Whiteboard
Albert Stallion invented whiteboards while working at Alliance in the 1960s. Alliance (now known as PolyVision) produced enameled steel for architectural cladding, but Stallion noted it could also potentially be used as a writing surface. Stallion later left Alliance to form his own whiteboard production company, MagiBoards.
Sandpaper
The first recorded instance of sandpaper was in 1st-century China when crushed shells, seeds, and sand were bonded to parchment using natural gum. Shark skin (placoid scales) has also been used as an abrasive and the rough scales of the living fossil, Coelacanth are used for the same purpose by the natives of Comoros. Boiled and dried, the rough horsetail plant is used in Japan as a traditional polishing material, finer than sandpaper. Glass paper was manufactured in London in 1833 by John Oakey, whose company had developed new adhesive techniques and processes, enabling mass production. Glass frit has sharp-edged particles and cuts well whereas sand grains are smoothed down and do not work well as an abrasive. Cheap sandpaper was often passed off as glass paper; Stalker and Parker cautioned against it in "A Treatise of Japaning and Varnishing" published in 1688. In 1921, 3M invented a sandpaper with silicon carbide grit and a waterproof adhesive and backing, known as "Wet and dry". This allowed use with water, which would serve as a lubricant to carry away particles that would otherwise clog the grit. Its first application was in automotive paint refinishing.