Gum print registration

Instructions to register gum prints. Gum bichromate printing requires multiple pass to get the right density both for black and white and color prints. Here is how.

Writer and photography / Andrea Baldi


A reliable registration system is helpful to get multiple layers of the gum prints that do not show any misalignment in the different passes. For example, when you expose the second layer in a black & white print to add density if the negative is not perfectly aligned with the first layer, the image will show some blur and it will not result sharp as it should be. At the same extent when printing in color if two layers are not properly aligned (e.g. Blue with Green) rather than merging together nicely the two colors it may result in an inconsistent tint that may impact your final print.

In this short article I describe the system I am using that is based on Ternes&Burton registration pins. Registration Pins are very useful and can save time, but they shall be used carefully and visual verification of alignment is always necessary to avoid pitfalls.

“The method I am using requires that both negatives and the media used for printing are aligned upfront using a simple registration board.”

The method I am using requires that both negatives (the method works also for single negative multiple layers prints) and the media used for printing (e.g. usually paper) are aligned upfront using a simple registration board. The alignment amongst the negatives is firstly done by visual registration and then maintained over time by using registration strips that are inserted into registration pins at exposure time. The process is explained in detail below.

Material required for gum print registration

The following material is necessary to perform a good registration:

  1. Negatives with Registration Marks on the 4 corners.

    Figure 1 Registrations Marks
    Figure 1 Registrations Marks
  2. A transparent Registration Board
  3. Registration Pins [SQ7387909 1/4″ x .085].
  4. Assembly Pins [SQ8140825 1/4 x .055) used during exposure.
  5. Registration Strips [SQ3713998] ST1 Stripping Tabs] 2 per negative.

    Figure 2 Registration Board, Pins and Strips
    Figure 2 Registration Board, Pins and Strips
  6. Tape.
  7. Scissors.
  8. Stapler.
  9. A Loupe 10X for visual registration.
  10. A light box or in alternative a glass table with a lamp under it, as visual inspection tool.

Negative Alignment Procedure

The system requires that all negatives used for a print are aligned with each other’s, and this is done by visually aligning them on the transparent Registration Board, taping on the negatives Registration Strips, that would allow precise positioning of the negative during the exposure.

For the negatives alignment just execute the following steps until all your negatives are registered.

  • Lay down on the light table the Registration Board and fix it with tape on the table.
  • Align the first negative with the vertical and horizontal lines of the board to get it centered.
  • Tape the negative on the board and insert 2 Registration Strips into the Registration Pins.

    Figure 3 Registration Board with Reference Negative
    Figure 3 Registration Board with Reference Negative
  • Tape each Registration Strip on the negative.
Figure 4 Registration strips taped on the negative
Figure 4 Registration strips taped on the negative

From now onward, this first negative will be your reference negative during the whole process, unless you are using a single negative for multiple exposures. In this case you can just skip the remaining steps and go to the Paper Registration Procedure.

Figure 5: Reference Negative Fixed on the Registration Board
Figure 5: Reference Negative Fixed on the Registration Board

With the reference negative well taped on the registration board, place the second negative on top of the reference negative and perform the visual registration of the two by using the registration marks on the corners of the negatives, assisted by the loupe.

Figure 6 Negative to be registered on top of the Reference Negative
Figure 6 Negative to be registered on top of the Reference Negative

Use the loupe to verify that the current negative is perfectly aligned with the reference negative. Check carefully the registration marks on the four corners.

Figure 7: Registration marks alignment
Figure 7: Registration marks alignment

When done, fix the negative with the tape on the board to ensure that it will not move.
Insert 2 Registration Strips on the Registration Pins and tape them to the current negative.
Visually verify that the alignment of the two negatives is perfect.
Remove the current negative and repeat all the steps to align for the remaining negatives.
Finally, when you have registered all the negatives, verify the precision of the registration by layering them on top of each other as a single stack. With the support of the loupe, you can easily verify the perfect alignment.

Paper Registration Procedure

The paper registration procedure concludes the process and allows at the end to start coating the paper and exposing your negatives with accurate registrations for your print. To be noted that it is very important that the paper to be registered has been pre-shrunk (e.g. by 3 baths before being sized and used) to minimize the shrinking that inevitably occurs after few developing/drying phases.
There are few books and articles addressing paper pre-shrinking; just remember that this is key for an accurate print registration.
Insert the reference negative on the registration board.
Lay down the paper to be used for your print on the Registration Board on top of the reference negative with the side to be printed “face down”.
Align the paper with the vertical and horizontal lines of the board to get it centered with the negative.

Figure 8 Paper aligned on the Registration Board
Figure 8 Paper aligned on the Registration Board

Insert 2 new Registration Strips into the Registration Pins and tape them on the back-side of the paper.

Figure 9 Registration Strips into the Registration Pins
Figure 9 Registration Strips into the Registration Pins
Figure 10 Taping the Registration Strips to the back-side of the paper
Figure 10 Taping the Registration Strips to the back-side of the paper

Staple the Registration Strips to the paper to fix them. This ensures that the Registration Strips will not detach from the paper when immersing into the water during development.

Figure 11: Stapling Registration Strips to the paper
Figure 11: Stapling Registration Strips to the paper

Exposure and Registration Procedure

Before the exposure, the negative and the paper shall be registered. This is done with the support of 2 Assembly Pins. Assemble Pins are really tiny and fit very well in any exposure frame ensuring registration between the paper and the negative, but I recommend removing them before exposing them to keep negative and paper well pressed together.
Take 2 assembly pins, the negative used for the current layer, and the paper to be exposed.
Insert the 2 pins into the Registration Strips attached to the paper and then into the Registration Strips taped to the negative.

Figure 12: Assembly Pins Used to expose
Figure 12: Assembly Pins Used to expose
Figure 13: Assembly Pins into the paper Registration Strips
Figure 13: Assembly Pins into the paper Registration Strips
Figure 14: Assembly Pins into the paper and negative Registration Strips
Figure 14: Assembly Pins into the paper and negative Registration Strips

You get a “sandwich” ready to be placed in the exposure frame. Please note that after the first exposure, it is important to check the alignment of the print and the negative with a loupe. Minor adjustments might be required to keep a perfect registration.
Finally, insert your “sandwich” in the exposure frame and block it on one side.

Figure 15: The Negative/Paper “sandwich” is inserted in the exposure Frame and blocked
Figure 15: The Negative/Paper “sandwich” is inserted in the exposure Frame and blocked

The 2 Assembly Pins can be removed once the second half of the frame closed.

Figure 16: The Negative/Paper “sandwich” is blocked in the exposure frame and the Assembly pins removed
Figure 16: The Negative/Paper “sandwich” is blocked in the exposure frame and the Assembly pins removed
Figure 17: Front view of the exposure frame with The Negative/Paper “sandwich”
Figure 17: Front view of the exposure frame with The Negative/Paper “sandwich”

You are ready to expose.

Figure18: You are ready for exposure.
Figure18: You are ready for exposure.

Conclusions

I am using this registration system for my gum prints for more than 8 months and so far, I found it very useful in achieving good registration and prints that do not show registration artifacts. I hope that this article may contribute in helping others printers.

Andrea Baldi is an Italian amateur photographer with passion for black and white photography and alternative processes. Andrea is working with cyanotype, vandyke, ziatype and gum printing. (See @baldi_andrea_cirop on Instagram)
For any question just comment below or email Andrea: [email protected].

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