In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.[1]
[pinit] I looked on the back of a Magic Eraser package the other day and noticed there werenât any ingredients listed. That seemed very odd to me since just about every cleaning product out there has some kind of ingredient. I did a quick search and found out Magic Erasers are made of a product called melamine foam.
Before we get to how erasers work, though, let's learn a bit about what exactly is on the paper that you're erasing. Although we call the black stuff in pencils âlead, it's not the real metal known as lead. It's actually a mineral called graphite, which is made up of carbon. When you write with a pencil, graphite particles from the pencil rub off and stick to the fibers of the paper you're writing on. While pencils are filled with graphite, erasers are made mostly of rubber, although plastic and vinyl are sometimes used. The rubber is usually combined with sulfur to make it last longer. A softener, such as vegetable oil, is also usually added to make the eraser more flexible.