The shine comes from a smoother surface
Kaolin is a fine, pale clay used in the coating applied to many glossy magazine papers. The clay does not make a page shiny by itself. Instead, tiny mineral particles help fill the paper’s pores and soften the bumps and fibers that would otherwise leave its surface rough.
A smoother page changes how light and ink behave
On rough paper, light scatters in many directions, making the surface look more matte. A smoother coated surface reflects light more evenly, producing the familiar gloss. It also gives printing ink a more uniform place to sit, so photographs and fine details can appear sharper and colors more vivid than they would on uncoated stock.
The coating is made by combining the clay with materials that help it stick to the paper, then applying it as a thin layer. Gloss depends on the finished surface and the paper-making process, not simply on adding clay: the coating must be spread evenly and smoothed. That thin mineral layer is why a magazine page can look polished while still being made from paper.
