This white block is a fascinating material called melamine foam.
You may know it as a Magic Eraser thanks to its unique cellular structure which allows it to easily clean surfaces where other methods fail.
On a molecular level, the material is almost as hard as glass, but its open-cell foam structure causes it to behave like super-fine sandpaper. Add water to this fine abrasive and it can work better than chemical cleaners.
But cleaning isn’t the only thing it can do. Melamine foam is a fantastic thermal insulator, sound absorber, is extremely lightweight, fire-resistant, and non-toxic. This makes it ideal for insulating ductwork, bullet trains, and airplanes where sound, temperature, safety, and efficiency are critical.
Our favorite feature of this material is that it is amazingly cheap when purchased in its generic form instead of the branded version in the cleaning aisle.
