Re: "Silhouette Luma" layers affecting main timeline and not just pre-comp

[Mike Imam] "
Any idea how to prevent these modes from affecting the main timeline (i.e. I only want them to apply to the layers in my pre-comp)?"

It sounds like you have the "Collapse Transformations" switch enabled on the pre-comp in your main comp. You'll have to disable that if you don't want those layers punching holes in your main composition.

Alternatively, if you need collapse transformations enabled, find another solution other than Silhouette Luma to create alpha from luminance. I like the "Set Matte" effect. You won't be able to use an adjustment layer to apply it, however, as this will still affect the main comp due to collapse transformations. Instead, target the application of Set Matte specifically to those layers you need to matte.

Darby Edelen