A couple of months ago we looked at different writing tools. This month we will inspect some of the material that they write on - paper.
When we look at a sheet of paper we see a thing that may be different colors, it may be smooth or rough, but it is fairly solid (unless it gets wet). We can write on it or fold it into a paper airplanes, even wrap up presents in it. In the optical microscope at fairly low magnifications the paper still looks relatively smooth as you can see in the picture on the left above, but there is hint of some texture. In the scanning electron microscope images to the right we can see that the paper is not smooth. It has many fibers running through it, and in the highest magnification image on the right we can see lots of particles lying on the fibers.
When paper is made (perhaps you have made some yourself - it can be done very easily and is great fun) it starts out as lots of tiny fibers. These may come from lots of different sources: wood pulp, plant fibers, cloth and textile remnants, and lots of it now comes from recycled paper. The sort of fibers used, and the mixture of the different types, are two of the ways that can be used to control the characteristics of the paper being made. The two images here are from very soft papers: tissue paper on the left and a quilted paper towel on the right. Compared to the images of writing paper at the top of the page we can see many more fibers. We can also see down between more of the fibers, so there must be more air in the paper. How many other differences can you find?
The writing paper has a coating on it to make the surface smooth so that when you write on it the ink stays where you put it and doesn't run all over the page. Also in the coating are pigments that give the paper its color.
There are various other things that can be applied to the paper surface. On sticky notes there is some glue attached to the surface. The front of the note (on the left below) looks like the image of writing paper at the top of the page. The back where the glue is looks a lot different. The round blobs in the middle image are tacky dots of glue. At 5 times higher magnification on the right you can see where they are attached to the coated paper.
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Last Update: 7/17/97