as hardness, density, and structure.

Analysis of Potential Substrates

Metals (Lead, Copper)

• Lead and Copper are relatively soft metals. They can be indented by tools. While they may deform significantly, potentially leading to smearing, they generally possess enough density and homogeneity to retain some impression detail compared to less structured materials.

Metal Painted Surface

• A metal painted surface consists of a relatively soft paint layer over a harder metal base. The paint layer is easily scratched, gouged, or compressed by a sliding tool, making the tool mark readily visible on the surface.

Raw Wood

• Raw wood is an organic, fibrous material. Its structure is heterogeneous and can vary significantly. When a tool slides across raw wood, the impression may be affected by:
  • Fiber tearing or compression
  • Splintering
  • Uneven deformation
• These factors often result in less distinct, smeared, or incomplete marks, making raw wood a poor substrate for capturing clear and reproducible tool mark signatures compared to metals.

Conclusion on Poor Substrate

Based on the analysis, raw wood is considered a poor substrate for sliding tool marks because its fibrous and variable nature makes it difficult to retain clear, detailed impressions.