As part of my continuing series on images of everyday objects (click here to see a human hair and grains of salt and pepper) observed under high magnification the images in this post are of a piece of paper towel as observed via scanning electron microscopy. When we look at a paper towel with the unaided eye it appears to be a thin solid sheet. However as we can see under higher magnification, as in the first image above at 500x magnification, paper towels are actually composed of strands or threads of paper fibers that are woven and pressed into a matted sheet.
Additionally as we can see in the image above even though paper towels appear to be solid sheets to the human eye they can contain small gaps and holes. In the image below, which is of the same area of the paper towel only now magnified 1500 times, we can see one of these individual strands that has come loose and is now sticking up slightly away from the bulk of the rest of the paper towel.
This is illustrative because what at first looks to the naked eye like a flat solid sheet, is in fact a very porous and rough surface at the micro level. This is common for a lot of everyday materials and surfaces especially fabrics. In fact one of the key reasons paper towel so absorbent is due to its porous and rough surface.