How stripes can disguise a sweat mark
Sweat changes how fabric looks. As moisture spreads through a uniform, it can make some areas appear darker than the dry cloth around them. On a plain surface, that difference has little competition: the eye can pick out the irregular patch against a uniform background.
Pinstripes add repeated lines, giving the eye another pattern to follow. A damp patch crossing those lines is visually mixed into the design rather than appearing against an uninterrupted field of color. This is a form of visual camouflage—a change in what stands out, not a change in the sweat itself.
A visual effect, not a practical cure
The stripes do not keep players cooler, wick away moisture, or prevent stains. Up close, a darkened area can still be visible, especially if it is large or strongly contrasts with the uniform. The pattern simply makes the evidence less conspicuous by giving the eye more detail to process.
That distinction matters on a baseball field: pinstripes could soften the appearance of sweat without changing the heat or exertion of a game. They were camouflage for the uniform, not relief from a hot nine innings.
