Several times a year I create a t-shirt for the Riverton Parks and Recreation Department pro-bono, or exchange for race entries. It is a way to do an experimental project vs. some of the more straight forward assignments things I do all day. I presented a day of using older buildings that are no longer standing and using a modern illustration method with runners in the foreground. It was kind of crazy to stylize the photographs but tracing in Illustrator really helped out.
I also wanted to add an antiqued appearance to the shirt. This is done by bringing in a bit-mapped texture into Photoshop.
To apply the texture, simply create a channel mask in the layer you want to add the texture. The amount of texture can be modified with the "Brightness/Contrast" adjustments within the channel, not the image part of the layer.