Gradients in Layer Masks

Hello everyone, I know how to use Layer Masks but this has always stumped me. How do you use the gradient tool repeatedly in a layer mask? If I do one pass looks great, but if I do another the new gradient replaces the first gradient in the layer mask.

What do I need to do to use the gradient tool in layer masks as many times as I want without "erasing" my first gradient?

Thanks.

Ok, I know you can make a selection with the marquee tool then do a new gradient and it will "erase" in the layer mask. Anyway to do a new gradient in a layer mask without having to make a selection first?

Use the solid to transparent Gradient instead of Black to White. It's on the Options Bar.

Or change the tool's opacity mode. Try Multiply. Depending on what you want, also try Darken, Lighten, and Screen. Heck, try 'em all.

Yes, the Gradient set to Black to Transparent works great. Thanks!