More light can conceal. The window that makes a matte page easier to read can obscure glossy print, because visibility depends not just on how much light arrives, but on where the paper sends it afterward. Brightness is no guarantee. A readable page needs a difference between its lettering and background.
Matte paper behaves better. Its microscopically uneven surface produces diffuse reflection, distributing incoming light across many directions rather than concentrating a recognizable image of the window toward the reader. The ink stays distinct. Because dark print absorbs more visible light than the surrounding paper, added illumination generally makes both easier to inspect while preserving their contrast, provided the light is not excessive. Gloss plays another game. Its smoother surface produces stronger specular reflection, sending some light along a mirrorlike path in which the angle of reflection equals the angle of incidence, measured from the surface normal.
Glare steals the difference. When that reflected window reaches your eyes, its light can overlay both lettering and background, reducing the contrast that makes words legible even though the page receives plenty of illumination. Geometry offers the remedy. Tilting the page or changing your seat can move the reflected window away from your viewing direction, while a shaded or less concentrated light source can soften the glare. Matte is not magic. It can still become uncomfortable under excessive brightness, but beside the window its scattered reflection usually leaves the words visible, while gloss sometimes offers the reader a bright rectangle where a sentence should be.
