I have recently learned about the technique of split-fountain printing (to create a color gradient on printed pieces), and I am just curious as to whether this would be possible on my Chandler & Price press…
Ditto to the two replies above (disengage the finger that rotates the disc) + add transparent base in between the two colors. This helps extend the hue of the original colors and prevents them from mixing too quickly.
On some presses there are little separators that you can add to help prevent the colors from mixing as well — see the attached photo of a split fountain (with transparent base in between colors), on our Heidelberg KS cylinder letterpress.