Surface wear is different from film grain
Film grain spreads tonal variation across the image; scratches and dust leave more distinct marks. This effect creates both pale and dark dust flecks plus fine vertical lines, scaled to the photo dimensions. The pattern is generated mathematically and stays stable when you change strength, making before-and-after comparison easier.
Start with a modest strength on a quiet background where marks can be seen. A heavily detailed image may hide them, while a clean sky can make them dominant. Color adjustment, grain and vignette remain separate studio controls. Light Leak adds a bright edge instead; Grain Overlay generates a separate texture file instead of a finished photo.

