Have you ever wondered why there are two opacity sliders, Fill and Opacity, in the Layers panel when they seem to do the same thing? Actually, they’re quite different, but you wouldn’t know unless you apply a layer style. Once a layer style is applied, the Opacity works as you might expect; however, the Fill slider only affects the pixels and not the layer style. By changing the Fill, you can create transparent effects such as glass or water.
This tip previously published in Colin Smith’s Photoshop Tips column, in the March, 2019 issue of Photoshop User magazine.