Surface roughness
At the scale that matters, most surfaces are landscapes. Roughness multiplies contact area, hides soil from a flat cloth, and turns wiping into redistribution.
In detail
A surface that feels smooth to a fingertip is rarely smooth at the scale a soil particle occupies. Roughness does three separate things to cleaning and they compound. It increases the true contact area between deposit and substrate, so adhesion rises. It provides mechanical keying — pits and scratches that a soft deposit flows into and sets within. And it shelters soil from anything flat: a cloth spans the peaks and never reaches the valleys, which is why a wiped textured tile looks clean while wet and grey once dry. That is the whole argument for a brush over a cloth on grout, moulded appliance seams, textured shower trays and trainer soles. Roughness is also something cleaning creates. Every abrasive pass leaves a finer version of the same landscape, which is why a surface that has been scoured holds soil faster afterwards than it did before, and why a dulled patch on a bath or a uPVC frame becomes the dirtiest part of it within months. The conservation guidance makes the same point from the material side: highly porous stones entrap dust that is then difficult to remove, and soft stones are easily scratched by improper dusting.
Why
- Label residue is explained by Surface roughness
- Mould is explained by Surface roughness
- Dust is explained by Surface roughness
- Moss and lichen is explained by Surface roughness
- Grout is explained by Surface roughness
- Unglazed ceramic tile is explained by Surface roughness
- Sandstone is explained by Surface roughness
- Travertine is explained by Surface roughness
Sources for this page
Sources
Conserve O Gram 15/2: Dusting Guidelines for Stone Objects and Interior Architectural Features
National Park Service, US Department of the Interior · Government or regulator
Relied on for: That highly porous stones entrap dust that will be difficult to remove, and that soft stones can be easily scratched by improper dusting procedures. (states this directly)
PVC-U Window & Door Systems: Handling, Installation, Maintenance and Care Guide
The VEKA UK Group (VEKA and Halo profile systems), 2014 · Manufacturer documentation
Relied on for: That abrasive cleaners must not be used on uPVC because they damage the surface permanently. (inferred from the source; not stated directly)