With the pin register feature you can make multiple exposures from multiple negatives on the same media. For example, to improve contrast of a Pt/Pd print, you can make an exposure, develop and dry the print, then re-coat the paper, place the print and negative back in the printing frame and make another exposure on top of the first with the assurance that both exposures will be perfectly aligned. This feature enables multi-color processes such as gum bichromate with several color separation negatives (typically in the CMYK color space) and even multiple processes such as gum bichromate over cyanotype over platinum. For example, see these outstanding prints by David Aimone.
First, take time to study the details of alternative processes through educational opportunities or by consulting the many excellent resources on the internet including Christopher James’ authoritative volume “The Book of Alternative Photographic Processes“.
1. Create the negative(s) you will use to produce the image and select a medium such as watercolor paper to support your image.
2. Press a Ternes Burton ST-1 stripping tab onto each of the two registration pins located under the back of the printing frame.
3. Slide a negative between the stripping tabs and the glass, emulsion side up, then attach both tabs to the negative with tape. The illustration shows a piece of paper, but you get the idea.
4. For multiple negatives, repeat the process taking care to align the image on each negative with the image on the first negative before attaching the tape. It helps to place the printing frame above a lighted surface for this step. The glass in the printing frame acts as a light table.
5. With one negative attached to the registration pins, attach a new stripping tab to each of the pins and place the paper under the tabs aligned as you like with the negative. Secure the paper to the stripping tabs with tape. You now have a stack of paper and negative(s) that will remain accurately aligned with each other over multiple exposure and processing cycles.
(The following steps assume you have coated the paper with a light sensitive compound and that it is completely dry)
6. Select one negative and attach it to the registration pins, emulsion side up. Attach the coated and dried paper to the registration pins, coated side down.
7. Make sure the two holes on the underside of the back line up with the two registration pins on the frame, close the back and set the springs.
8. Expose, process and dry the print. Repeat steps 6 and 7 as needed.
Note: Ternes Burton ST-1 stripping tabs are available from Blick and other sources.