Perhaps it's because the new press is letting me use higher pressure, maybe it has to do with how I'm cleaning the plates at the end of the day. I don't really know, but I do know that now there is dark ink besmirching my light-colored prints after many, many passes through the press.
When I'm at the "production" stage with my work, this won't matter. I'll carve plates to be inked with a specific color. If I ever need to change colors on a plate, I'll just make sure to follow the standard reduction printing order, light to dark. But for now I need more flexibility in how I do my experiments.
So I decided to try a new technique for preparing the plates. Instead of painting on the shellac one thin layer at a time, I built a masking tape dam and flooded the plate with shellac. This should allow the shellac to soak deeper into the wood, filling in the air spaces that are currently filling with ink.
One of the problems with this, though, is that thick shellac dries very slowly. Warmth is the one thing that I've found to help speed it up. You know how we're going to be opening a co-op gallery space here? Well, last year I bought a glass display case from a business across the street when they shut down.
To make a "warm box", I wrapped that case in sleeping bags and put a low-wattage light bulb in one end of it. On the other end I installed the glass shelves to hold my wet plates.
The next thing I'm going to try is running the plates through the press with a heavy layer of transparent ink base under high pressure. That way, if the ink gets squeezed deep into the pores of the wood, it will be a colorless ink that gets trapped. Once it hardens in there, there should be no possibility for dark ink to find its way in, right?