Boundary Selections!

[IamSam]

As both Trevor and myself have stated, this type of painting is similar to airbrush painting but I feel the need to explain some differences of terms.

In airbrushing, for this example, you might use something like masking tape to make a mask. A mask in airbrushing was used primarily to keep any paint from getting on the support where the tape was applied.

Tape....


Paint on tape....


Tape removed....


Masking, while similar, is a bit different in Photoshop. I like to refer to the airbrush style of masking as stencils, stenciling, or templates.

Let's say we have made a template of the masking tape using the Pen Tool set to path. Then we save the path, convert the path to a selection, and fill the selection with black and we call it "Tape Template 1".


We can now turn off or deactivate the "Tape Template 1" and place it in a group.
We can, at any time return to the template and use it to make a selection by Cmd/Cntrl + clicking the templates thumbnail.

Using that selection, we can paint inside the selection...


...or by reversing the selection (note the marching ants on the outer edge) we can paint outside the selection (which technically is still inside the selection..........but let's try to avoid confusion).


We could also use the selection to create a layer mask to accomplish the same thing!

This layer mask......


.....produces this.


And this layer mask...........


.....produces this.


It's all in knowing and understanding the differences in how traditional airbrushing techniques translate to Photoshop.