For this second layer, I am using blue and yellow acrylic paint. I put a generous drop of each on my plastic plate and pick it up with a putty knife again. In this way, I add a fresh layer of color to the postcards, each a bit different.
A couple of these postcards have a darker blue stripe. This is some masking tape I used while printing a quilt - the tape was used as a mask as I printed, and some of the printing got onto the tape. Since it had color and texture - I added it to some of the postcards in the group.