Digital BW, The Print

Yume, there are two easy ways to copy a layer to another document. 
One is to drag and drop holding down the shift key.  You need to have
the source document and the target document visble at the same time on
the desktop.  Click on the source doc to make it the active one.  Go
to the layers pallette and click and drag the layer icon onto the
target.  Hold the shift key down and let go of the mouse button. 
Since both docs are the same size it should position in register
centered (holding shift is what centers it). Another way is to go up
to layers in the toolbar or the flyout menu in the layers pallette and
select LAYER - DUPLICATE LAYER. This will bring up a dialog box where
you will see a drop down for "Destination Document".  If you click on
the drop down you will see choices for all the open docs.  Choose
which one you want to target as the destination and it will go there
in perfect registration due to both docs being the same size. You can
also give it a recognizable name such as red, green or blue instead of
the default "layer#".

Mitch talked about varying the opacity of each layer so he must be
copying them to a new document so all three can be altered.  If you
notice after a split channel all 3 docs have one layer called
"background".  You cannot alter the opacity or blending mode of a
background layer.  I've played with this a bit now and here's how I
do it.

Open image and split channels. Zoom these down a bit so you can see
all 3.  Click on one of them and go the the tool bar to "IMAGE -
DUPLICATE IMAGE".  You can name this some thing like "base" at this
time.  A duplicate of your image will appear on the desktop named
"Base". Now go to the tool bar to "EDIT - FILL". In the fill pallette
select a white fill, normal mode at 100% opacity.  You now have a base
image where you can copy the other layers to.  I use the flyout menu
in the layers pallette to "DUPLICATE LAYER" to copy each to my base
image as described above, but you could use the drag and drop method
also. Now you have a 4 layer image where the base is white and the 3
layers with pictorial content can be manipulated as desired.

This is a pretty cool method for gaining a substantial amount of
control in a B&W conversion and I thank Mitch for sharing it.  The
neat (and sometimes frustrating) thing about Photoshop is that there
are so many ways to acheive similar outcomes yet each offers it's own
special little advantages. Without forums like this one most of the
less conspicuous tools available in Photoshop would probably go
unnoticed.  Thanks again to Mitch.

Jeff M.