Matte gray mousepads are safest for old optical mice.

Yes, the color matters, especially with older red-LED optical sensors. Black surfaces absorb too much light, making the sensor struggle to see movement. Red surfaces—well, the red light blends in, so the sensor gets confused.

Early optical mice (late 90s / early 2000s) worked by taking micro-photos of the surface. Contrast was everything. A dark or similarly-colored surface gave the sensor almost nothing to track. That’s why you always saw those translucent blue or gray mousepads in offices—they were actually designed for this.

If you’re using a vintage mouse, skip the black or red pad. Go with a matte gray or light blue. Or just use a piece of plain paper in a pinch.

Your mouse wants contrast, not fashion.