What shape is recommended for wipes in sample collection?

• A. S-shaped wipes
• B. Circular wipes
• C. Rectangular wipes
• D. Triangular wipes

Answer: (A)

Covering the sampling area with a serpentine (S-shaped) wipe pattern ensures full, uniform contact with the surface. This motion creates overlapping strokes as you move across the area, so you don’t miss spots in corners or along edges and you avoid gaps that could bias the sample. The goal in wipe sampling is to obtain a representative collection of any dust present, and an S-shaped pattern provides a repeatable, continuous path that standardizes how the surface is covered.

Other shapes of movement—circular, straight-line, or triangular—don’t inherently guarantee the same even coverage. Circular motion can leave gaps between passes; straight or rectangular patterns may miss corners or edges or result in uneven pressure; triangular motions can overshoot or skip sections. The key idea is a single, overlapping path that uniformly traverses the entire defined area, which an S-shaped pattern accomplishes.